Search

The neuroendocrine system of crustaceans is complex and regulates many processes, such as development, growth, reproduction, osmoregulation, behavior, and metabolism. Once stimulated, crustaceans' neuroendocrine tissues modulate the release of monoamines, ecdysteroids, and neuropeptides that can act as hormones or neurotransmitters. Over a few decades, research has unraveled some mechanisms governing these processes, substantially contributing to understanding crustacean physiology. More aspects of crustacean neuroendocrinology are being comprehended with molecular biology, transcriptome, and genomics analyses. Hence, these studies will also significantly enhance the ability to cultivate decapods, such as crabs and shrimps, used as human food sources. In this review, current knowledge on crustacean endocrinology is updated with new findings about crustacean hormones, focusing mainly on the main neuroendocrine organs and their hormones and the effects of these molecules regulating metabolism, growth, reproduction, and color adaptation. New evidence about vertebrate-type hormones found in crustaceans is included and discussed. Finally, this review may assist in understanding how the emerging chemicals of environmental concern can potentially impair and disrupt crustacean's endocrine functions and their physiology. [Display omitted] [ABSTRACT FROM AUTHOR]

The cladoceran crustacean Daphnia has long been a model of energy allocation studies due to its important position in the trophic cascade of freshwater ecosystems. However, the loci for controlling energy allocation between life history traits still remain unknown. Here, we report CRISPR/Cas-mediated target mutagenesis of DNA methyltransferase 3.1 (DNMT3.1) that is upregulated in response to caloric restriction in Daphnia magna. The resulting biallelic mutant is viable and did not show any change in growth rate, reproduction, and longevity under nutrient rich conditions. In contrast, under starved conditions, the growth rate of this DNMT3.1 mutant was increased but its reproduction was reciprocally reduced compared to the wild type when the growth and reproduction activities competed during a period from instar 4 to 8. The life span of this mutant was significantly shorter than that of the wild type. We also compared transcriptomes between DNMT3.1 mutant and wild type under nutrient-rich and starved conditions. Consistent with the DNMT3.1 mutant phenotypes, the starved condition led to changes in the transcriptomes of the mutant including differential expression of vitellogenin genes. In addition, we found upregulation of the I am not dead yet (INDY) ortholog, which has been known to shorten the life span in Drosophila, explaining the shorter life span of the DNMT3.1 mutant. These results establish DNMT3.1 as a key regulator for life span and energy allocation between growth and reproduction during caloric restriction. Our findings reveal how energy allocation is implemented by selective expression of a DNMT3 ortholog that is widely distributed among animals. We also infer a previously unidentified adaptation of Daphnia that invests more energy for reproduction than growth under starved conditions. [ABSTRACT FROM AUTHOR]

This work shows an update of the sightings and reports of tiger shrimp Penaeus monodon on the Mexican coast of the Gulf of Mexico recorded from 2012 to 2019 and reports the smallest specimen found in the western Atlantic. The results show an increase of almost 300% in sightings and reports since the first report. The zone with most sightings and reports was the coast of Campeche and Yucatán. The wide range of size and distribution of the captured specimens, including the smallest specimen found in the western Atlantic and the presence of females at an advanced stage of gonadal maturity, indicates that P. monodon has established itself in the area. The possible negative effects of such establishment make necessary the proposal of measures based on scientific evidence. [ABSTRACT FROM AUTHOR]

Vitellogenesis in crustaceans is an energy-consuming process. Though the underlying mechanisms of ovarian maturation in decapod Crustacea are still unclear, evidence indicates the process to be regulated by antagonistically-acting inhibitory and stimulating factors specifically originating from X-organ/sinus gland (XO/SG) complex. Among the reported neuromediators, neuropeptides belonging to the crustacean hyperglycemic hormone (CHH)-family have been studied extensively. The structure and dynamics of inhibitory action of vitellogenesis-inhibiting hormone (VIH) on vitellogenesis have been demonstrated in several species. Similarly, the stimulatory effects of other neuropeptides of the CHH-family on crustacean vitellogenesis have also been validated. Advancement in transcriptomic sequencing and comparative genome analysis has led to the discovery of a large number of neuromediators, peptides, and putative peptide receptors having pleiotropic and novel functions in decapod reproduction. Furthermore, differing research strategies have indicated that neurotransmitters and steroid hormones play an integrative role by stimulating neuropeptide secretion, thus demonstrating the complex intertwining of regulatory factors in reproduction. However, the molecular mechanisms by which the combinatorial effect of eyestalk hormones, neuromediators and other factors coordinate to regulate ovarian maturation remain elusive. These multifunctional substances are speculated to control ovarian maturation possibly via the autocrine/paracrine pathway by acting directly on the gonads or by indirectly exerting their stimulatory effects by triggering the release of a putative gonad stimulating factor from the thoracic ganglion. Acting through receptors, they possibly affect levels of cyclic nucleotides (cAMP and cGMP) and Ca2+ in target tissues leading to the regulation of vitellogenesis. The "stimulatory paradox" effect of eyestalk ablation on ovarian maturation continues to be exploited in commercial aquaculture operations, and is outweighed by the detrimental physiological effects of this procedure. In this regard, the development of efficient alternatives to eyestalk ablation based on scientific knowledge is a necessity. In this article, we focus principally on the signaling pathways of positive neuromediators and other factors regulating crustacean reproduction, providing an overview of their proposed receptor-mediated stimulatory mechanisms, intracellular signaling, and probable interaction with other hormonal signals. Finally, we provide insight into future research directions on crustacean reproduction as well as potential applications of such research to aquaculture technology development. [ABSTRACT FROM AUTHOR]

Crustacean reproduction has been hypothesized to be under complex endocrinological regulation by peptide hormones. To further improve our understanding of the mechanisms underlying this complex regulation, knowledge is needed regarding the hormones not only of the central nervous system (CNS) such as the X-organ/sinus gland (XOSG), brain, and thoracic ganglia, but also the peripheral gonadal tissues. For example, in vertebrates, some gonadal peptide hormones including activin, inhibin, follistatin, and relaxin are known to be involved in the reproductive physiology. Therefore, it is highly likely that some peptide factors from the ovary are serving as the signals among peripheral tissues and central nervous tissues in crustaceans. In this work, we sought to find gonadal peptide hormones and peptide hormone receptors by analyzing the transcriptome of the ovary of the kuruma prawn Marsupenaeus japonicus. The generated ovarian transcriptome data led to the identification of five possible peptide hormones, including bursicon-α and -β, the crustacean hyperglycemic hormone (CHH)-like peptide, insulin-like peptide (ILP), and neuroparsin-like peptide (NPLP). Dominant gene expressions for the bursicons were observed in the thoracic ganglia and the ovary, in the CNS for the CHH-like peptide, in the heart for NPLP, and in the ovary for ILP. Since the gene expressions of CHH-like peptide and NPLP were affected by a CHH (Penaeus japonicus sinus gland peptide-I) from XOSG, we produced recombinant peptides for CHH-like peptide and NPLP using Escherichia coli expression system to examine their possible peripheral regulation. As a result, we found that the recombinant NPLP increased vitellogenin gene expression in incubated ovarian tissue fragments. Moreover, contigs encoding putative receptors for insulin-like androgenic gland factor, insulin, neuroparsin, and neuropeptide Y/F, as well as several contigs encoding orphan G-protein coupled receptors and receptor-type guanylyl cyclases were also identified in the ovarian transcriptome. These results suggest that reproductive physiology in crustaceans is regulated by various gonadal peptide hormones, akin to vertebrates. [ABSTRACT FROM AUTHOR]

PIWI-interacting RNAs (piRNAs) are abundantly found in germ cells and involved in gametogenesis and gonadal development. Information on the regulatory roles of piRNAs in crustacean reproduction, however, is scarce. Thus, we identified gonadal piRNAs of mud crab Scylla paramamosain. Of the 115,491 novel piRNAs, 596 were differentially expressed. Subsequently, 389,887 potential piRNA-target genes were predicted. The expression of 4 piRNAs and 9 genes with high piRNA interactions were validated with the inclusion of additional immature specimens, including LRP2 that is involved in growth and reproduction, MDN1 in ribosome biogenesis pathway and gametogenesis, and PRKDC , a DNA repair gene involved in gonadal differentiation and maturation. KEGG analysis further revealed the involvement of predicted piRNA target genes in gametogenesis- and reproduction-related pathways. Our findings provide baseline information of mud crab piRNAs and their differential expression between testes and ovaries suggests that piRNAs play an essential role in regulating gametogenesis and gonadal development. • 596 out of 115,491 novel piRNAs were gonadal differentially expressed. • Predicted potential target genes of piRNAs were involved in gametogenesis- and reproduction-related pathways. • piRNAs potentially regulate gametogenesis and gonadal development in crustaceans. [ABSTRACT FROM AUTHOR]

Wilder, M.N., 2019. Advances in the science of crustacean reproductive physiology and potential applications to new seed production technology. In: Jithendran, K.P.; Saraswathy, R.; Balasubramanian, C.P.; Kumaraguru Vasagam, K.P.; Jayasankar, V.; Raghavan, R.; Alavandi, S.V., and Vijayan, K.K. (eds.), BRAQCON 2019: World Brackishwater Aquaculture Conference. Journal of Coastal Research, Special Issue No. 86, pp. 6–10. Coconut Creek (Florida), ISSN 0749-0208. The shrimp culture industry continues to show expansion world-wide, and a large number of crustacean species having commercial importance are found within the order Decapoda. At present, eyestalk ablation is frequently used in hatcheries for marine shrimp in order to induce maturation under captivity, but the method is considered undesirable from the viewpoint of animal welfare. In this regard, this review details the current status of knowledge regarding crustacean reproductive mechanisms, especially in relation to research covering vitellogenin structure, structure and function of vitellogenesis-inhibiting hormone (VIH), identity of putative factors stimulating vitellogenesis, and applications of such research to developing new seed production technology. Regarding vitellogenin, full structure is now known for nearly 20 decapod species, not only for prawns/shrimps, but also for certain crab and crayfish species; vitellogenin molecules in these species have a primary structure consisting of more than 2,500 amino acid residues. VIH is a member of the crustacean hyperglycemic hormone (CHH)-family. Mature CHH-family peptides are typically comprised of 72-78 amino acids having six conserved cysteine residues. The complete identity of vitellogenesis-stimulating hormone (VSH) remains elusive, but eyestalk hormones such as red pigment-concentrating hormone (RPCH) may play a role in promoting ovarian maturation in certain species. The challenge for the future is to seek a viable alternative to eyestalk ablation based on hormonal manipulation and application of the above knowledge. [ABSTRACT FROM AUTHOR]

Triacylglycerides (TAG) are a pivotal nutrient for crustacean reproduction, rapidly accumulating in gonads and hepatopancreas during the ovary development. Glycerol‐3‐phosphate acyltransferase (GPAT) is the enzyme catalyzing the first step in TAG synthesis. In the present study, two EsGPATs subtypes (EsGPAT1 and EsGPAT2) were identified and characterized. The transcript of EsGPAT1 was highly expressed in thoracic ganglia, hepatopancreas and ovary, while EsGPAT2 was mainly detected in nervous tissues and intestine. During the ovary development, in hepatopancreas, the expression levels of EsGPAT1 increased from Stage I to its maximum at Stage IV and then declined sharply. The transcription levels of EsGPAT2 were highest at Stage I and then gradually declined to reach its minimum at Stage IV. In ovaries, the EsGPAT1 expression levels increased from Stage I to reach its maximum at Stage IV and then declined. The transcription levels of EsGPAT2 reached the peak at Stage I and then declined to the minimum at Stage III. In situ hybridization revealed they were both located in the F cells and R cells of hepatopancreas and all types of cells at Stage I, the follicle cells and the exogenous vitellogenic oocytes at Stage III and nearly mature oocytes at Stage IV of the ovary. In addition, the knockdown of EsGPAT1 downregulated the expression levels of downstream genes in TAG synthesis pathway, but it was not observed in RNAi treatment group of EsGPAT2. These results indicate that the two EsGPATs identified have different roles in TAG metabolism during the ovarian development of E. sinensis. Research highlights: 1.Two EsGPATs subtypes (EsGPAT1 and EsGPAT2) belonging to the Pfam01553 family were identified and characterized from Eriocheir sinensis, they had different tissue distribution. 2.EsGPAT1 and EsGPAT2 have the same localization in the hepatopancreas and ovaries and diametrically opposed expression patterns during ovarian development. 3.Knockdown of EsGPAT1 could downregulate the expression levels of most downstream genes in TAG synthesis pathway, while it was not observed in EsGPAT2 knockdown group. [ABSTRACT FROM AUTHOR]

Juvenile hormone analogue (JHA) insecticides are endocrine disrupters that interfere with hormonal action in insects by mimicking their juvenile hormones (JH). As the structure and functions of methyl farnesoate in crustaceans are similar to those of JH in insects, exogenous JHA insecticides could have adverse effects on the development and reproduction of crustaceans. This study examined the toxic effects of two JHA insecticides, fenoxycarb and methoprene, on a freshwater shrimp model of cherry shrimp, Neocaridina davidi. Both insecticides had detrimental effects on cherry shrimp, but fenoxycarb was more toxic than methoprene. Chronic exposure to these insecticides reduced the shrimp's body length and molting frequency. Based on transcriptome annotations for N. davidi , we identified important gene homologues that were active in both insect JH biosynthetic and degradative pathways as well as JH and ecdysteroid signaling pathways. Chronic treatments with JHAs had significant effects on these genes in N. davidi. Our transcriptomic analysis showed that genes involved in the pathways related to cuticle development, serine protease activity, and carbohydrate, peptide and lipid metabolic processes were differentially expressed in shrimp exposed to JHAs. These results demonstrate the toxicity of fenoxycarb and methoprene to freshwater crustaceans and indicate the need to monitor the use of JHA insecticides. Image 1 • Phenotypic and transcriptomic analyses were used to study the effects of JHAs on cherry shrimp. • Environmental levels of JHAs reduced body length and molting frequency. • Gene expression in juvenile hormone and ecdysteroids pathways was dysregulated by JHAs. • JHAs disturb cuticle development and carbohydrate, peptide, and lipid metabolism. Capsule: Through phenotypic observation and transcriptomic analysis on the effects of juvenile hormone analogue (JHA) insecticides on Neocaridina davidi , JHAs are found to disturb hormonal actions, as well as carbohydrate, peptide, and lipid metabolism, which then inhibit the development of N. davidi. Our results indicate the need to monitor the use of these insecticides. [ABSTRACT FROM AUTHOR]

Bisphenol A (BPA) is a representative endocrine disrupting chemical (EDC) that has estrogenic effects in aquatic animals. In recent years, due to the continuing usage of BPA, its analogues have been developed as alternative substances to replace its use. The molting process is a pivotal point in the development and reproduction of crustaceans. However, studies of the effects of EDCs on molting in crustaceans at the molecular level are scarce. In the present study, we examined the acute toxicity of BPA and its analogues bisphenol F (BPF) and S (BPS) to the brackish water flea Diaphanosoma celebensis. We further identified four ecdysteroid pathway - related genes (cyp314a1 , EcRA , EcRB , and USP) in D. celebensis , and investigated the transcriptional modulation of these genes during molting and after exposure to BPA and its analogues for 48 h. Sequencing and phylogenetic analyses revealed that these four genes are highly conserved among arthropods and may be involved in development and reproduction in the adult stage. The mRNA expression patterns of cyp314a1 , EcRA and USP were matched with the molting cycle, suggesting that these genes play a role in the molting process in the adult stage in cladocerans. Following relative real-time polymerase chain reaction (RT-PCR) analyses, BPA and its analogues were found to modulate the expression of each of these four genes differently, indicating that these compounds can disrupt the normal endocrine system function of D. celebensis. This study improves our understanding of the molecular mode of action of BPA and its analogues in D. celebensis. • Ecdysteroid pathway – related genes (cyp314a1 , EcRA , EcRB , and USP) were identified in the brackish water flea Diaphanosoma celebensis. • These genes could play a role in the molting process in the adult stage in this species. • BP analogues modulated the mRNA expression of these four genes with different mode. • Our findings indicate BP analogues can disrupt the normal endocrine system function of D. celebensis. [ABSTRACT FROM AUTHOR]

The effects of CO 2 -related acidification on two crustacean populations, the isopod Cyathura carinata and the amphipod Elasmopus rapax , were studied. Three pH levels were tested: artificial seawater without CO 2 injection and two levels of reduced pH. Even though RNA:DNA ratio was reduced for both species, no statistical significant differences were found between the control and the treatments. Both species experienced a reduction in survivorship, longevity and the body length of surviving animals; although the impairment observed in E. rapax was more severe than in C. carinata. The long life span isopod and the short life span amphipod experienced a high degree of impairment in the reproduction, likely due to the reallocation of resources from reproduction to body maintenance and increasing survival by postponing the brood production. Regardless of the underlying processes and the energetic pathways, both experienced failure to reproduce, which could lead to the local extinction of these species. • Both species show reduction in their fitness when exposed to CO 2 acidification scenarios. • The isopod Cyathura carinata survives at pH as low as 6.5, not the amphipod Elasmopus rapax • The impairment observed in E. rapax was more severe than in C. carinata. • Regardless the lengths of the lifespan, both species were unable to produce offspring. [ABSTRACT FROM AUTHOR]

The article offers a report on the first registered occurrence of a heteromorphic antennule in freshwater prawn, Macrobrachium acanthurus, during an experiment under laboratory conditions to evaluate the reproductive success of this species based on female fertility. Topics discussed include role of nervous system in heteromorphosis; physiological study of Macrobrachium acanthurus; and views on mortality of freshwater prawn.

The article discusses a study which examines the association between the size and the reproductive parameters of narrow-clawed crayfish, Pontastacus leptodactylus (P. leptodactylus). It states that the crayfish were captured from Keban Dam Lake in Turkey and anaesthetized before dissection. It mentions that the size of a male fish affects the spermatozoa production and reproductive parameters in P. leptodactylus.

Growth rate, survival, mean size of reproductive females and fertility were assessed in the terrestrial isopod Porcellionides pruinosus fed an artificial diet supplemented with potential sources of symbionts. The acquisition of symbionts was experimentally manipulated through feeding experiments to investigate the effect of the acquisition mechanism on isopod performances over 4 months. Five groups of isolated newborn were fed differently (basal diet or control; basal diet with leaf litter, faeces, gut; and basal diet mixed with antibiotic), weighed and counted at 0, 2 and 4 months. Growth rate differed significantly between diet groups at 2 and 4 months. No significant difference of survival was detected, but groups fed on a diet with supplements (leaf litter, faeces and gut) had a higher rate of survival. Size and fertility of reproductive females differed significantly across diet groups. Our findings showed the importance of the acquisition mode of symbionts on the life history of Oniscidea and the role of diet intake on the performance of P. pruinosus. [ABSTRACT FROM AUTHOR]

We aimed to study the fecundity and reproductive investment of Loxopagurus loxochelis under different environmental conditions. In total, 67 ovigerous females were analyzed, 20 from Macaé, 26 from Ubatuba and 21 from Cananéia. The cephalothoracic shield length, fecundity and reproductive investment (Ubatuba 10.2%, Macaé 8.9% and Cananéia 7.5%) were different among the regions (ANCOVA, p < 0.05), caused by different abiotic resources and environmental characteristics found in each sampling region. Cananéia had the smallest individuals and low availability of adequate shells to hermit crabs, a condition that may have affected the growth and reproduction of the animals. Macaé has a continuous transport of nutrients such as nitrogen and phosphorus to the surface promoted by the Cabo Frio Upwelling zone, which may be a favourable condition for plankton production and, consequently, the extended 'match/mismatch' adjustment of spawning females of L. loxochelis. We propose that the highest reproductive investment on the Ubatuba coast is a consequence of regional environmental scenarios of waters colder than the Cananéia region, i.e. females concentrate more energy to reproduce seasonally. Thus, we proved that patterns of L. loxochelis' reproduction can change on a regional scale according to the local condition of shell supply and water temperature. [ABSTRACT FROM AUTHOR]

Hermit crabs are soft-abdomen decapods. They depend upon gastropod shells for protection, with the latter influencing growth rate, mortality and reproduction. The present work aims to provide information about the biology and reproduction of Pagurus brevidactylus in a conservation area in Brazilian southeastern littoral. The material was sampled through active searching by SCUBA diving and refuge traps. We analyzed population structure, fecundity, reproductive output (RO), reproductive periodicity and shell utilization for P. brevidactylus. In total, 54 males, 18 non-ovigerous females, 34 ovigerous females and 10 juveniles were sampled. The females had a fecundity of 69.5 ± 65 eggs, which was lower than that compared to other populations from different localities. The RO ranged from 1.48% to 63.04%, with a mean of 26.75 ± 18.23%. There was a positive relationship between egg number and female size. The animals had continuous reproduction, but they reached smaller maximum sizes when compared with other populations. The shell occupation pattern was also different from other localities, the shells of Phrontis alba being the most occupied; this shell has a smaller size when compared to others that P. brevidactylus occupies in other localities. Therefore, P. alba could have had limited the growth and reproduction of P. brevidactylus. [ABSTRACT FROM AUTHOR]

The present study was conducted on the experimental animals, Macrobrachium dayanum (Henderson) (Crustacea: Decapoda) to analyze the seasonal changes in reproductive cycle of female, found at different locations in river Gomti (26°55'; 80°59' E), in and around Lucknow (U.P. India). The reproductive activities were found in cyclic manner in M.dayanum, which breeds continuously throughout the year but with two distinct peaks one major in the month of May-July and one minor in the month of January - Feburary. Five stages of Oogenesis i.e. proliferative, meiotic, previtellogenic, vitellogenic and resorbtion or atretic oocyte phase have been recorded in M. dayanum. Mature ova were noticed in two peaks i.e. major in month of July - August and September and minor in months of February and March. Histoarchitecture of hepatopancreas showed seasonal changes in accordance with the gonadal development. The reproductive cycle of M.dayanum is reported for the first time and very little work is known on the seasonal changes with respect to reproduction and its correlation with hepatopancreas. [ABSTRACT FROM AUTHOR]

Abstract In this study, the effects of both continuous and alternate exposure to 2 mg L−1 of flumequine (FLU) on survival, growth and reproduction of Daphnia magna were evaluated over four generations. Mortality was the most evident effect, with an average mortality rate of 23 ± 14% across generations. Individuals destined to succumb were identifiable well in advance through their discolouration and lack of development, and limited or zero reproductive capacity. Inhibition of reproduction in surviving mothers varied across the four generations (14.3 ± 17%) without an apparent correlation with the duration of exposure over generations. Significant reproductive inhibition was observed in the generation that followed three non-exposed generations (the fourth generation), pointing to a transgenerational toxicity of FLU. In another experiment, i n vitro exposure of 72 D. magna embryos to 2 mg L−1 FLU caused 14% mortality (versus 7% in the control). Among the 62 individuals that hatched alive, six showed birth defects and only one was able to survive the next few days. The other, apparently healthy newborns were randomly assigned to two groups and submitted to a reproduction test, either in the absence or in the presence of 2 mg L−1 FLU. A high mortality rate and/or strongly significantly inhibited reproduction were detected in both groups. As with previously run analogous tests with enrofloxacin, the multigenerational and embryonic tests showed a clear disruption to this crustacean population which would not be evidenced by the standard official acute and chronic tests. This indicates the necessity of taking a different and more comprehensive approach to the evaluation of substances having an inherent ability to interact with genetic material. Graphical abstract fx1 Highlights • Flumequine exposure leads to increasing toxicity over four D. magna generations. • Multigenerational and embryonic tests show harm undetectable by official tests. • Inhibition of reproduction persists in up to three unexposed generations. • Embryonic exposure causes teratogenic effects and affects survival and reproduction. [ABSTRACT FROM AUTHOR]

Abstract The study of the effects of contamination on sperm quality not only provides an early, specific and integrative response to the fraction of bioavailable pollutants, but also has been shown to predict the potential of this fraction to modify an organism's capacity to reproduce. In addition, fertility damage in invertebrates has been addressed as a major problem that may pose a threat to the maintenance of populations. In this context, the present study proposes a methodology based on the measurement of sperm DNA integrity to evaluate the impact of paternal damaged DNA on the reproductive success of Palaemon serratus. A preliminary methodological optimization step was carried out to assess the kinetics of response of spermatozoa as well as the sensitivity of the spermatozoa according to their location in the genital tract. Spermatozoa appeared to be sensitive to a short in vivo exposure to the direct acting agent methyl methanesulfonate (i.e. MMS; 2 days), with a persistence of damage even after a 30 days' recovery in a clean environment, suggesting a probable lack of DNA repair machinery. Moreover, our results revealed no difference in the level of DNA damage in mature spermatozoa whatever the exposure in spermatophore located in the terminal ampulla or in the proximal and distal part of the vas deferens. Finally, a significant decrease in the percentage of naturally bred prawns has been observed at the highest concentration of MMS (i.e. 100 μM). Nevertheless, no reproduction impairment (i.e. fertilization rate and early embryo development) following a paternal exposure has been shown in spite of very high levels of sperm DNA damage. In regard to the literature, this result raises questions concerning the kinetics of expression of genotoxic damage on progeny in the Palaemon model and future work will be led in this way. Highlights • Spermatozoa sensitivity of P. serratus to a short in vivo MMS exposure. • Persistence of DNA damage after stress cancellation. • No reproduction impairment following paternal exposure during embryonic development. [ABSTRACT FROM AUTHOR]

Abstract Injecting double-stranded (ds)RNA into abdominal muscle of female shrimp may provide a relatively simple means of reducing pre-existing virus infection loads and thus the propensity for infection to be transmitted vertically to seedstock used for aquaculture. However, to obtain regulatory approvals to use such RNA interference (RNAi) technology in hatcheries producing seedstock to be farmed for human consumption, there is a need to demonstrate that injected dsRNA will not transfer from broodstock or be maintained/amplified in their farmed progeny. To investigate this, at the time they were eyestalk ablated, female Black Tiger shrimp (Penaeus monodon) broodstock naturally impregnated with male spermatophores were injected with a 1:1 mix of dsRNAs synthesised to a 954 bp region of the gill-associated virus (GAV) genome and a 464 bp region of the firefly luciferase (Luc) gene. Eggs spawned 6 to 14 days later from each of 3 non-injected control females and 3 females injected at a dosage of 0.5 μg each dsRNA/g shrimp weight were reared separately and sampled at key developmental stages until they reached post-larval (PL) age. To detect residual dsRNA, cDNA synthesised to both native and heat-denatured (HD) total nucleic acid (TNA = RNA + DNA) extracted from the larval samples and pleopod, lymphoid organ and ovary tissues sampled from each female immediately after spawning was amplified using highly-sensitive TaqMan quantitative real-time (q)PCR tests targeting the dsGAV1 and dsLuc dsRNA sequences. Using HD TNA to strand-separate dsRNA and thus improve the detection sensitivity of the RT-qPCR tests, both dsRNAs were detected in all 3 tissues examined from injected females. Direct qPCR testing of the DNA component of each TNA confirmed that the detections were not due to residual template DNA in the purified dsRNA preparations. Similar RT-qPCR testing of both native and HD TNA extracted from pools of 50 embryos, nauplii, protozoea, and mysis and 32 individual PL reared separately for each female generated no unequivocal or consistent detections of dsGAV1 or dsLuc dsRNA. These findings provide confidence that purified dsRNA injected into female broodstock at the time an eyestalk is ablated and at the dosage tested was not effectively transferred to/amplified in progeny, and thus that the human health risks of using this RNAi strategy to reduce virus disease risks during shrimp grow-out will be negligible. Highlights • dsRNA antivirals administered to female broodstock in tail muscle were subsequently found throughout a broodstocks organs including ovary • dsRNA antivirals administered to broodstock were not detected in spawned progeny at any of the larval and postlarval life history stages examined • Data will inform future policy to allow dsRNA antiviral use in broodstock shrimp that produce progeny destined for human consumption. [ABSTRACT FROM AUTHOR]

Abstract To understand the influence the individual-rearing design will exert on selective breeding programs for feed efficiency trait of L. vannamei , this study assessed the extent of genotype by environment (G × E) interaction for feed efficiency of 15 full-sib families reared in individuals vs. in groups. Feed efficiency ratio (FER), average daily weight gain (ADG) and daily feed intake (DFI) were measured on individuals of the families in individual-rearing condition and on groups of individuals of the same families in group-rearing condition, respectively, with a restricted feeding regime. As the experimental design, each family was divided into three groups in both rearing conditions, and a total of 90 group records were used for G × E analysis. In this study, increased FER and ADG denoted as least squared means were observed in group-rearing condition compared to individual-rearing condition. Genetic variance was much higher than G × E and environmental variances for both FER and ADG, but G × E variance was higher than genetic and environmental variances for DFI. Genetic correlations between the two conditions were 0.786 and 0.909 for FER and ADG, respectively, which indicates a mild G × E interaction effect for FER and an insignificant G × E interaction effect for ADG. These results suggest that for family selection the decisions based on individual-rearing design might be applicable for production situation where shrimp are held in social groups and individual-rearing design is feasible in breeding programs for feed efficiency of L. vannamei. Highlights • Increased FER and ADG were observed in group-rearing condition. • The G x E variances for FER and ADG were much smaller than their genetic variances. • Genetic correlations of FER and ADG between the two conditions were 0.786 and 0.909, respectively. • The G x E interaction effect for FER between the two conditions was mild. [ABSTRACT FROM AUTHOR]

Accurate estimates of reproductive potential are a key component of any stock assessment. Multiple factors influencing the variability in batch fecundity of stone crabs Menippe spp. across the Florida fishery were quantified with a negative binomial regression model. Stone crabs were collected bimonthly from Cedar Key, Tampa Bay, Pavilion Key, and Sawyer Key from April 2013 through April 2015 for fecundity analysis. Batch fecundity (number of eggs per clutch) was estimated by using dry weights. Modeling results revealed that fecundity was strongly and positively related to carapace width and highly variable among locations, months, and years. Batch fecundity was lowest in spring and winter and highest in July and August, which agreed with the general understanding of seasonal patterns in crustacean reproductive cycles. Additionally, batch fecundity was 39% lower for crabs with no claws, indicating that claw removal by the fishery negatively affects reproductive output. Comparisons of estimates from a 1993-1995 fecundity study in Tampa Bay indicated that there was little difference in stone crab fecundity between individuals collected in 1993 and those collected in 2013. But this observed temporal pattern represents observations from only a small portion of the fished population and so may not fully reflect the temporal changes in fecundity occurring throughout the fishery. The present study quantified the spatial and temporal factors influencing variability in stone crab fecundity throughout the fished population of Florida. We hypothesize that spatial differences in food quality, food quantity, and fishing effort may be important drivers of variability in stone crab fecundity. Given the intense harvest and variability in reproductive output, further work should be dedicated to identifying critical spawning and recruitment areas, as well as assessments of their connectivity. [ABSTRACT FROM AUTHOR]

Several decapod crustaceans are invaders, but little is known about the biological characteristics that potentiate the success of these decapods in invaded ecosystems. Here, we evaluate and describe some aspects of the reproductive biology and development of Lysmata vittata, an invasive shrimp species in the Atlantic Ocean. In addition, we intend to provide important insights into the biology of invasion by comparing the reproductive traits of this shrimp with some of the predictions about aquatic invasive species. We used experimental and laboratory observations to evaluate the functionality of protandric simultaneous hermaphroditism (PSH), the macro and microscopic development of the ovarian portion of the ovotestes, the reproductive cycle, and the embryonic development of L. vittata. We confirm the functionality of PSH in L. vittata. This shrimp has a rapid reproductive cycle; the ovarian portion of the ovotestes develops (mean ± SD) 6.28 ± 1.61 days after spawning. Embryonic development also occurs over a short time, with a mean (± SD) of 8.37 ± 0.85 days. The larvae hatch without macroscopically visible yolk reserves. Our study provides evidence that the invasive shrimp L. vittata has reproductive and embryonic developmental characteristics (i.e., short generation time and high reproductive capacity) that may be favorable to the establishment of populations during invasive processes. [ABSTRACT FROM AUTHOR]

Phenotypic plasticity and polyphenism, in which phenotypes can be changed depending on environmental conditions, are common in insects. Several studies focusing on physiological, developmental, and molecular processes underlying the plastic responses have revealed that similar endocrine mechanisms using juvenile hormone (JH) are used to coordinate the flexible developmental processes. This review discusses accumulated knowledge on the caste polyphenism in social insects (especially termites), the wing and the reproductive polyphenisms in aphids, and the nutritional polyphenism and sexual dimorphism in stag beetles. For the comparison with non‐insect arthropods, extensive studies on the inducible defense (and reproductive polyphenism) in daphnids (crustacean) are also addressed. In all the cases, JH (and methyl farnesoate in daphnids) plays a central role in mediating environmental stimuli with morphogenetic processes. Since the synthetic pathways for juvenoids, i.e., the mevalonate pathway and downstream pathways to sesquiterpenoids, are conserved across pancrustacean lineages (crustaceans and hexapods including insects), the evolution of developmental regulation by juvenoids that control molting (ecdysis) and metamorphosis is suggested to have occurred in the ancestral arthropods. The discontinuous postembryonic development (i.e., molting) and the regulatory physiological factors (juvenoids) would have enabled plastic developmental systems observed in many arthropod lineages. In phenotypic plasticity and polyphenism, in which phenotypes can be changed depending on environmental conditions, similar endocrine mechanisms using juvenile hormone (JH) are used to coordinate the flexible developmental processes. This review discusses accumulated knowledge on the caste polyphenism in social insects, the wing and the reproductive polyphenisms in aphids, the nutritional polyphenism and sexual dimorphism in stag beetles, and the inducible defense (and reproductive polyphenism) in daphnids. In all the cases, JH plays a central role in mediating environmental stimuli with morphogenetic processes, to construct adaptive phenotypes to the environments. [ABSTRACT FROM AUTHOR]

Copyright of Iheringia. Série Zoologia is the property of Fundacao Zoobotanica do Rio Grande do Sul and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Iheringia. Série Zoologia is the property of Fundacao Zoobotanica do Rio Grande do Sul and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Patterns of allocation between reproduction, survival, and maintenance are what we call life history. By investigating the life-history strategy of sympatric species, we may understand how they are able to coexist, as different strategies are expected to evolve in species that occupy similar niche space. Terrestrial isopods are a group in which multiple species frequently inhabit the same area. Notably, they are usually infected by Wolbachia Hertig, 1936, a notorious manipulator of the hosts' reproductive processes. Thus, the aim of this study was to analyze the investment in reproduction in three sympatric and closely related species of terrestrial isopods: Atlantoscia floridana (Van Name, 1940), Atlantoscia inflata Campos-Filho and Araujo, 2015, and Atlantoscia petronioi Campos-Filho, Contreira and Lopes-Leitzke, 2012, only the latter being infected with Wolbachia. We showed that the presence of the bacteria seems not to affect the fitness of A. petronioi, because there was no clear difference in the reproductive output of infected and noninfected individuals. On the other hand, we observed that the three species possess alternative life-history strategies; that is, they differ in how much they invest in maintenance (body size) and reproductive effort. Such differences probably facilitate the species coexistence, reducing the competition among them. [ABSTRACT FROM AUTHOR]

The hatching rhythm and larval release patterns of the rocky shore crab Leptodius exaratus (H. Milne Edwards, 1834) in relation to the tidal cycle, the time of the day, and lunar cycle were investigated in the laboratory. A total of 263 ovigerous females were collected at six sites in Kuwait between April and July 2014. The pattern of larval release was monitored in relation to local tidal and dial cycles. Larval release was synchronized with local neap tide events with a significant correlation between hatching frequency and the predicted tidal height. This pattern changed towards the second half of the spawning season, and females released larvae during spring and neap tides. It was found that this species has a nocturnal hatching rhythm with larvae being released at early night during neap tides and at late night during spring tides (later in the season) as a correspondent to the expected ebb tide. The results of the laboratory experiments suggest that the hatching rhythm of L. exaratus is endogenous. These results contribute to further understand how intertidal species adjust the time of their reproduction to maximise larval survival. [ABSTRACT FROM AUTHOR]

Androdioecy (males and hermaphrodites) is a rare breeding system in multicellular organisms, found mostly in barnacles and branchiopod crustaceans. The most speciose and longest-lived androdioecious clade is the genus Eulimnadia Packard, 1874 (Branchiopoda, Spinicaudata), the clam shrimps, consisting of over 50 species that have maintained androdioecy for an estimated 24–180 million years. Many populations of Eulimnadia nevertheless comprise entirely "monogenic" hermaphrodites. Hypotheses proposed to explain the relative stability of androdioecy (sexual conflict, overdominance, and metapopulation model) differ in their predictions of the resistance of existing all-hermaphrodite populations to invasion of males and hermaphrodites. We tested whether all-hermaphroditic populations of Eulimnadia texana Packard, 1871 may be resistant to male invasion by adding males and "amphigenic" hermaphrodites to all-hermaphrodite, monogenic populations that have been inbred for eight generations. All-hermaphrodite populations of E. texana that have been selfing for multiple generations are easily invaded by males, both directly and indirectly. The addition of males also increased the productivity of these experimental treatments, suggesting a selective benefit to outcrossing and thus to males. These results do not align with the sexual conflict nor the overdominance models, but are consistent with the metapopulation model of the maintenance of androdioecy. [ABSTRACT FROM AUTHOR]

Abstract: Raising global temperatures are predicted to have strong consequences for ectotherms, as metabolic rates depend directly on external temperatures. To understand consequences for population fitness, a full life cycle approach is important because (a) temperature can have opposite effects on different vital rates (growth, survival, reproduction) and (b) sensitivities of population growth rate to changes in vital rates can vary in magnitude. As vital rates are concurrently influenced by other factors, adequately predicting temperature effects requires factors such as body size, population density and genetics to be taken into account. The aim of this study was to quantify the role of temperature on all vital rates of Daphnia magna individuals and their integrated effects on population dynamics. In addition, we evaluated how clonal lineages differed in their temperature response, both on the vital rate and population level. We performed a laboratory experiment, in which we followed 40 populations (five clonal lineages × eight temperatures) during 80 days. Due to our novel set‐up, we were able to quantify vital rates of individuals within those populations. We identified relations between vital rates and body size, lineage, temperature and population density and used a size‐structured integral projection model to integrate the experimental effects over all vital rates. We found negative density dependence in growth and reproduction, resulting in lineage‐specific carrying capacities. Population fitness showed a thermal optimum that differed among genotypes. It is interesting that we found that clones had different life‐history strategies, optimizing population fitness via different routes. As no lineage outperformed the others in all vital rates, we identified trade‐offs between vital rates, which had strong effects on the dynamics of the population. Moreover, simulations suggest that the genetic composition of mixed populations is temperature‐dependent. Our results underscore the importance of studying individuals within their population when predicting responses to environmental change. The observed density effects, which were as strong as temperature effects but explained considerably more variation in population growth, would have been overlooked in life table experiments. Furthermore, differential temperature responses emphasize the importance of genetic variation in the ability of ectotherm species such as Daphnia magna to respond to climate change. A plain language summary is available for this article. [ABSTRACT FROM AUTHOR]

Population biology of the intertidal crabs Pachygrapsus marmoratus Fabricius, 1787 and P. maurus (Lucas 1846) was investigated at cobble beaches with different levels of wave exposure. Surveys were taken monthly over 1.5 years at three intertidal levels. The growth rate of both species was similar, although P. marmoratus reached larger sizes. This species was more abundant on the mid-littoral zone of sheltered beaches, whereas P. maurus was more abundant on more exposed ones. The sex ratio was male biased in both species, particularly for the smaller and larger size classes. Both species showed an extended reproductive season, coinciding with the rising temperatures of spring and summer, with ovigerous females being found from June to September for P. marmoratus and from May to August for P. maurus. The present study indicates that both could develop adaptive strategies allowing them to coexist in the Azores littoral. The greater size of P. marmoratus seems to be an advantage on the competition for refuges with P. maurus, which results in its higher abundance and general dominance in the higher shore levels and in less exposed shores. However, P. maurus seems to be more fitted to live in the higher hydrodynamic habitats. [ABSTRACT FROM AUTHOR]

Coexistence among species is commonly related to niche divergence. However, congenerics usually are very similar in their microhabitat selection and food consumption. Thus, divergent life history strategies may represent the mechanism that allows sympatry in related species. Here, we describe and compare reproductive features in two sympatric mud crabs Panopeus americanus and P. occidentalis in an impacted mangrove area in Southern Brazil. As these species are ecologically similar, we hypothesize that these species diverge in their reproductive traits, which could explain their coexistence. Crabs were collected every two months from September 2004 to July 2006. Reproductive features such as number and size of ovigerous females, breeding season, fecundity, reproductive output, and embryo volume were assessed. Panopeus americanus produced embryos during the entire sampled period, while P. occidentalis produced only between September and March. Panopeus americanus produced more embryos considering the size of the species, had significantly lower embryo volume, and higher reproductive output than P. occidentalis. These data permit to classify P. americanus as an r-strategist and P. occidentalis as a Kstrategist regarding their reproductive traits. In conclusion, our results support the hypothesis that divergent reproductive features may allow coexistence of these mud crabs. [ABSTRACT FROM AUTHOR]

The external morphology of the larval steps in the development of the Anomuran crab Allopetrolisthes punctatus is described using material obtained under laboratory conditions and from field samples. All stages are presented with photos taken with a scanning electron microscope. For the first time in this species, and in a similar way as described for the whole family Porcellanidae, it was possible to identify one prezoea, two zoeal and one megalopa stages. The main difference between the zoeal stages is the translucid spine in the center of the telson of the zoea II, surrounded by five gross setae at each side. Also, we also studied first juvenile stages to know the size at which sexual pleopods appear, which in our samples it occurred at 1.97 mm of carapace length. [ABSTRACT FROM AUTHOR]

The sexual maturation and reproduction of crustaceans are very demanding processes for energy and nutrients. Females require the nutrients to deposit them into the eggs and allow the healthy development of embryos and early larvae survival. The lipids are essential nutrients related to the sexual maturation and the egg production, as they are sources of metabolic energy for the gonad development, as well structural molecules for the embryonic tissue formation. This work presents the effects of different dietary lipid levels (10, 12.5, 15, 17.5 and 20% of a mixture of krill and cod liver oil as lipid sources), on the growth, egg production, and egg quality, of freshwater prawn Macrobrachium acanthurus females fed during 60 days. The results showed that an inclusion higher than 15% of lipids, improved the egg production and the content of protein and lipids significantly. A lipid inclusion between 15 and 17.5% might be optimal for maturation and egg production of the females of M. acanthurus. [ABSTRACT FROM AUTHOR]

In the present study, Fenneropenaeus chinensis individuals were assigned into six groups, and fed with a diet supplemented with 0 (Control), 0.5% (Group K ), 1.0% (Group E0.5), 2.0% (Group E20), 3.0% (Group E30 .) or 5.0% (Group E 50) of poly-β-hydroxybutyrate (PHB) during their growth and spawning periods, to explore the effect of PHB on the reproductive performance of parents and the development of larvae. The experiment was lasted for 192 d to measure the mortality rate, relative percentage of survival(RPS), weight gain rate(WGR), specific growth rate (SGR) and cycle of gonadal development of parental shrimps, number of eggs, number of nauplii, stages of larval development and metamorphosis. The results indicated that PHB had an obvious effect on the fecundity of parental shrimps and growth performance of larva. Compared with control group, the mortality rate of broodstock in experimental groups decreased initially and increased subsequently with the increase of PHB concentration, while RPS showed an opposite pattern. The mortality rate of group E20 was the lowest among all groups, showing significant difference from that of other groups(P < 0.05) except group E (P > 0.05). WGR of all experimental groups was higher than that of the control group, among which, group E50 and group E10, had significantly higher WGR than the control (P<0.05). However, there was no significant difference in the cycle of gonadal development between the experimental groups and the control group (P > 0.05). The numbers of eggs and nauplii in the experimental groups were higher than those of the control group. And the numbers of eggs and nauplii in group E were significantly higher than those of the control (P < 0.05), bud showed no significant difference from those of other groups (P > 0.05). However, there was no significant difference in the duration of larval development and metamorphosis among all the groups. In summary, PHB is capable of improving the reproductive performance of parents and the survival and development of larva in F. chinensis, and 2.0% is the optimal concentration of PHB supplemented to the diet. [ABSTRACT FROM AUTHOR]

We studied the shrimp Exhippolysmata oplophoroides in southeastern Brazil (Macaé, 22º37″S; Ubatuba, 23º55″S; and Cananéia, 25º53″S) to test the hypotheses that (1) females should have the same reproductive output and fecundity at the regional scale, and (2) these reproductive parameters can vary among regions. Maximum carapace length (Macaé = 13.1 mm, Ubatuba = 12.8, Cananéia = 16), fecundity, and reproductive output differed among regions (Ancova, p < 0.05). Females in Cananéia exhibited the highest reproductive output/fecundity (18.6%/5230 embryos), followed by those in Macaé (16.0%/4365 embryos) and Ubatuba (12.6%/1206 embryos). We found that fecundity/reproductive output varies inversely with the length of the reproductive season, i.e. a considerable amount of energy is allocated during seasonal spawning periods in subtropical regions such as Cananéia. Previous studies have proved that E. oplophoroides is able to reproduce continuously in Ubatuba, with probably minor but continuous energy investment in reproduction occurring in this tropical region. In contrast, although Macaé is located at tropical latitude, it is under the influence of Cabo Frio upwelling that alters the water’s physical properties via cold water intrusion. This process may be a determining factor in the spawning seasonality of Macaé’s shrimp population, justifying the higher reproductive output recorded here than in Ubatuba. [ABSTRACT FROM AUTHOR]

The female reproductive system has been described for Dolops ranarum (Stuhlman, 1891) and various Argulus spp. but, there is no description of the reproductive system for Dipteropeltis spp. Calman, 1912 or Chonopeltis spp. Thiele, 1900. This paper describes the female reproductive system and egg laying behaviour of C honopeltis australis Boxshall, 1976 using histology, light microscopy, scanning electron microscopy and observations. The histological study of six specimens showed that the organ structure is similar to that of Argulus spp. and D. ranarum . The oocytes therefore develop in the gonocoel, are ovulated into the lumen of the ovary which is continuous with the functional oviduct and eventually the gonopore. Females of C. australis deposit eggs on the surrounding substrate while the fish is at rest, without leaving the host, thereby mitigating the risk of not locating a host again. [ABSTRACT FROM AUTHOR]

The Arabian red shrimp, Aristeus alcocki Ramadan, 1938, is one of the targets of commercial trawlers operating since 2000 along the Indian coasts at depths of 200-850 m. We report for the first time on the reproductive biology, insemination frequency, ovarian maturation, gonadosomatic index (GSI), size at maturity, and fecundity of A. alcocki investigated macroscopically and validated histologically using monthly trawl samples from the southwestern coast of India. Females have an open thelycum with five gonad developmental stages (I to V) and two stages (I and II) in males. A total of 4,170 specimens were examined and 68.6% of the females had been inseminated (carapace length (CL) 22.0-53.0 mm), predominantly during January to May. Females in stage I (immature) measured on average CL 25.5 ± 0.87 mm, those in stages IV and V (mature) CL 41.5 ± 0.62 mm. Immature males were smaller, mean CL 20.5 ± 0.5 mm. Size at first sexual maturity for females was estimated as CL 35.07 mm (total length (TL) 120-170 mm) and the inseminated specimens (CL50is) were mature at CL 31.45 mm using a non-linear method. The smallest mature female was CL 35 mm, whereas the size at maturity (CL50ms) of males was estimated as CL 19.6 mm (TL 75-96 mm). We also report synchronous oocyte development and continuous spawning activity with a peak during January to April. Information on the reproduction of this deep-water shrimp will help fishery managers estimate the stock sustainability and develop resource management measures. [ABSTRACT FROM AUTHOR]

Sperm count is an important quality assessment tool in farming programs and stock improvement in crustaceans. However, this procedure is still little used in caridean shrimps and standardization of appropriate techniques for the group is lacking. In this study, we propose a simple protocol adapted to determine sperm count in carideans using as model the Amazon River prawn Macrobrachium amazonicum . Males of dominant morphotypes (GC1 and GC2) of this species with amphidromous and hololimnetic life cycles were collected and carefully dissected. The ejaculatory duct was removed from the vas deferens and dissociated in a solution of distilled water (9 μl) and methylene blue (1 μl). Subsequently, 1 μl of this new solution was added to distilled water (9 μl), and then 1 μl was pipetted and quantified in a Neubauer chamber. The feasibility of this technique was also evaluated in animals preserved (5–480 days) in 70% ethanol from collections and the structural morphology of spermatozoa (spz) was examined. Despite morphometric differences observed between different types of males, the mean sperm count was similar for the species. In amphidromous animals, 60,258 spz/μl were registered for GC1 and 65,308 spz/μl for GC2, while in hololimnetic prawns, 48,950 spz/μl were registered in GC1 and 53,850 spz/μl in GC2. The variation in sperm count among animals preserved for different periods of time was small and very similar to those of fresh animals. Also, no microscopic changes in the structures of spz were observed. This technique can be applied to obtain a spermiogram in fresh as well as preserved animals, being especially important in studies with animals examined in population studies and deposited in collections or laboratories. This protocol can be used as a general model for spermiogram in caridean shrimps due to the great similarity of male reproductive systems within the group. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) in the environment continue to be a growing area of concern in terms of acute and chronic impacts on aquatic life. Whilst increasing numbers of studies are providing important insights into microparticle behaviour and impacts in the marine environment, a paucity of information exists regarding the freshwater environment. This study focusses on the uptake, retention and the impact of 2 mm polystyrene MPs in the freshwater cladoceran Daphnia magna in relation to food intake (algae Chlorella vulgaris), with MP size chosen to approximately match the cell size of the algae. Daphnia were exposed to varied concentrations of MPs and algae. When exposed to a single concentration of MPs Daphnia almost immediately ate them in large quantities. However, the presence of algae, even at low concentrations, had a significant negative impact on MP uptake that was not in proportion to relative availability. As MP concentrations increased, intake did not if algae were present, even at higher concentrations of MPs. This suggests that Daphnia are selectively avoiding eating plastics. Adult Daphnia exposed to MPs for 21 days showed mortality after seven days of exposure in all treatments compared to the control. However significant differences were all related to algal concentration rather than toMPconcentration. This suggests that where ample food is present, MPs have little effect on adults. There was also no impact on their reproduction. The neonate toxicity test confirmed previous results that mortality and reproduction was linked to availability of food rather than MP concentrations. This would make sense in light of our suggestion that Daphnia are selectively avoiding eating microplastics. [ABSTRACT FROM AUTHOR]

In crustaceans, successful reproductive processes, such as the transition from juvenile to adult, exhibit important morphological changes that can be detected by analyzing relative growth. This study describes the relative growth of body structures in Nematopalaemon schmitti and its secondary sexual characteristics, and also estimates the morphological sexual maturity of this species in a region influenced by upwelling. The carapace length (CL), second pleuron length (PlL), cheliped carpus length (CaL), cheliped propodus length (PrL) and the length of appendix masculina (AML) of the shrimp were measured. The relationships that best demonstrated the changes in allometric coefficient between demographic categories were AML vs. CL for males, and PlL vs. CL for females. The estimated CL for morphological sexual maturity in males was 8.51 mm and 9.30 in females. Our results showed the appendix masculine and the second pleuron were secondary sexual characteristics that play roles in reaching the morphological sexual maturity necessary for reproductive success and to assure the life cycle of this species. [ABSTRACT FROM AUTHOR]

We investigated how surface mating affects the characteristics of chimneys (diameter, height, and thickness) and burrows (total length, horizontal length, total depth, volume and shapes) in Uca rosea (Tweedie, 1937). In U. rosea, surface mating is the main mating mode, and females incubate eggs inside their own burrows. We investigated 73 randomly selected burrows with chimneys (36 females, and 37 males). We observed that chimney and burrow characteristics, except for burrow/chimney diameter, were greater in females than in similar-sized males. The burrows were I- and J-shaped, with a higher number of J-shaped burrows in females and a higher number of I-shaped burrows in males. J-shaped burrows were longer and deeper, had greater volumes, and had higher and thicker chimneys, than I-shaped burrows. Chimney characteristics were positively correlated with burrow characteristics. Our results indicate that U. rosea female burrows are used for breeding, and male burrows are used for temporary stays. [ABSTRACT FROM AUTHOR]

In crustaceans, successful reproductive processes, such as the transition from juvenile to adult, exhibit important morphological changes that can be detected by analyzing relative growth. This study describes the relative growth of body structures in Nematopalaemon schmitti and its secondary sexual characteristics, and also estimates the morphological sexual maturity of this species in a region influenced by upwelling. The carapace length (CL), second pleuron length (PlL), cheliped carpus length (CaL), cheliped propodus length (PrL) and the length of appendix masculina (AML) of the shrimp were measured. The relationships that best demonstrated the changes in allometric coefficient between demographic categories were AML vs. CL for males, and PlL vs. CL for females. The estimated CL for morphological sexual maturity in males was 8.51 mm and 9.30 in females. Our results showed the appendix masculine and the second pleuron were secondary sexual characteristics that play roles in reaching the morphological sexual maturity necessary for reproductive success and to assure the life cycle of this species. [ABSTRACT FROM AUTHOR]

This study, the third of a multi-part series on male sexual tubes in hermit crabs, the external morphology of the tube of the western Atlantic Catapagurus sharreri A. Milne-Edwards, 1880 is documented using scanning electron microscopy. The male of this species has an unpaired right sexual tube that is long (more than five coxal lengths), and curves externally and upwardly around the pleon, ending at about the mid-dorsal surface of the pleon. The tubes are subcylindrical, flexible, lack a cuticular ridge, and terminate in an opening surrounded by a dorsal beak-like and a ventral rounded lip. Setation on the tubes consist of short, simple, and relatively sparse setae, more numerous near the distal portion of the tube and gonopore. The tube is of cuticular origin, and represents an extension of the calcified right coxa. The morphology of the tip of the tube, with similar to the tip of an elephant trunk, is particularly intriguing and possibly represents a character shared with other species of Catapagurus A. Milne-Edwards, 1880. The tube of C. sharreri is compared with those documented for other species in previous parts of this series, the marine pagurid Micropagurus acantholepis (Stimpson, 1858), and the semi-terrestrial coenobitids Coenobita perlatus H. Milne Edwards, 1837 and C. clypeatus (Fabricius, 1787). The evolution of highly diverse sexual tubes in 63.6% of the genera of Paguridae that are know to have them, continues to raise intriguing questions for future study. [ABSTRACT FROM AUTHOR]

In this study, the copepod Tigriopus japonicus was exposed to different cadmium (Cd) treatments (0, 2.5, 5, 10, and 50 μg/L in seawater) for five generations (F0-F4), followed by a two-generation (F5-F6) recovery period in clean seawater. Six life-history traits (survival, developmental time of nauplius phase, developmental time to maturation, number of clutches, number of nauplii/clutch, and fecundity) were examined for each generation. Metal accumulation was also analyzed for generations F0-F6. Additionally, proteome profiling was performed for the control and 50 μg/L Cd-treated F4 copepods. In F0-F4 copepods, Cd accumulated in a concentration-dependent manner, prolonging the development of the nauplius phase and maturation and reducing the number of nauplii/clutch and fecundity. However, during F5-F6, Cd accumulation decreased rapidly, and significant but subtle effects on growth and reproduction were observed only for the highest metal treatment at F5. Proteomic analysis revealed that Cd treatment had several toxic effects including depressed nutrient absorption, dysfunction in cellular redox homeostasis and metabolism, and oxidative stress, resulting in growth retardation and reproduction limitation in this copepod species. Taken together, our results demonstrate the relationship between molecular toxicity responses and population-level adverse outcomes in T. japonicus under multigenerational Cd exposure. [ABSTRACT FROM AUTHOR]

The additive flame retardant triphenyl phosphate (TPHP) has been frequently detected in environments and biota. Evidences indicate that TPHP has potential risks to aquatic organisms. Seldom has been reported about its chronic effects to aquatic organism at low trophic levels, such as Cladocera. In the present study, <12 h old Daphnia magna ( D. magna ) were exposed to 0, 5, 50 or 500 μg/L TPHP for 21 days to investigate the chronic effects of TPHP on body length, fecundity and survival. Meanwhile, D. magna PCR arrays were used to evaluate the transcriptional responses of 155 genes involved in 40 pathways. Exposure to 500 μg/L TPHP for 21 days significantly decreased the body lengths of both F0 and F1 generation and inhibited the fecundity of F0 generation. Results of RT-qPCR showed that the expressions of 76 genes involved in 15 pathways were significantly altered after exposure to 500 μg/L TPHP for 21 days. The significantly altered pathways related to genetic information processing, cellular process and metabolism might be responsible for the observed effects of TPHP. Overall, our results showed that chronic exposure to TPHP caused developmental and reproductive toxicities to D. magna . [ABSTRACT FROM AUTHOR]

Copyright of Iheringia. Série Zoologia is the property of Fundacao Zoobotanica do Rio Grande do Sul and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ovarian development in crustacean is controlled by several factors, among which a neuropeptide gonad-inhibiting hormone ( GIH) is known to inhibit vitellogenin (Vg) synthesis in the ovary. It has been postulated that GIH may control Vg synthesis by inhibiting the release of gonad-stimulating factor ( GSF) from brain and thoracic ganglia. To prove this hypothesis, this study was primarily aimed to investigate the influence of GIH on the release of GSF from thoracic ganglia of Penaeus monodon. Our result showed that GIH did not suppress the release of putative GSF from thoracic ganglia by calcium ionophore A23187 as the induction of oocyte growth in the ovary explants that were cocultured with thoracic ganglia in the presence of A23187 was not affected by the addition of recombinant GIH protein. In addition and interestingly, when the ovary explants were incubated with the recombinant GIH alone, the oocyte growth was increased at the rate comparable to that induced by A23187 in the presence of thoracic ganglia. Hence, our in vitro study demonstrated that the stimulation of GSF released from thoracic ganglia is independent of GIH, and that the GIH has a dual function in oocyte growth stimulation and inhibition of Vg synthesis in the early stage of ovarian development. This expands our knowledge on the regulation of ovarian development in shrimp by GIH. Further in vivo studies in this novel aspect of GIH function will be useful for the improvement of shrimp ovarian maturation in the future. [ABSTRACT FROM AUTHOR]

Reproduction is a critical event in the life cycle of animals, and a high amount of energy is allocated to it. The aim of this study was to characterize the reproductive biology of two recently described species ofHyalellafrom the north-east region of state of Rio Grande do Sul in southern Brazil. The specimens were collected during 12 months from a stream source (Hyalella georginae) and from a water reservoir (H. gauchensis), in Palmeira das Missões municipality, state of Rio Grande do Sul. Upon sampling, ovigerous females and pairs in precopulatory behaviour were separated into microtubes. In the laboratory, the cephalothorax length (CL in mm) of all specimens was measured. Male size at onset of sexual maturity was larger than that of the females, in both species. There was a correlation between the size of paired males and females: larger males carried larger females, in bothHyalellaspecies. Precopulatory pairs were found throughout the year; however,H. georginaehad a higher frequency in spring, andH. gauchensisin autumn. There was a positive correlation between the CL of ovigerous females and the number of eggs/juveniles. A reduction in the number of eggs throughout the embryonic development was observed inH. georginae. The average fecundity ofH. georginaewas significantly higher thanH. gauchensis. The differences between the reproductive biology of these species may be related to the physical and environmental conditions at which they are exposed in their habitats. [ABSTRACT FROM AUTHOR]