93 results on '"MICRATHENA"'
Search Results
2. Single-Island Endemism despite Repeated Dispersal in Caribbean Micrathena (Araneae: Araneidae): An Updated Phylogeographic Analysis
- Author
-
Lily Shapiro, Greta J. Binford, and Ingi Agnarsson
- Subjects
phylogeny ,Caribbean biogeography ,GAARlandia ,arachnid ,araneae ,Micrathena ,Biology (General) ,QH301-705.5 - Abstract
Island biogeographers have long sought to elucidate the mechanisms behind biodiversity genesis. The Caribbean presents a unique stage on which to analyze the diversification process, due to the geologic diversity among the islands and the rich biotic diversity with high levels of island endemism. The colonization of such islands may reflect geologic heterogeneity through vicariant processes and/ or involve long-distance overwater dispersal. Here, we explore the phylogeography of the Caribbean and proximal mainland spiny orbweavers (Micrathena, Araneae), an American spider lineage that is the most diverse in the tropics and is found throughout the Caribbean. We specifically test whether the vicariant colonization via the contested GAARlandia landbridge (putatively emergent 33–35 mya), long-distance dispersal (LDD), or both processes best explain the modern Micrathena distribution. We reconstruct the phylogeny and test biogeographic hypotheses using a ‘target gene approach’ with three molecular markers (CO1, ITS-2, and 16S rRNA). Phylogenetic analyses support the monophyly of the genus but reject the monophyly of Caribbean Micrathena. Biogeographical analyses support five independent colonizations of the region via multiple overwater dispersal events, primarily from North/Central America, although the genus is South American in origin. There is no evidence for dispersal to the Greater Antilles during the timespan of GAARlandia. Our phylogeny implies greater species richness in the Caribbean than previously known, with two putative species of M. forcipata that are each single-island endemics, as well as deep divergences between the Mexican and Floridian M. sagittata. Micrathena is an unusual lineage among arachnids, having colonized the Caribbean multiple times via overwater dispersal after the submergence of GAARlandia. On the other hand, single-island endemism and undiscovered diversity are nearly universal among all but the most dispersal-prone arachnid groups in the Caribbean.
- Published
- 2022
- Full Text
- View/download PDF
3. Orb-weaving spiders show a correlated syndrome of morphology and web structure in the wild.
- Author
-
Fisher, David N, Pruitt, Jonathan N, and Yeager, Justin
- Subjects
- *
ORB weavers , *SPIDER webs , *BODY size , *MORPHOLOGY , *JUMPING spiders - Abstract
Extended phenotypes are traits that exist outside the physical body of organisms. Despite their role in the lives of the organisms that express them and other organisms influenced by extended phenotypes, the consistency and covariance with morphological and behavioural traits of extended phenotypes has rarely been evaluated. We repeatedly measured an extended phenotype involved in prey acquisition (web structure) of wild orb-weaving spiders (Micrathena vigorsii), which re-build their webs daily. We related web structure to behaviours and spider body length. Web diameter and web density were repeatable among individuals, reaction to a predation threat was very marginally so, and response to a prey stimulus and web evenness were not repeatable. Larger spiders spun wider webs, had webs with increased thread spacing, and the spider possibly tended to react more slowly to a predation threat. When a spider built a relatively larger web it was also a relatively less dense and less even web. The repeatability of web construction and relationship with spider body size we found may be common features of intra-population variation in web structure in spiders. By estimating the consistency and covariances of extended phenotypes we can begin to evaluate what maintains their variation and how they might evolve. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
4. Spiders (Araneae) Collected as Prey by the Mud-Dauber WaspsSceliphron caementariumandChalybion californicum(Hymenoptera: Sphecidae) in Southeastern Nebraska
- Author
-
Tyler B. Corey, Earl Agpawa, and Eileen A. Hebets
- Subjects
0106 biological sciences ,Sphecidae ,biology ,Sceliphron caementarium ,05 social sciences ,Zoology ,Chalybion californicum ,Hymenoptera ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Micrathena ,Predation ,Mud dauber ,Nest ,Insect Science ,0501 psychology and cognitive sciences ,050102 behavioral science & comparative psychology ,Agronomy and Crop Science ,Ecology, Evolution, Behavior and Systematics - Abstract
Predator diets represent a potential interaction between local prey availability, prey antipredator defenses, and predator foraging behavior. Female spider-specialist mud-dauber wasps (Hymenoptera: Sphecidae) collect spiders and provision them intact, but paralyzed, to their developing larvae, providing a unique means of quantifying the diversity and abundance of prey that they capture. Mud-dauber wasps are hypothesized to be a major source of selection on antipredator defenses in web-building spiders, and the spiny and thickened abdomens of female spiny orb-weaving spiders (Araneae: Araneidae) are hypothesized to function as antiwasp defenses. We inventoried spider prey from nests of the mud-dauber wasps Sceliphron caementarium (Drury) and Chalybion californicum (Saussure), and surveyed for spider fauna in areas surrounding nest collection sites, to specifically investigate if the spiny orb-weaver Micrathena gracilis (Walckenaer) was collected as prey by these wasps. We collected nests from six sites in southeastern Nebraska from two regions that we classify based on habitat—a forest corridor and agricultural land. We collected 761 intact spider prey from 87 nests and identified them to the family level. None of these spiders were M. gracilis. Micrathena gracilis were rare in faunal surveys on agricultural land and, surprisingly, absent in forest corridor surveys. Mud-dauber wasps were more common; we collected more spiders on agricultural land than in the forest corridor. We propose that in agricultural landscapes, the lack of certain spiders in mud-dauber wasp nests is driven by habitat use differences between predators and prey rather than physical antipredator defenses.
- Published
- 2021
5. Testing the hypothesized antipredator defence function of stridulation in the spiny orb-weaving spider, Micrathena gracilis
- Author
-
Tyler B. Corey and Eileen A. Hebets
- Subjects
0106 biological sciences ,Spider ,biology ,Adult female ,05 social sciences ,Zoology ,Stridulation ,Sound production ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Micrathena ,Predation ,Form and function ,0501 psychology and cognitive sciences ,Animal Science and Zoology ,050102 behavioral science & comparative psychology ,Predator ,Ecology, Evolution, Behavior and Systematics - Abstract
The observable diversity of antipredator defences across organisms demonstrates predation's impact on trait evolution. The functions of many traits that are presumed to have an antipredator function have never been directly tested. The spiny orb-weaving spider, Micrathena gracilis, for example, stridulates when grasped. While stridulation was first hypothesized to be an antipredator defence nearly 50 years ago, no data exist to support this hypothesis. To explore the form and function of M. gracilis stridulation, we first quantified the behavioural and acoustical properties of sound production. Next, using laboratory assays, we directly tested the effect of stridulation on survival with an avian predator – blue jays, Cyanocitta cristata. Finally, we conducted a large mark–recapture field study in which we compared the natural survival of experimentally manipulated adult female M. gracilis that could not stridulate (silenced) versus could stridulate (control). Stridulatory pulses produced broadband frequency spectra, consistent with acoustic antipredator defences in other taxa. We also observed stridulation by male M. gracilis for the first time. In staged laboratory interactions with captive blue jays, we found no differences in survival between silenced and control M. gracilis. Similarly, in our mark–recapture field study, we found no differences in survival estimates between silenced and control groups, nor an effect of stridulation rate. While M. gracilis stridulation closely resembles antipredator stridulation in other arthropods, our behavioural data do not yet provide solid support for an antipredator function in M. gracilis.
- Published
- 2020
6. Spiders hanging out in the rain
- Author
-
Denisse Sanchez Masis and Gilbert Barrantes
- Subjects
0106 biological sciences ,Costa Rica ,Spider ,biology ,Araneoidea ,010607 zoology ,Zoology ,biology.organism_classification ,Leucauge ,010603 evolutionary biology ,01 natural sciences ,Micrathena ,Heavy rain ,Cyrtophora citricola ,Insect Science ,Argiope argentata ,Behavioural response ,Ecology, Evolution, Behavior and Systematics ,Gasteracantha cancriformis - Abstract
Behavioural adjustments to changing environmental conditions are advantageous for spiders, as such adjustments likely allow spiders to remain in good hunting sites. Here, we describe the behavioural response of seven araneoid species to heavy rain in the neotropics. Five of the seven spiders drastically modified their position on the web, relative to the typical resting position. Four of these species (Allocyclosa bifurca, Argiope argentata, Cyrtophora citricola, and Leucauge mariana) hung from hub threads using their legs III and IV, oriented the anterior section of the prosoma downward, and moved legs I and II forward in front of the spider's eyes. Trichonephila clavipes had a similar response, but hung from only its legs IV. Two other species (Gasteracantha cancriformis and Micrathena duodecimspinosa) did not show an apparent response to heavy rain. The change in position reduces the spider's surface that heavy rain could impact, and speeds water drainage which may reduce pathogen infection. Universidad de Costa Rica/[833-C0-251]/UCR/Costa Rica UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Biología UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Biodiversidad y Ecología Tropical (CIBET)
- Published
- 2021
7. Water harvesting during orb web recycling
- Author
-
Brent D. Opell
- Subjects
0106 biological sciences ,Spider ,biology ,Leucauge venusta ,Araneus marmoreus ,010607 zoology ,Nocturnal ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Micrathena ,Rainwater harvesting ,Animal science ,Insect Science ,Relative humidity ,Argiope trifasciata - Abstract
Before constructing an orb web, an araneoid spider takes down and ingests the previous day's web. Nocturnal species do this either during the early evening or in the early morning and diurnal species during the early morning, times of the day when relative humidity (RH) is high. Under these conditions the hygroscopic glue droplets of a web's viscous prey capture thread attract atmospheric moisture, providing a net gain of water when a spider ingests its web. The contribution of web recycling to a spider's water budget has been estimated, but not determined empirically. This study does so for adult females of four species (Araneus marmoreus Clerck, 1757, Argiope trifasciata (Forskal, 1775), Leucauge venusta (Walckenaer, 1841), and Micrathena gracilis (Walckenaer, 1805)) by first determining the total volume of a web's glue droplets at 20% and 37% RH to estimate the water invested in web during construction. Subtracting each of these values from the web's total droplet volume at 90% RH approximates the range of water harvested when the web is recycled. High estimates of the net water gained range from 0.45% of a spider's body mass (3.01 µl water gained) in A. marmoreus to 0.88% of body mass (0.19 µl water gained) in L. venusta. In A. trifasciata, the water gained when a web is ingested is equivalent to 29% of a spider's daily evaporative water loss.
- Published
- 2021
8. Presence and Function of Dopamine Transporter (DAT) in Stallion Sperm: Dopamine Modulates Sperm Motility and Acrosomal Integrity.
- Author
-
Urra, Javier A., Villaroel-Espíndola, Franz, Covarrubias, Alejandra A., Rodríguez-Gil, Joan Enric, Ramírez-Reveco, Alfredo, and Concha, Ilona I.
- Subjects
- *
SPERM motility , *DOPAMINE , *CATECHOLAMINES , *HORSE reproduction , *MICRATHENA , *STALLIONS , *NEUROPHYSIOLOGY - Abstract
Dopamine is a catecholamine with multiple physiological functions, playing a key role in nervous system; however its participation in reproductive processes and sperm physiology is controversial. High dopamine concentrations have been reported in different portions of the feminine and masculine reproductive tract, although the role fulfilled by this catecholamine in reproductive physiology is as yet unknown. We have previously shown that dopamine type 2 receptor is functional in boar sperm, suggesting that dopamine acts as a physiological modulator of sperm viability, capacitation and motility. In the present study, using immunodetection methods, we revealed the presence of several proteins important for the dopamine uptake and signalling in mammalian sperm, specifically monoamine transporters as dopamine (DAT), serotonin (SERT) and norepinephrine (NET) transporters in equine sperm. We also demonstrated for the first time in equine sperm a functional dopamine transporter using 4-[4-(Dimethylamino)styryl]-N-methylpyridinium iodide (ASP+), as substrate. In addition, we also showed that dopamine (1 mM) treatment in vitro, does not affect sperm viability but decreases total and progressive sperm motility. This effect is reversed by blocking the dopamine transporter with the selective inhibitor vanoxerine (GBR12909) and non-selective inhibitors of dopamine reuptake such as nomifensine and bupropion. The effect of dopamine in sperm physiology was evaluated and we demonstrated that acrosome integrity and thyrosine phosphorylation in equine sperm is significantly reduced at high concentrations of this catecholamine. In summary, our results revealed the presence of monoamine transporter DAT, NET and SERT in equine sperm, and that the dopamine uptake by DAT can regulate sperm function, specifically acrosomal integrity and sperm motility. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
9. Rectifying the identities of the males of two Micrathena species (Araneae Araneidae), with report of the first case of intersexuality in the genus
- Author
-
Rodrigo Nunes da Fonseca, Alessandra da Silva de Alvarenga, Ivan L. F. Magalhaes, and Abel Pérez-González
- Subjects
Male ,Arthropoda ,Fauna ,Zoology ,Molecular evidence ,Micrathena ,Species group ,Arachnida ,Animals ,Animalia ,Atlantic forest ,Ecology, Evolution, Behavior and Systematics ,Taxonomy ,Spider ,biology ,Araneoidea ,Animal Structures ,Spiders ,Biodiversity ,biology.organism_classification ,Araneidae ,Araneae ,Animal Science and Zoology ,Taxonomy (biology) ,Female ,Animal Distribution - Abstract
Despite extensive taxonomic work on the Neotropical fauna of the spider genus Micrathena Sundevall, for 27 out of 117 (23%) species only the female morphology has been described, and some of the previously hypothesized male-female matches have been proven erroneous. This work provides new insight about sex matching in two species: Micrathena ruschii (Mello-Leitão, 1945) and Micrathena lata Chickering, 1960. For Micrathena ruschii, the male previously hypothesized to belong to this species was collected with females in Itatiaia; we here present morphologically different males, also collected with females, in Macaé, both in Rio de Janeiro, Brazil. Through a DNA barcoding approach, we present molecular evidence indicating conspecificity of M. ruschii females with the males collected in Macaé, proving the male from Itatiaia to be a misidentification. Therefore, a description of the correct male of Micrathena ruschii is herein provided. The male previously identified as M. ruschii probably represents an undescribed species but is not named here due to scarcity of material. We also describe for the first time the male of Micrathena lata based on one specimen collected in Misiones, Argentina. This male specimen belongs to the militaris species group, where M. lata is the only species from the Atlantic Forest previously only known by females. In addition, we detect an intersexual specimen of Micrathena ruschii, revealing the first case of intersexuality for the genus.
- Published
- 2020
10. Single-Island Endemism despite Repeated Dispersal in Caribbean Micrathena (Araneae: Araneidae): An Updated Phylogeographic Analysis.
- Author
-
Shapiro, Lily, Binford, Greta J., and Agnarsson, Ingi
- Subjects
- *
COLONIZATION (Ecology) , *ORB weavers , *BIODIVERSITY , *ENDEMIC animals , *SPECIES diversity , *ISLANDS - Abstract
Island biogeographers have long sought to elucidate the mechanisms behind biodiversity genesis. The Caribbean presents a unique stage on which to analyze the diversification process, due to the geologic diversity among the islands and the rich biotic diversity with high levels of island endemism. The colonization of such islands may reflect geologic heterogeneity through vicariant processes and/ or involve long-distance overwater dispersal. Here, we explore the phylogeography of the Caribbean and proximal mainland spiny orbweavers (Micrathena, Araneae), an American spider lineage that is the most diverse in the tropics and is found throughout the Caribbean. We specifically test whether the vicariant colonization via the contested GAARlandia landbridge (putatively emergent 33–35 mya), long-distance dispersal (LDD), or both processes best explain the modern Micrathena distribution. We reconstruct the phylogeny and test biogeographic hypotheses using a 'target gene approach' with three molecular markers (CO1, ITS-2, and 16S rRNA). Phylogenetic analyses support the monophyly of the genus but reject the monophyly of Caribbean Micrathena. Biogeographical analyses support five independent colonizations of the region via multiple overwater dispersal events, primarily from North/Central America, although the genus is South American in origin. There is no evidence for dispersal to the Greater Antilles during the timespan of GAARlandia. Our phylogeny implies greater species richness in the Caribbean than previously known, with two putative species of M. forcipata that are each single-island endemics, as well as deep divergences between the Mexican and Floridian M. sagittata. Micrathena is an unusual lineage among arachnids, having colonized the Caribbean multiple times via overwater dispersal after the submergence of GAARlandia. On the other hand, single-island endemism and undiscovered diversity are nearly universal among all but the most dispersal-prone arachnid groups in the Caribbean. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
11. Spermatozoa ultrastructure of the pink shrimp Farfantepenaeus paulensis (Decapoda: Dendrobranchiata).
- Author
-
Braga, André L., Nakayama, Cintia L., Suita de Castro, Luis A., and Wasielesky, Wilson
- Subjects
- *
SPERMATOZOA physiology , *ELECTRON microscopy , *CYTOPLASMIC inheritance , *ANIMAL morphology , *FRESHWATER animals , *MICRATHENA - Abstract
Braga, A.L., Nakayama, C.L., Suita de Castro, L.A. and Wasielesky, W. 2011. Spermatozoa ultrastructure of the pink shrimp Farfantepenaeus paulensis (Decapoda: Dendrobranchiata). - Acta Zoologica (Stockholm) 00: 1-6. The spermatozoa ultrastructure of the pink shrimp Farfantepenaeus paulensis was investigated in this morphological study. Spermatophores and spermatozoa were analyzed by electron microscopy. The pink shrimp spermatophore is divided into two regions: the appendage and the spermatophore main body, where spermatozoa are grouped in a spermatic mass. Pink shrimp spermatozoa are unistellate and are composed of main body and single spike. The spermatozoa body comprises a perinuclear cytoplasmic band, nucleus, acrosomal cap, and subacrosomal region. The spermatozoa cell mean total length was 10.71 μm, the mean body diameter was 5.56 μm, and the mean spike length and diameter were 5.15 μm and 0.85 μm, respectively. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
12. Phylogenetic analysis of Micrathena and Chaetacis spiders (Araneae: Araneidae) reveals multiple origins of extreme sexual size dimorphism and long abdominal spines.
- Author
-
Magalhães, Ivan L. F. and Santos, Adalberto J.
- Subjects
- *
PHYLOGENY , *MICRATHENA , *DIMORPHISM in animals , *SPIDERS , *ORB weavers , *SEXUAL behavior in insects , *INSECT morphology , *INSECTS - Abstract
The phylogenetic relationships amongst the New World spiny orb-weaving spiders Micrathena and Chaetacis were assessed through parsimony and Bayesian analyses of morphological characters. A total of 146 characters was scored for ten outgroup taxa and 37 Micrathena and four Chaetacis species. The results indicate that Chaetacis nests within Micrathena and we propose Chaetacis as a junior synonym of Micrathena. Twelve subgeneric species groups of Micrathena are recognized and diagnosed. Species with extremely long spines evolved at least eight times in the genus and we suggest that this may be related to antipredator defences. Micrathena is primitively sexually monomorphic and extreme sexual size dimorphism has arisen at least six times in the genus. Most of these events are because of enlargement of the female in relation to the ancestral size, although in two cases sexual dimorphism was attained through male reduction, adding more data to the 'giant females' vs. 'dwarf males' controversy. The genus is probably of South American origin and has repeatedly invaded Central and North America. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
13. Spermatozoon ultrastructure of Xenoturbella bocki (Westblad 1949).
- Author
-
Obst, Matthias, Nakano, Hiroaki, Bourlat, Sarah J., Thorndyke, Mike C., Telford, Maximilian J., Nyengaard, Jens R., and Funch, Peter
- Subjects
- *
SPERMATOZOA , *ULTRASTRUCTURE (Biology) , *ELECTRON microscopy , *MITOCHONDRIA , *MICRATHENA - Abstract
Obst, M., Nakano, H., Bourlat, S.J., Thorndyke, M.C., Telford, M.J., Nyengaard, J.R. and Funch, P. 2011. Spermatozoon ultrastructure of Xenoturbella bocki (Westblad 1949). - Acta Zoologica (Stockholm) : 109-115. Here, we report on the sperm ultrastructure of Xenoturbella bocki (Westblad 1949), which we studied for the first time in detail using light, scanning and transmission electron microscopy. The mature spermatozoa are of the bilaterian primitive type, also called aquasperm and develop as uniflagellate sperm consisting of a round head with distinct mitochondria at the base and a 9+2 flagellum of approximately 42 μm in length. The acrosomal complex consists of a small, round electron translucent acrosomal vesicle and a subacrosomal base. There is no separate midpiece, and the mitochondria surround the proximal and distal centriole in the posterior part of the head. The primitive structure of the spermatozoa suggests that these fertilize the egg by free spawning, probably the ancestral mode of fertilization in early bilaterians. When compared to the spermatozoa of other metazoans, we find that the arrangement of organelles in the Xenoturbella sperm shows similarities to a wide range of protostome and deuterostome taxa and does not seem to indicate any particular phylogenetic relationship. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
14. Interspecific aggregation around the web of the orb spider Nephila clavipes: consequences for the web architecture of Leucauge venusta.
- Author
-
Hénaut, Y. and Machkour-M'Rabet, S.
- Subjects
- *
PREDATORY insects , *PREDATION , *SPIDER behavior , *FORAGING behavior , *NEPHILIDAE , *MICRATHENA , *SPIDER webs , *METEPEIRA , *ARGYRODES , *NEPHILA , *LEUCAUGE , *BEHAVIOR - Abstract
This study describes a case of interspecific aggregation involving a spider's web and its effect on web architecture of another species of spider. On two transects of 100 m each, one with Nephila clavipes (Linnaeus 1767) webs and one without, we noted the spiders associated, or not, with N. clavipes webs, and compared the web architecture of the most commonly associated species, Leucauge venusta (Walckenaer 1842). The transect with N. clavipes contained more spiders in general than that without N. clavipes, most of which were L. venusta for both transects. The height above ground of L. venusta webs associated with N. clavipes presented a larger range of distribution, which closely mimicked that of N. clavipes webs except when the N. clavipes web was at ground level. Leucauge venusta webs were more inclined when in association with N. clavipes (49.4 ± 3.3° vs 20.4 ± 2.0°). We concluded that L. venusta clearly prefers to be associated with N. clavipes, and we discuss the possible advantages of this association. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
15. Do the Color and Pattern of Micrathena gracilis (Araneae: Araneidae) Attract Prey? Examination of the Prey Attraction Hypothesis and Crypsis.
- Author
-
Chadwick Hanna
- Subjects
- *
ARACHNIDA , *SPIDERS , *MICRATHENA , *PREDATORY animals - Abstract
Abstract  Recent studies have provided evidence that spidersâ color and pattern may attract prey items to their webs, thus increasing their foraging success. However, these studies were conducted on tropical spiders, and no studies have examined this phenomenon in temperate spiders. We examined the role of color and pattern in a North American spiny orb-weaver, Micrathena gracilis. We found that prey capture rates were similar between webs that contain spiders and webs in which spiders were removed. Additionally, we found a trend that painted spiders captured more prey than unpainted spiders. Although our results were not statistically significant, they contradict previous studies examining the role of color in prey attraction. [ABSTRACT FROM AUTHOR]
- Published
- 2008
16. Living without mitochondria: spermatozoa and spermatogenesis in two species of Urodasys (Gastrotricha, Macrodasyida) from dysoxic sediments.
- Author
-
Balsamo, Maria, Guidi, Loretta, Pierboni, Lara, Marotta, Roberto, Todaro, M. Antonio, and Ferraguti, Marco
- Subjects
- *
GASTROTRICHA , *SPERMATOZOA , *MITOCHONDRIA , *MICRATHENA , *HABITATS , *FERTILIZATION (Biology) - Abstract
The spermatozoa of two species of Macrodasyida (Gastrotricha), Urodasys anorektoxys and U. acanthostylis, show an ultrastructural organization diverging from one another and from other gastrotrichs: their main peculiarity is in the absence of mitochondria. In U. anorektoxys, the acrosome is a long, twisted column inserted into the nucleus, which is basally cylindrical, and the flagellum shows rows of peculiar, large globules parallel to the axonemal doublets. In U. acanthostylis, the acrosome is completely cork-screwed and surrounds the nucleus, and the tail shows columnar accessory fibers. At present, the absence of mitochondria in the mature sperm, and the peculiar fingerprint aspect of condensed chromatin are the only traits shared by the two species. The features of the spermatozoa of these two species of Urodasys widen the range of different models of gastrotrich spermatozoa, and place the genus in a peculiar position, from the spermatological point of view, within the Macrodasyida. The loss of mitochondria in mature spermatozoa is possibly related to either the dysoxic habitat of the two species or a peculiar fertilization mechanism. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
17. Fertility of cryopreserved sperm in three bulls with different Robertsonian translocations
- Author
-
Molteni, L., Meggiolaro, D., Macchi, A. De Giovanni, Lorenzi, L. De, Crepaldi, P., Stacchezzini, S., Cremonesi, F., and Ferrara, F.
- Subjects
- *
SPERMATOZOA , *FERTILITY , *BLASTOCYST , *MICRATHENA - Abstract
Abstract: The fertility of three bulls carrying different Robertsonian translocations (rob(1;29), rob(14;17) and rob(26;29)) was evaluated. Oocytes-cumulus complexes obtained from slaughterhouse-derived ovaries were matured and then fertilised in vitro with frozen/thawed seminal material from the above mentioned subjects, and from control bulls with normal karyotype. An assessment was first made of the concentration, vitality and acrosome integrity of the seminal material to be sure that possible differences in the results of the in vitro fertilisation experiments were not due to seminal material quality. The results of the experiments, evaluated by the percentage of cleaved embryos and blastocysts per cleaved embryo, indicated that the three bulls carrying Robertsonian translocations had similar fertilising power and semen qualitative parameters to the controls. These data suggest that neither gametogenesys impairment nor decreased spermatozoa fertilising capacity is responsible for the reduced fertility in bulls with Robertsonian translocations. What the data do confirm is that the observed in vivo hypofertility for karyologically abnormal bulls is mainly due to early embryonic mortality. [Copyright &y& Elsevier]
- Published
- 2005
- Full Text
- View/download PDF
18. Protein Kinase A Activity And Protein Phosphorylation During The Mouse Sperm Acrosomal Reaction.
- Author
-
Kuji, N., Tanaka, Y., Komatsu, S., and Yoshimura, Y.
- Subjects
- *
PROTEIN kinases , *PHOSPHORYLATION , *MICRATHENA , *PHOSPHOTRANSFERASES , *SPERMATOZOA , *CHEMICAL reactions - Abstract
Using two-dimensional gel electrophoresis, changes in protein phosphorylation caused by cyclic nucleotide-dependent protein kinases were analyzed with or without exposure to a protein kinase inhibitor, H-8, during the mouse sperm acrosomal reaction. The acrosomal reaction, induced by the treatment of sperm with dibutyryl cyclic AMP or dibutyryl cyclic GMP, was inhibited by H-8. The activities of cyclic AMP-dependent protein kinase (PKA) and cyclic GMP-dependent protein kinase induced by the sperm extract were also inhibited by H-8. When endogenous PKA in sperm was activated by the addition of cyclic AMP, a 45-kDa protein spot identified by electrophoresis indicated the occurrence of phosphorylation in vivo. Furthermore, the enhanced phosphorylation of the 45-kDa protein spot was inhibited by H-8. These results suggest that the PKA-catalyzed phosphorylation of the 45-kDa protein may be involved in the regulation of the mouse sperm acrosomal reaction. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
19. Effects of neonatal administration of 17β-estradiol, β-estradiol 3-benzoate, or bisphenol A on mouse and rat spermatogenesis
- Author
-
Toyama, Yoshiro and Yuasa, Shigeki
- Subjects
- *
MICRATHENA , *SPERMATOZOA , *GAMETES , *EMBRYOLOGY - Abstract
Bisphenol A (BPA) is a global environmental contaminant that has been implicated as a potential endocrine disruptor. In the present study, newborn rats and mice were injected subcutaneously with BPA to determine the potential developmental effects on the testis. Testes were examined by light and electron microscopy at 15 weeks of age. Other groups of newborn mice and rats were injected with 17β-estradiol (E2) or β-estradiol 3-benzoate (E2B) in a similar manner. BPA, E2, and E2B had similar effects on testes. When treated animals reached puberty and spermiogenesis began, the first sign of the effects was detected in the steps 2–3 spermatids: the acrosomal granule and nucleus were deformed. Henceforth, abnormalities in the acrosome and nucleus were observed in older spermatids and spermatozoa. Ectoplasmic specialization between the Sertoli cell and spermatids was also affected: some specializations were partially or totally deleted. When animals fully matured, the effects of the agents were not found in the testes, and the animals were found to be fertile. The results of the present study show that BPA acts as an estrogen, and causes changes which appear to revert in adults. [Copyright &y& Elsevier]
- Published
- 2004
- Full Text
- View/download PDF
20. Bull semen in vitro fertility after cryopreservation using egg yolk LDL: a comparison with Optidyl®, a commercial egg yolk extender
- Author
-
Amirat, Lamia, Tainturier, Daniel, Jeanneau, Laëtitia, Thorin, Chantal, Gérard, Olivier, Courtens, Jean Luc, and Anton, Marc
- Subjects
- *
MICRATHENA , *LIPOPROTEINS , *SEMEN - Abstract
Low-density lipoproteins (LDL) have been previously isolated and identified as the cryoprotective fraction of yolk. The effect of LDL on sperm motility after freezing–thawing has been reported, but no study has been made to assess the effect of LDL on bull semen fertility. The aim of this study was to evaluate the fertility of bull semen cryopreserved in the presence of LDL. Motility of semen cryopreserved in LDL was analyzed and compared to semen cryopreserved with Optidyl®, a commercial extender containing egg yolk. To evaluate the fertilizing ability of semen, we used in vitro fertilization test, whereas acrosome and plasma membrane integrity were also evaluated. The percentage of motile spermatozoa was two fold higher after freezing in LDL than in Optidyl® 54.4% versus 30.2% (
P<0.05 ). The cleavage rate was significantly higher after fertilization with semen frozen in LDL than with Optidyl® 63.0% versus 54.8% (P<0.05 ). No significant difference was observed on the blastocyst rate after in vitro culture. Integrity of the acrosome and the plasma membrane were maintained in both extenders. In conclusion, LDL preserve bull semen quality and fertilizing ability, allowing also better semen motility, after the freeze–thaw process. [Copyright &y& Elsevier]- Published
- 2004
- Full Text
- View/download PDF
21. Formation and dynamic alterations of horizontal microdomains in sperm membranes during progesterone-induced acrosome reaction
- Author
-
Shoeb, Mohammed, Laloraya, Malini, and Kumar, Pradeep G.
- Subjects
- *
SPERMATOZOA , *CELL membranes , *MICRATHENA , *ZONA pellucida - Abstract
Capacitated mammalian spermatozoa undergo a fusion response of their head plasma membrane and the outer acrosomal membrane leading to vesiculation classically known as acrosome reaction. Acrosome reaction occurs in response to various acrosome reaction inducers including zona pellucida proteins, calcium ionophore, dibutyryl cAMP, progesterone, etc. All the acrosome reaction inducers cause a transient of calcium influx into the sperm through voltage-dependent cation channels. Efflux of chloride, stimulation of activity of phospholipases, and phosphorylation of proteins are other known changes introduced by acrosome reaction inducers. Macromolecular organization and dynamics of sperm membranes during the progression of this vesiculation are largely unexplored. In this study, we report that progesterone induced the formation of horizontal microdomains within the exofacial surfaces of sperm membranes, which showed progressive and independent alterations in molecular dynamics. In the light of this observation, we propose that sperm membrane rafts may contain both horizontal and vertical microdomains. [Copyright &y& Elsevier]
- Published
- 2004
- Full Text
- View/download PDF
22. Phosphatidylinositol 3-kinase inhibition enhances human sperm motility and sperm– zona pellucida binding.
- Author
-
Plessis, S. S. Du, Franken, D. R., Baldi, E., and Luconi, M.
- Subjects
- *
MICRATHENA , *HEMIZONIA , *SPERM motility , *ENZYME inhibitors - Abstract
Various signalling pathways are involved in the regulation of sperm motility, capacitation, acrosome reaction and sperm– zona binding. Recent data pointed out an important role for phosphatidylinositol 3-kinase (PI3K) in human sperm motility. However, no study as of yet has been carried out to determine the effect of sperm treatment with the PI3K inhibitor LY294002 on other sperm parameters. In the present study, we investigated the role of PI3K on human sperm motility, acrosome reaction and sperm–oocyte binding by using this inhibitor. We demonstrate that in vitro incubation of washed unselected spermatozoa with LY294002 increased the percentage motility and progressive motility in asthenozoospermia patients as evaluated by computer-aided sperm analysis. The compound furthermore did not influence the acrosome reaction, whilst it (further) slightly enhanced sperm-oocyte binding. Our results therefore imply that PI3K negatively affects sperm motility and oocyte binding and might suggest a possible therapeutic role for PI3K inhibitors in the treatment regime for asthenozoospermia. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
23. Does ICSI require acrosomal disruption? An ultrastructural study.
- Author
-
Takumi Takeuchi, Liliana T. Colombero, Queenie V. Neri, Zev Rosenwaks, and Gianpiero D. Palermo
- Subjects
- *
SPERMATOZOA , *FERTILIZATION (Biology) , *REPRODUCTION , *MICRATHENA - Abstract
BACKGROUND: Aggressive immobilization of sperm prior to ICSI significantly improves fertilization rates, but the mechanism of this effect is not yet clear. This study was performed in order to assess the characteristics of mechanically immobilized human sperm by transmission electron microscope (TEM). METHODS: Sperm obtained from ejaculated semen samples from three different donors were immobilized in a standard manner for ICSI. They were then injected into the perivitelline space of mouse oocytes in order to be able to locate them by TEM. Intact motile sperm injected subzonally served as controls (n = 160). Finally, the 'carrier' oocytes were fixed and processed for TEM. RESULTS: A total of 300 sperm were mechanically immobilized and inserted into the perivitelline space of mouse oocytes. Ultrathin sections revealed consistent alterations in the acrosomal region including disruption of the plasma membrane, and disruption, vesiculation or even loss of the acrosome. Thus, all of the sperm assessed had undergone some disorganization of the head, in contrast to a majority of control sperm. CONCLUSIONS: Immobilization of sperm for ICSI by compressing and rolling the sperm tails induces a variable disruption and sometimes loss of the acrosome. This could well be a reason for the higher success rates when ICSI is performed using immobilized sperm. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
24. Characterization of the acrosome reaction-inducing substance in Xenopus (ARISX) secreted from the oviductal pars recta onto the vitelline envelope
- Author
-
Ueda, Yasushi, Kubo, Hideo, and Iwao, Yasuhiro
- Subjects
- *
XENOPUS , *SPERMATOZOA , *MICRATHENA , *MONOCLONAL antibodies , *IMMUNOFLUORESCENCE - Abstract
We previously demonstrated that Xenopus sperm undergo an acrosome reaction on the vitelline envelope (VE) in response to the materials secreted from the oviductal pars recta [Dev. Biol. 243 (2002), 55]. A monoclonal antibody against the acrosome reaction-inducing substance in Xenopus (ARISX) was obtained by immunizing mice with pars recta extract (PRE). The acrosome reaction by PRE or on the VE was effectively inhibited by the intact anti-ARISX antibody as well as its Fab fragment, indicating that the antibody recognizes the epitopes localized on the acrosome reaction-inducing substance. On Western blots, the anti-ARISX antibody recognized a molecule with an apparent molecular mass of 300 kDa in PRE and in the VE, but this molecule was not detected in the coelomic envelope. The amount of ARISX in PRE was increased by the treatment of females with pregnant mare serum gonadotropin. Periodate oxidation of PRE completely abolished the acrosome reaction-inducing activity, indicating the involvement of the carbohydrate moieties of ARISX in inducing the acrosome reaction. On immunofluorescence observation, ARISX was localized in the epithelial cells in the posterior region of the pars recta and on the VE as fibrous structures. [Copyright &y& Elsevier]
- Published
- 2003
- Full Text
- View/download PDF
25. Differential release of soluble and matrix components: evidence for intermediate states of secretion during spontaneous acrosomal exocytosis in mouse sperm☆
- Author
-
Kim, Kye-Seong and Gerton, George L.
- Subjects
- *
FERTILIZATION (Biology) , *MICRATHENA , *ORGANELLES , *EXOCYTOSIS - Abstract
Although its exact role in fertilization is unknown, the acrosome is a very important, exocytotic organelle overlying the anterior aspect of sperm from many species. Structurally and functionally, the acrosome can be considered to consist of soluble and particulate compartments. One component of the particulate acrosomal matrix is the zona pellucida-binding protein sp56. Our demonstration that this protein is within the acrosomal matrix and not on the sperm plasma membrane has led us to reexamine the events of acrosomal exocytosis and the role of the sperm acrosomal matrix in the fertilization process. To visualize the soluble compartment, we have utilized sperm from transgenic mice that carry soluble green fluorescent protein (GFP) in their acrosomes and, as a means to assess the exposure of acrosomal matrix components, we have tested the ability of these sperm to bind beads coated with antibodies to sp56. The loss of GFP from the acrosomes and the binding of the beads by the sperm undergoing capacitation serve as indicators of distinct stages of acrosomal exocytosis, allowing us to define intermediates of acrosomal exocytosis that occur during the course of sperm capacitation. These experiments demonstrate that the exposure and release of acrosomal proteins during spontaneous acrosomal exocytosis is not synchronous but is regulated during capacitation. Furthermore, acrosomal exocytosis under these conditions required calcium in the medium. On the basis of these findings, we propose an alternative model for acrosomal exocytosis that considers a role for these intermediates of exocytosis during capacitation and sperm–ZP interactions. [Copyright &y& Elsevier]
- Published
- 2003
- Full Text
- View/download PDF
26. Biochemical characterization of inner sugar chains of acrosome reaction-inducing substance in jelly coat of starfish eggs.
- Author
-
H.M.M.J. Gunaratne, T. Yamagaki, M. Matsumoto, and M. Hoshi
- Subjects
MICRATHENA ,STARFISHES ,POLYSACCHARIDES - Abstract
The inception of the acrosome reaction (AR) in the starfish Asterias amurensis is perceived to be strongly associated with sulfated polysaccharide chains derived from an extremely large proteoglycan-like molecule called AR-inducing substance (ARIS), in which one of the sugar fragments, named fragment 1 (Fr. 1), was composed of the repeating units of [→4]-β-D-Xylp-(1→3)-α-D-Galp-(1→3)-α-L-Fucp-4 (SO
3 - )-(1→3)- α-L-Fucp-4(SO3 - )-(1→4)-α-L-Fucp-(1→)n . In the current study, this sugar chain is inferred to link to the peptide part by O-glycosidic linkage through a sugar chain with different structural features from Fr. 1. This inner sugar portion of ARIS was isolated as Fr. 2 from the sonicated products of pronase digest of ARIS. Fr. 2, which retains AR-inducing activity to an admirable extent and has an apparent molecular size of 400 kDa, is composed of Gal, Xyl, Fuc, GalNAc, and GlcNAc in a molar ratio of 5:1:5:4:2 with O-sulfate substitutions at Gal-4, Gal-2, Gal-2,3 and Gal-2,4 (disulfated), Fuc-4, and GlcNAc-6. The study of Fr. 2 revealed that the major portion of the inner sugar chain of ARIS is composed of the heptasaccharide units of →3)-Galp-(1→3)-Fucp-(1→3)-Galp-(1→4)-GalNAcp-(1→4)-GlcNAcp-6(SO3 - )-(1→6)-Galp-4(SO3 - )-(1→4)-GalNAcp-(1→. This new structure of inner sugar chains of ARIS is elucidated by using electrospray ionization MS along with tandem mass analysis, sugar composition analysis, and methylation analysis of the sugar fragments obtained by acid-catalyzed resin-based partial hydrolysis of Fr. 2. Furthermore, this study corroborates that the sulfate groups are solely liable to the anionic character of ARIS, which ought to be present in the sugar chains of ARIS for its biological activity. [ABSTRACT FROM AUTHOR]- Published
- 2003
- Full Text
- View/download PDF
27. Organization and modifications of sperm acrosomal molecules during spermatogenesis and epididymal maturation.
- Author
-
Kazuya Yoshinaga and Kiyotaka Toshimori
- Subjects
MICRATHENA ,EPIDIDYMIS ,SPERMATOGENESIS ,MOLECULES - Abstract
The mammalian acrosome is a highly specialized organelle overlying the anterior part of the sperm nucleus and contains a variety of proteins, including hydrolytic enzymes and matrix molecules. Functionally, the anterior acrosome is involved in the acrosome reaction or spermzona pellucida interaction, while the equatorial segment (posterior acrosome) is involved in spermegg fusion. The acrosome is formed during spermiogenesis, during which associated molecules are transported from the Golgi apparatus and organized. Many of the molecules thus arranged gradually become compartmentalized during sperm passage through the epididymis. Some of them are further modified during the fertilization process. The findings indicate that acrosomal molecules are not only restricted to a specific region (domain) of the acrosome but also undergo ongoing relocation in a stage-specific manner during sperm maturation in the testis and epididymis. Such maturation-associated modifications are considered essential for sperm molecules to reach the correct or final site before fertilization. This review focuses on the organization and modifications of the acrosomal molecules as well as their compartmentalization within the acrosome. Microsc. Res. Tech. 61:3945, 2003. © 2003 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]
- Published
- 2003
- Full Text
- View/download PDF
28. Effect of freezing temperature, at which straws were plunged into liquid nitrogen, on the post-thaw motility and acrosomal status of ram spermatozoa
- Author
-
Bag, Sadhan, Joshi, Anil, Naqvi, S.M.K., Rawat, P.S., and Mittal, J.P.
- Subjects
- *
RAMS , *FROZEN semen , *MICRATHENA - Abstract
The present study was conducted to observe the effect of initial freezing temperature on subsequent survival and acrosomal integrity of Malpura and Bharat Merino ram spermatozoa during post-thawing incubation. Semen samples were diluted in TEST–yolk-glycerol extender, loaded in 0.25 ml straws and cooled down to −25, −75 or −125 °C freezing temperature using a programmable cell freezer. Computer assisted sperm analysis and acrosomal integrity of thawed samples were assessed after thawing and at hourly intervals during incubation at 37 °C for 4 h. The percentage of motile cells in samples frozen at −125 °C were 80.3 and 63.7 after post-thawing and -thawing incubation, compared to 75.9 and 39.7 at −25 °C or 73.9 and 51.8 at −75 °C temperatures, respectively. The spermatozoa with normal acrosome were also significantly, respectively, higher in samples frozen at −125 °C, compared to −25 and −75 °C temperatures. There were no significant breed variations on percentage of motile, percentage of rapidly motile cells, percentage of normal acrosomes, curvilinear velocity and lateral head displacement except straight line velocity and average path velocity of spermatozoa. The results indicated that −125 °C initial freezing temperature conferred the best cryopreserving ability to ram spermatozoa for post-thawing thermoresistance test compared to −25 or −75 °C freezing temperature. [Copyright &y& Elsevier]
- Published
- 2002
- Full Text
- View/download PDF
29. Assessment of acrosomal status in rat spermatozoa: studies on carbohydrate and non-carbohydrate agonists
- Author
-
Bendahmane, Malika, Zeng, Hai-Tao, and Tulsiani, Daulat R.P.
- Subjects
- *
MICRATHENA , *SPERMATOZOA - Abstract
In the mouse and several other species, including man, capacitated acrosome-intact spermatozoa interact with natural [soluble zona pellucida (ZP) and progesterone (P4)] and synthetic [neoglycoproteins (ngps) and calcium (
Ca2+ ) ionophore] agonists, prior to the initiation of aCa2+ -dependent signal transduction cascade. The net result is the fusion of the sperm plasma membrane overlying the outer acrosomal membrane at multiple sites and exocytosis of acrosomal contents [i.e., induction of the acrosome reaction (AR)]. This step is believed to be a prerequisite that enables the acrosome-reacted spermatozoon to penetrate the ZP and fertilize the egg. Although the rat is one of the most commonly used laboratory animals, very little is known about the chemical nature of agonists that induce the AR in this species. The lack of this information is primarily due to the fact that the rat sperm acrosome is a relatively thin structure. Thus, it is difficult to assess the status of the sperm acrosome in this species. In this report, we describe the use of a Coomassie brilliant blue dye staining procedure to assess the status of the rat sperm acrosome by light microscopy. The procedure is highly reproducible and has allowed us to determine the effects of carbohydrate (ngps and mouse ZP) and noncarbohydrate (P4 andCa2+ ionophore) agonists on capacitated spermatozoa. In addition, we have used a pharmacological approach to examine the functional significance of calmodulin (CaM), aCa2+ -binding protein, in induction of the AR in spermatozoa. Data presented in this report demonstrate that several ngps, solubilized mZP, P4, andCa2+ ionophores induce the AR in rat spermatozoa. Furthermore, we demonstrate that, whereas CaM antagonists blocked P4-induced AR, most of the inhibitors used had no significant effect on theCa2+ ionophore-induced (nonphysiological) AR. [Copyright &y& Elsevier]- Published
- 2002
- Full Text
- View/download PDF
30. Intracellular calcium regulation in sperm capacitation and acrosomal reaction
- Author
-
Breitbart, Haim
- Subjects
- *
ZONA pellucida , *SPERMATOZOA , *MICRATHENA , *CALCIUM - Abstract
Binding to the egg''s zona pellucida stimulates the spermatozoon to undergo acrosome reaction, a process which enables the sperm to penetrate the egg. Prior to this binding, the spermatozoa undergo in the female reproductive tract a series of biochemical transformations, collectively called capacitation. The first event in capacitation is the elevation of intracellular calcium and bicarbonate to activate adenylyl cyclase (AC) to produce cyclic-AMP, which activates protein kinase A (PKA) to phosphorylate certain proteins. During capacitation, there is also an increase in actin polymerization and in the membrane-bound phospholipase C (PLC). Sperm binding to zona-pellucida causes further activation of cAMP/PKA and protein kinase C (PKC), respectively. PKC opens a calcium channel in the plasma membrane. PKA together with inositol-trisphosphate activate calcium channels in the outer acrosomal membrane, which leads to an increase in cytosolic calcium. The depletion of calcium in the acrosome will activate a store-operated calcium entry mechanism in the plasma membrane, leading to a higher increase in cytosolic calcium, resulting in membrane fusion and acrosome reaction. [Copyright &y& Elsevier]
- Published
- 2002
- Full Text
- View/download PDF
31. Orb-weaving spiders show a correlated syndrome of morphology and web structure in the wild
- Author
-
Jonathan N. Pruitt, Justin Yeager, and David N. Fisher
- Subjects
Spider ,Evolutionary biology ,Foraging ,education ,Web structure ,Biology ,Body size ,biology.organism_classification ,Phenotype ,Organism ,Predation ,Micrathena - Abstract
Extended phenotypes are traits that exist outside the physical body of the organism. Despite their potential role in the lives of both the organisms that express them and other organisms that can be influenced by extended phenotypes, the consistency and covariance with morphological and behaviour traits of extended phenotypes is rarely evaluated, especially in wild organisms. We repeatedly measured an extended phenotype that directly influences an organism’s prey acquisition, the web structure, of wild orb-weaving spiders (Micrathena vigorsii), which re-build their webs each day. We related web structure traits to behavioural traits and body size (length). Both web diameter and web density were repeatably different among individuals, while reaction to a predation threat was slightly so, but response to a prey stimulus and web symmetry were not. There was a syndrome between morphology and web structure traits, where larger spiders spun webs that were wider, had webs with increased thread spacing, and the spider tended to react more slowly to a predation threat. When a spider built a relatively larger web it was also relatively a less dense and less symmetrical web. The repeatability of web construction and relationship with spider body size we found may be common features of intra-population variation in web structure in spiders. Individual variation along the morphology and web structure syndrome could represent variation in individual foraging strategies, or age-based correlated changes. By estimating the consistency and covariances of extended phenotypes we can begin to evaluate what maintains their variation and how they might evolve.
- Published
- 2019
- Full Text
- View/download PDF
32. Zona pellucida as physiological trigger for the induction of acrosome reaction.
- Author
-
Henkel, R., Franken, D.R., and Habenicht, U.-F.
- Subjects
- *
MICRATHENA , *SPERMATOZOA , *ZONA pellucida - Abstract
Examines the zona pellucida for the induction of acrosome reaction in Germany. Evaluation of acrosomal status from sperm samples; Dependence of acrosome reaction induced by solubilized zona proteins; Effect of incubation on the spermatozoa in zonae.
- Published
- 1998
33. Evidence for the synthesis and secretion of a CBG-like serpin by human cumulus oophorus and fallopian tubes.
- Author
-
Baltes, P., Sánchez, R., Peña, P., Turley, H., and Miska, W.
- Subjects
- *
ADRENOCORTICAL hormones , *GLOBULINS , *MICRATHENA , *FALLOPIAN tubes , *SECRETION - Abstract
Examines the corticosteroid-binding globulin (CBG)-like protein by human cumulus oophorus and fallopian tubes in Germany. Description of the acrosome reaction-inducing effect of follicular cells; Effect of induced acrosome reaction with the culture medium of human cumulus oophorus; Evidence of secretion activity of the cumulus cells.
- Published
- 1998
34. Effect of angiotensin converting enzyme (ACE) and angiotensins on human sperm functions.
- Author
-
Köhn, E.-M., Müller, C., Drescher, D., Neukamm, C., El Mulla, K.F., Henkel, R., Hägele, W., Hinsch, E., Habenicht, U.F., and Schill, W.-B.
- Subjects
- *
ANGIOTENSIN converting enzyme , *SPERMATOZOA , *MICRATHENA - Abstract
Examines the effect of angiotensin converting enzyme (ACE) and angiotensins on human sperm functions. Control of the female and male reproductive functions by the renin angiontensisn system; Effect of ACE ont he capacitation process/acromosome reaction; Negative usefulness of the ACE release for clinical marker on human sperm capacitation.
- Published
- 1998
35. Determinants of sperm release and storage in a spiny orbweaving spider.
- Author
-
Bukowski, Todd C. and Christenson, Terry E.
- Subjects
- *
MICRATHENA - Abstract
Examines sperm release and storage in the spiny orbweaver, Micrathena gracilis. Manner of release to virgin females; Requirements of a complete mating; Length of second copulation; Effect of manipulating the duration of the second copulation; Influence of sperm storage in the females; Benefit from stimulation by a second male.
- Published
- 1997
- Full Text
- View/download PDF
36. On the Ultrastructure of the Mature Spermatozoon of a Chaetognath <em>Spadella cephaloptera</em>.
- Author
-
Deurs, Bo Van
- Subjects
- *
ULTRASTRUCTURE (Biology) , *SPERMATOZOA , *SPADELLA cephaloptera , *MITOCHONDRIAL pathology , *CHAETOGNATHA , *MICRATHENA - Abstract
The mature spermatozoon of Spadella cephaloptera belongs to the filiform type. At the front end it contains a membraneous cap, which may be an acrosomal structure, and some beaded sacs. A crystal structure is found in these sacs in spermatid stages. Near this front end there is a centriolar structure. A very elongated mitochondrial derivative runs through most of the sperm. In the central half of the sperm there is a structure composed of some longitudinal sacs lying alongside the axonema. The nucleus is situated in the hind end, just in front of a free flagellum. The spermatozoon is highly unique, but to some extent it agrees with spermatozoa found among arthropodes and gastropodes. [ABSTRACT FROM AUTHOR]
- Published
- 1972
- Full Text
- View/download PDF
37. Finding hot singles: matching males to females in dimorphic spiders (Araneidae : Micrathena) using phylogenetic placement and DNA barcoding
- Author
-
Ivan L. F. Magalhaes, Adalberto J. Santos, André A. Nogueira, and Pedro H. Martins
- Subjects
0106 biological sciences ,Systematics ,biology ,Otras Ciencias Biológicas ,Cytochrome c oxidase subunit I ,010607 zoology ,Zoology ,Arachnology ,PhyloCode ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,DNA barcoding ,Micrathena ,Cladistics ,Sexual dimorphism ,Ciencias Biológicas ,Araneae ,Taxonomy (biology) ,Ecology, Evolution, Behavior and Systematics ,CIENCIAS NATURALES Y EXACTAS ,Taxonomy - Abstract
Many orb-weaving spiders exhibit remarkable sexual dimorphism, hampering the matching of males and females in taxonomic studies. This is the case for the spiny Micrathena spiders, a species-rich Neotropical genus with 27% of its species known from a single sex. In this paper we document several undescribed Micrathena specimens, and test whether they belong to some of those incompletely known species. In order to do so, we: (1) tested the phylogenetic position of males and their putative females using a previous morphological dataset; (2) calculated genetic distances among individuals based on a fragment of the mitochondrial gene cytochrome c oxidase subunit I; and (3) examined their geographical distributions. These approaches, isolated or in combination, allowed us toidentify and describe the previously unknown males ofM. embira Levi, M. reimoseri Mello-Leitão, M. exlinae Levi, M. miles Simon, M. spinulata F.O. Pickard-Cambridge, M. yanomami Magalhães & Santos and M. cornuta (Taczanowski), and the female of M. beta di Caporiacco. We found that the males previously associated with M. bicolor (Keyserling), M. cornuta and M. lata Chickering had been incorrectly matched with females. The latter actually belongs to a hitherto unnamed species, herein described as Micrathena perfida, sp. nov. New geographical data are given for these and other Micrathena species. Our study highlights the importance of using different sources of data for matching the sexes in diverse groups with strong sexual dimorphism. Fil: Fiorini de Magalhaes, Ivan Luiz. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales ; Argentina. Universidade Federal de Minas Gerais; Brasil Fil: Martins, Pedro H.. Universidade Federal de Minas Gerais. Instituto de Ciências Biológicas; Brasil Fil: Nogueira, André A.. Universidade de Sao Paulo; Brasil Fil: Santos, Adalberto J.. Universidade Federal de Minas Gerais. Instituto de Ciências Biológicas; Brasil
- Published
- 2017
38. Egg sac construction by folding dead leaves in Pozonia nigroventris and Micrathena sp. (Araneae: Araneidae).
- Subjects
- *
EGG cases (Zoology) , *ORB weavers , *OVIPARITY , *INSTINCT (Behavior) , *SPIDER behavior , *MICRATHENA , *SPIDERS - Published
- 2010
- Full Text
- View/download PDF
39. Radius construction by Micrathena duodecimspinosa (Araneae: Araneidae): a puzzle within a puzzle
- Author
-
William G. Eberhard
- Subjects
0106 biological sciences ,Spider ,Insect Science ,010607 zoology ,Functional significance ,Geometry ,Radial line ,Radius ,Biology ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Micrathena - Abstract
Araneid orb weavers systematically weaken the radii in their orbs by partially or completely removing the provisional radial lines laid during radius construction. Removal of provisional radii by Micrathena duodecimspinosa (O. Pickard-Cambridge, 1890) tended to be less complete for those radii that were attached later during the radius construction stage to the same frame line; this pattern differed from previous observations of provisional radius removal in two other araneids. Patterns of removal in M. duodecimspinosa were not in accord with a previous hypothesis that provisional radius removal functions to adjust radial tensions. In addition, M. duodecimspinosa moved in complex, jerky paths during radius construction that did not occur in previous or subsequent stages of construction. These movements resulted from the spider vibrating the entire web as she moved; their functional significance is unclear.
- Published
- 2019
40. New synonymies and a revalidation in the spider genera Eustala and Micrathena (Araneae: Araneidae)
- Author
-
Adalberto J. Santos and Herbert W. Levi
- Subjects
Spider ,biology ,Synonym ,Parawixia ,Zoology ,biology.organism_classification ,Kapogea ,Micrathena ,Linyphiidae ,taxonomy ,Genus ,lcsh:Zoology ,Animal Science and Zoology ,Taxonomy (biology) ,lcsh:QL1-991 ,Neotropical region - Abstract
In this study, 10 nominal species of Eustala Simon, 1895 are synonymized with other species of the genus, mostly based on matching males and females erroneously described as different species. Parawixia rimosa (Keyserling, 1892) is considered a senior synonym of Eustala decemtuberculata Caporiacco, 1955. Eustala isosceles Mello-Leitão, 1939 is transferred to Kapogea Levi, 1997 and considered a senior synonym of Kapogea alayoi (Archer, 1958) based on abdomen shape and coloration. Micrathena beta Caporiacco, 1947 is redescribed, illustrated and transferred from Linyphiidae back to Araneidae. This species can be easily distinguished from other members of the genus by the male palpus with an enlarged and modified paracymbium and a narrower hook as a conductor. Micrathena sanctispiritus Brignoli, 1983 is removed from the synonymy with M. lindenbergi Mello-Leitão, 1940 and considered a senior synonym of M. guanabara Levi, 1985.
- Published
- 2013
41. Cues that Spiders (Araneae: Araneidae, Tetragnathidae) Use to Build Orbs: Lapses in Attention to One Set of Cues because of Dissonance with Others?
- Author
-
Thomas Hesselberg and William G. Eberhard
- Subjects
Communication ,Spider ,biology ,business.industry ,Leucauge ,biology.organism_classification ,Micrathena ,Cognitive dissonance ,Animal Science and Zoology ,Spiral (railway) ,business ,Set (psychology) ,Psychology ,Ecology, Evolution, Behavior and Systematics ,Orb (optics) - Abstract
Even for small animals such as spiders, behavioral decisions are sometimes influenced by multiple cues. Orb webs constitute exquisitely precise records of the stimuli the spider experienced and the decisions that it made while building its web. In addition, because spiders appear to sense their webs largely by touch, direct behavioral observations can determine which stimuli they probably sense. Previous studies have shown that when an orb-weaving spider decides how far apart to space successive sticky lines during orb construction, it responds to at least five different kinds of stimuli, all of which apparently use a cue from the web, the location of the previous, inner loop of sticky spiral (IL location), as a point of reference. Here we show that two additional cues from the web, which are related to the position of the temporary spiral (TS), also influence sticky spiral spacing. A combination of direct observations of spider movements, analyses of complete and partially complete webs, and responses to experimental modifications of the web of two species in different families, Micrathena duodecimspinosa (Araneidae) and Leucauge mariana (Tetragnathidae), indicate that both the TS-IL distance itself and the short-term memory of the change in TS-IL distance compared with that on other recently encountered radii correlate with sticky spiral spacing. When the TS-IL distance was large, the spiders apparently ceased to attend to other cues. Thus, even the relatively stereotyped behavior of orb construction includes variation that stems from attention-like mental processes.
- Published
- 2012
42. Web decoration of Micrathena sexpinosa (Araneae: Araneidae): a frame-web-choice experiment with stingless bees
- Author
-
Dumas Gálvez
- Subjects
biology ,Ecology ,Insect Science ,Camouflage ,Foraging ,Argiope ,biology.organism_classification ,Web decoration ,Attraction ,Tetragonisca angustula ,Predation ,Micrathena - Abstract
The function of silk web decorations in orb weaving spiders has been debated for decades. The most accepted hypothesized functions are that web decorations 1) provide camouflage against predators, 2) are an advertisement for vertebrates to avoid web damage, or 3) increase the attraction of prey to the web. Most studies have focused on only a few genera, Argiope being the most common. In this study, I evaluated the prey attraction hypothesis of silk decorations for a species of a poorly studied genus in this topic, Micrathena sexpinosa Hahn 1822. I used a web-choice experiment in which I presented empty or web-bearing frames at the end of a tunnel to stingless bees (Tetragonisca angustula). This frame-choice experiment consisted of the following comparisons: decorated web vs. empty frame, decorated web vs. undecorated web, and undecorated web vs. empty frame. Webs with decoration intercepted significantly more bees than empty frames and undecorated webs. Therefore, the decorations of Micrathena sexpinosa might play a role in increasing foraging success.
- Published
- 2011
43. Do the Color and Pattern of Micrathena gracilis (Araneae: Araneidae) Attract Prey? Examination of the Prey Attraction Hypothesis and Crypsis
- Author
-
E. Natasha Vanderhoff, Chadwick J. Hanna, and Catherine J. Byers
- Subjects
Spider ,biology ,Animal ecology ,Ecology ,Insect Science ,Foraging ,Crypsis ,Aposematism ,biology.organism_classification ,Attraction ,Ecology, Evolution, Behavior and Systematics ,Micrathena ,Predation - Abstract
Recent studies have provided evidence that spiders’ color and pattern may attract prey items to their webs, thus increasing their foraging success. However, these studies were conducted on tropical spiders, and no studies have examined this phenomenon in temperate spiders. We examined the role of color and pattern in a North American spiny orb-weaver, Micrathena gracilis. We found that prey capture rates were similar between webs that contain spiders and webs in which spiders were removed. Additionally, we found a trend that painted spiders captured more prey than unpainted spiders. Although our results were not statistically significant, they contradict previous studies examining the role of color in prey attraction.
- Published
- 2008
44. Identifying Polymorphism among Females of the Spiny-Backed Spider Thelacantha
- Author
-
S. Goodacre, G. Kanapathy, and P. Shreeganesh
- Subjects
Spider ,biology ,Ecology ,Thelacantha ,Endangered species ,IUCN Red List ,General Medicine ,Endangered spiders ,Subspecies ,biology.organism_classification ,Gasteracantha ,Micrathena - Abstract
Polymorphism, a phenomenon which is important for speciation, can be found in wide range in species. Conspicuous colour and pattern polymorphisms are widely observed among spiders, including the spiny backed spiders (Gasteracantha spp., Micrathena spp. and Thelacantha spp.), which belong to the family Araneidae. These spiders are described as „spiny backed‟ because of the presence of prominent spines on their abdomen. Thelacantha brevispina is often mistaken as crab spider. They are a scientifically less known spider species and have been categorised as an endangered species in Sri Lanka according to the Red List of 2012. The present study aims to characterise the polymorphism among theses spiders in Northern Sri Lanka. The samples, the exuviae and dead female spiders were collected from the islands and mangroves in and around the Jaffna Peninsula. The museum specimens deposited in the zoology museum at the University of Jaffna were also used in the analysis. Two different pattern morphs were observed. Morph A has the round shaped white marking on the middle of the carapace and morph B has half-moon like white markings on the carapace. Length, width and distance between spines were measured for the statistical analysis using a venire scale (least count 0.1 mm). Morph A is relatively bigger than morph B with the average length of 11.8 mm and average width of 4.0 mm. Morph B has an average length of 6.7 mm and average width of 4.6 mm. The measured lengths and widths were significantly different (p
- Published
- 2015
45. A NEW SPECIES AND A NEW SYNONYMY IN THE SPINY ORB-WEAVER SPIDER GENUS MICRATHENA (ARANEAE, ARANEIDAE)
- Author
-
Adalberto J. Santos and Marcelo O. Gonzaga
- Subjects
Systematics ,biology ,Orb-weaver spider ,Ecology ,Genus ,Insect Science ,Zoology ,biology.organism_classification ,Cicuta ,Micrathena - Abstract
A new species, Micrathena cicuta, is described and illustrated based on females from southeastern Brazil. Plectana degeeri Walckenaer is synonymized with M. plana (C.L. Koch), based upon the original description.
- Published
- 2004
46. HowMicrathena duodecimspinosa(Araneae: Araneidae) uses the elasticity of her dragline to hide her egg sac
- Author
-
William G. Eberhard
- Subjects
biology ,Ecology ,Insect Science ,Dragline excavator ,Zoology ,Elasticity (economics) ,Plant litter ,biology.organism_classification ,Micrathena - Abstract
A female Micrathena duodecimspinosa (O. P. Cambridge, 1890) used the elasticity of her long dragline to repeatedly jerk her newly constructed egg sac up and down as she lowered it into the leaf litter below. Jerking may reduce the chances that the sac will be entangled in vegetation before it reaches the leaf litter or help insert it deeper into the litter, where it is visually camouflaged.
- Published
- 2015
47. ESTIMATING THE STICKINESS OF INDIVIDUAL ADHESIVE CAPTURE THREADS IN SPIDER ORB WEBS
- Author
-
Brent D. Opell
- Subjects
Spider ,biology ,Leucauge venusta ,Ecology ,Insect Science ,Araneus marmoreus ,Cyclosa conica ,Thread (computing) ,Adhesive ,biology.organism_classification ,Biological system ,Argiope trifasciata ,Micrathena - Abstract
Sticky threads improve an orb web's ability to retain the insects that strike it, allowing a spider more time to subdue these insects before they can escape from the web. The adhesive capture threads found in most orb webs feature small droplets of aqueous material. Inside each droplet, glycoprotein granules coalesce to impart thread stickiness. An independent contrast analysis of threads produced by the adults of five species (Leucauge venusta, Argiope trifasciata, Micrathena gracilis, Cyclosa conica, Araneus marmoreus) and ontogenetic studies of the threads of two of these species show that the volume of material in a thread's droplets is directly related to its stickiness. Models based on these analyses predict thread stickiness to within an average of 11% of the mean measured values using measurements of droplet diameter and distribution that are easily made with a compound microscope. This approach will facilitate the inclusion of thread stickiness in studies that examine the properties and performance of spider orb-webs.
- Published
- 2002
48. [Untitled]
- Author
-
Todd C. Bukowski and Terry E. Christenson
- Subjects
biology ,Courtship display ,Ecology ,media_common.quotation_subject ,Zoology ,biology.organism_classification ,Micrathena ,Courtship ,Animal ecology ,Insect Science ,Sexual selection ,Mating ,Reproduction ,Sperm competition ,Ecology, Evolution, Behavior and Systematics ,media_common - Abstract
Male Micrathena gracilis require two copulations, separated by a dismount, in order to inseminate both reproductive tracts of the female. We examined several factors that might influence a male's copulatory success. Web structure influenced male courtship and dismount tactics, but not copulatory frequency. The presence of another male reduced the likelihood of a given male copulating with both tracts, a limitation mediated by sexual responsiveness of the female. Mating status of the female did influence copulatory frequency; males were less likely to copulate a second time with nonvirgin females. In summary, males modify mating activities to reduce predation by females, to reduce intermale competition, and to avoid expending gametes when there is little chance of fertilization. Females influence males by predatory activities, mediated through web structure, and enhancing sperm competition among males.
- Published
- 2000
49. The effects of temperature on the web-building behaviour of the common house spider, Achaearanea tepidariorum
- Author
-
M. S. Anderson, D. L. Claussen, L. E. Barghusen, and A. J. Bailer
- Subjects
World Wide Web ,Spider ,biology ,Reproductive success ,Habitat ,Ecology ,Ectotherm ,Achaearanea ,Agelenopsis aperta ,biology.organism_classification ,Ecology, Evolution, Behavior and Systematics ,Predation ,Micrathena - Abstract
IntroductionBody temperature affects the physiological perfor-mance of ectothermic animals. Many studies havedemonstrated both behavioural thermoregulation andthe thermal consequences of habitat selection inectotherms (Henwood 1975; Bartlett & Gates 1967;Huey et al.1989). To understand the physiologicalconsequences of habitat selection for a given species,both natural temperature regimes and the effect oftemperature on important performance traits of theanimal must be determined (Huey 1991).Spiders are ectothermic organisms; both theirmetabolic rate and their activity levels vary with tem-perature. In web-building spiders, webs can be con-sidered records of the behaviour or activity of the ani-mal during the spinning process. The web providesthe spider with prey and transmits information aboutthe surrounding environment, such as the presence ofmates or predators. Thus, differences in web qualitydue to the ambient temperature could affect the forag-ing and reproductive success of a spider.Thermoregulation and the importance of favourablebody temperatures have been studied in spiders.Riechert & Tracy (1975) demonstrated the importanceof a favourable thermal environment to the reproduc-tive success of the desert spider Agelenopsis aperta(Gertsch). Biere & Uetz (1981) concluded that theorb-weavers, Micrathena gracilis(Walckenaer), ori-ent their webs to create exposures to the sun that resultin favourable body temperatures. Lubin et al.(Lubin,Kotzman & Ellner 1991; Lubin, Ellner & Kotzman1993) found evidence that web-site changes may berelated to thermal regime when they documented sea-sonal changes in webs and web sites of Latrodectusrevivensis(Shulov). The studies of Riechert & Tracy(1975), Biere & Uetz (1981), and Lubin et al.(1991,1993) suggest that favourable body temperatures areFunctionalEcology 199711,4–10
- Published
- 1997
50. Phylogenetic analysis of Micrathena and Chaetacis spiders (Araneae: Araneidae) reveals multiple origins of extreme sexual size dimorphism and long abdominal spines
- Author
-
Adalberto J. Santos and Ivan L. F. Magalhaes
- Subjects
Sexual dimorphism ,Species groups ,Taxon ,Phylogenetic tree ,Genus ,Araneoidea ,Zoology ,Animal Science and Zoology ,Morphology (biology) ,Biology ,biology.organism_classification ,Ecology, Evolution, Behavior and Systematics ,Micrathena - Abstract
The phylogenetic relationships amongst the New World spiny orb-weaving spiders Micrathena and Chaetacis were assessed through parsimony and Bayesian analyses of morphological characters. A total of 146 characters was scored for ten outgroup taxa and 37 Micrathena and four Chaetacis species. The results indicate that Chaetacis nests within Micrathena and we propose Chaetacis as a junior synonym of Micrathena. Twelve subgeneric species groups of Micrathena are recognized and diagnosed. Species with extremely long spines evolved at least eight times in the genus and we suggest that this may be related to antipredator defences. Micrathena is primitively sexually monomorphic and extreme sexual size dimorphism has arisen at least six times in the genus. Most of these events are because of enlargement of the female in relation to the ancestral size, although in two cases sexual dimorphism was attained through male reduction, adding more data to the ‘giant females’ vs. ‘dwarf males’ controversy. The genus is probably of South American origin and has repeatedly invaded Central and North America. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 166, 14–53.
- Published
- 2012
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.