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SummaryThe Mexican tetraAstyanax mexicanuspresents two contrasting morphs, a widely distributed surface morph and a cave-adapted morph. These cave-adapted morphs have evolved independently from two different lineages (i.e. ‘old’ and ‘new’ lineages); therefore, this model system gives a unique opportunity to explore parallel adaptive evolution in biological traits. The present study corresponds to the first morphological description of theAstyanax mexicanusmaturation process of the spermatozoa and oocytes, using thermal and hormonal stimuli to promote spermatogenesis and oogenesis, considering surface and cave morphs from both lineages. We corroborate the relevance of thermal and hormonal stimuli to promote gamete maturation. The hormone Ovaprim (GnRHa + Domperidone) is an effective promoter of ovarian development, maturation end in oocytes and spawning inAstyanax mexicanus. The sperm morphology ofAstyanax mexicanusincludes the sperm head, the midpiece, and tail or flagellum. We found differences in the spermatozoan total length between environments (F= 9.929,P= 0.05) and linages (F= 49.86,P= 0.005). The oocytes showed a spherical conformation with a mean diameter of 822.4 ± 194.1 μm for the surface populations, and 604.6 ± 38.3 µm for the cave populations. The oocyte chorion presents ridges and grooves that are arranged radially towards the micropyle. A plug in the micropyle zone was observed after fertilization, confirmed by the outer membrane of the chorion, which provides some weak adhesiveness to the substrate. We observed differences in chorion thickness between the contrasting environmental conditions. This is the first morphological characterization of the Sótanos Vázquez, Escondido and Tigre, which previous to this study were only known from speleological expeditions, with no previous biological information available.

Global climate change has made heat stress tolerance an important trait to be considered in breeding programs to improve the resistance of productive animals to unfavorable environmental conditions. The aim of this study was to know the association between single nucleotide polymorphism (SNP) markers and heat stress resistance through a genome-wide association study (GWAS). Where 95 Brown Swiss dairy cows have measured body temperatures, respiratory frequencies, and genotypes. Seven SNP were detected with a statistically significant effect (P < 0.01) on respiratory frequency under heat stress. The markers with the highest association are in the Bos taurus autosome 6 (BTA 6), e.g. the BovineHD0600010397 SNP located within the FAM13A gene, and the BovineHD0600012612 SNP located within the PI4K2B gene. The ARS-BFGL-NGS-102407 SNP that is located in BTA 4 is the SNP that presents the highest number of associations to genes. Most of the genes are involved in cellular processes that are present in the resistance of individuals to high and humid environmental temperatures. These results provide new insights into the genetics of heat stress tolerance in Brown Swiss cattle in Yucatan, Mexico.

The success of crocodile conservation programs highly depends on local people’s views, perceptions, and knowledge regarding these reptiles. The present study assessed these variables across the Nichupté lagoon through semi-structured interviews. Answers were grouped into three categories: thoughts regarding the presence of crocodiles in the area, locals’ perception on crocodiles, and local knowledge on crocodiles. Most of the 221 people interviewed showed no aversion to crocodiles, 93.2% knew about the presence of crocodiles in the lagoon, and 98.1% mentioned that it is essential to conserve these reptiles. On the other hand, 77.5% (men) and 70.5% (women) agreed that “it is fine” to share the lagoon with crocodiles. Concerning people’s perceptions about crocodiles, “Quiet”, “Indispensable” and “Interesting” were the most frequent answers. Regarding the local knowledge, we found a positive, statistically significant correlation between this variable and education, with those having high school degrees mentioning "Habitat" and those with college degrees mentioning "Reptile" more frequently. Conservation policies should be redesigned to include continuous environmental education programs that promote positive attitudes towards crocodile species. They should also include measures to guarantee the dissemination of necessary information to protect human and crocodile lives, is essential to consolidate conservation programs.

The aims of this study were to determine: (i) whether sexually inexperienced photo-stimulated males housed individually in pens display less intense sexual behaviour than sexually inexperienced photo-stimulated males housed in a group, and (ii) whether these treatments vary the sexual response in anoestrous goats. Five males were housed either individually in pens (2 × 2 m) or together in a pen (5 × 6 m) and received artificially long days (16 h/light/day/2.5 months). Males were exposed to females (n = 50/group) for 15 days. Plasma testosterone did not differ between males. Male sexual behaviour was recorded on days 0-2 after introduction to females. On days 0-2, nudging was higher in males in group than those individual. On days 0 and 2 anogenital sniffing were higher in males in group, on day 1 was similar between males. Mounting attempts were similar between groups. On day 1 mounts with intromission did not differ but on day 2 were more in males in group. On day 0 self-urination were more in males in group, but on days 1 and 2 were similar between groups. On day 0 flehmen were more in males individually but on days 1-2 were similar between groups. Interval increases the words to first oestrus differ significantly between females, whereas ovulatory responses were similar. Thus, sexually inexperienced photo-stimulated males housed individually showed less sexual behaviour that those photo-stimulated housed in group but did not show reduced ability to induce ovulatory responses in anoestrous females; these responses resembled those induced by group-housed males.Highlights Plasma testosterone concentration is high in sexually inexperienced photo-stimulated males housed in group or individually during the rest sexual. Sexually inexperienced photo-stimulated males housed in group or individually display sexual behaviour in spring. Sexually inexperienced photo-stimulated males housed in group or individually induce sexual response in anoestrous female goats.

"The success of crocodile conservation programs highly depends on local people’s views, perceptions, and knowledge regarding these reptiles. The present study assessed these variables across the Nichupté lagoon through semi-structured interviews. Answers were grouped into three categories: thoughts regarding the presence of crocodiles in the area, locals’ perception on crocodiles, and local knowledge on crocodiles. Most of the 221 people interviewed showed no aversion to crocodiles, 93.2% knew about the presence of crocodiles in the lagoon, and 98.1% mentioned that it is essential to conserve these reptiles. On the other hand, 77.5% (men) and 70.5% (women) agreed that “it is fine” to share the lagoon with crocodiles. Concerning people’s perceptions about crocodiles, “Quiet”, “Indispensable” and “Interesting” were the most frequent answers. Regarding the local knowledge, we found a positive, statistically significant correlation between this variable and education, with those having high school degrees mentioning "Habitat" and those with college degrees mentioning "Reptile" more frequently. Conservation policies should be redesigned to include continuous environmental education programs that promote positive attitudes towards crocodile species. They should also include measures to guarantee the dissemination of necessary information to protect human and crocodile lives, is essential to consolidate conservation programs."

Sexually inexperienced male goats aged 8–21 months displayed relatively low sexual behavior when exposed to females for the first time. We aimed to determine whether i) photo-stimulation can overcome sexual inexperience in 27-month-old male goats, ii) sexually inexperienced, photo-stimulated male goats aged 27 months display the same sexual behavior as experienced goats, and iii) sexually inexperienced and experienced photo-stimulated male goats induce estrous behavior and ovulation in anestrous female goats. Five sexually inexperienced and five sexually experienced males were subjected to artificially long days (16 h of light and 8 h of darkness per day) for 2.5 months and then were exposed to females at 27 months of age (n = 50/group) for 15 days. Plasma testosterone concentrations did not differ between the two groups (P > 0.05). Sexual behavior was recorded on days 0, 1, 2, and 3 after introduction to the female groups. The inexperienced group displayed more nudging on day 2 than on days 0, 1, and 3 (P 0.05). In conclusion, sexually inexperienced or sexually experienced photo-stimulated males aged 27 months displayed high sexual behavior and stimulated estrous behavior and ovulation in anestrous female goats.

En el presente proyecto se muestra el desarrollo de programación en Matlab con la finalidad de realizar un análisis a partir de la simulación de trenes de operación aleatorios para fallas en los componentes de un sistema de distribución en Media Tensión, específicamente en dos alimentadores primarios que parten de una misma subestación y se prestan respaldo entre sí mediante dos líneas de enlace conectadas a través de dos circuitos ubicados en posición estratégica, los mismos que cuentan con un interruptor y seccionador para facilitar la transferencia de carga. El análisis de confiabilidad realizado mediante el código de programación realizado en el software Matlab está programado en forma general, es decir que ingresando los respectivos datos se puede adaptar a cualquier red; especialmente a dos alimentadores los cuales mantienen una línea de enlace para apoyo entre ambos, mejorando así su confiabilidad y reduciendo los tiempos de interrupción de servicio. El código planteado en el presente proyecto técnico se aplica a los alimentadores Centro Olmedo y Centro Sucre, pertenecientes a la Corporación Nacional de Electricidad CNEL Unidad de Negocio Esmeraldas, donde se obtuvo como resultados índices de confiabilidad lo más cercano a lo establecido por las sugerencias detalladas en las normativas internacionales, de lo que resalta los valores obtenidos tanto en el índice medio de disponibilidad del servicio y la energía media no suministrada, de los cuales se obtuvo como resultado 0.99977 y 0.001 kWh/año respectivamente.

Se presenta un registro con foto trampas sobre la depredación de nidos de cocodrilo de pantano por mapaches en la Reserva de la Biosfera Sian Ka’an, Quintana Roo, México. La depredación de nidos es una de las principales causas de mortalidad de huevos en cocodrilos. Estas imágenes fueron captadas en un nido silvestre y muestran una clara evidencia de las interacciones entre estas dos especies.

The Creole sheep in America is supposed to have originated specifically from the Iberian Peninsula and introduced by the Spaniards during the colonization. However, it is not clear their genetic relationship with Iberian breeds. The genetic origin and diversity of the Mexican Creole sheep (MCS) were investigated by mitochondrial DNA control region nucleotide sequences. DNA sequence from 33 MCS samples from three regions of México revealed 21 different haplotypes. Phylogenetic analysis including European and Iberian sheep haplotypes showed that the MCS population belongs to a differentiated and defined genetic lineage. This finding suggests that the MCS populations may be the result of a founder effect originating from a discrete Iberian population. MCS haplotypes were related to haplotypes found in the Churro Trunk and the Entrefino Trunk groups of Iberian breeds, supporting historical reports. In the Mexican genetic branch, there were also haplotypes reported from Lacaune and Awassi sheep breeds. Although it is uncertain whether a particular breed was involved as a founder of the MCS, these populations have a common phylogenetic origin.

The genetic variation in C. acutus from the Pacific coast of Mexico was investigated using mitochondrial DNA data. Overall, the localities sampled included three in the State of Guerrero and three in the State of Oaxaca, Mexico. We inferred phylogenetic and genealogical relationships, and genetic diversity was determined, using partial sequences of the mitochondrial control region. Additional published sequences from GenBank for C. acutus and C. moreletii were utilized. The results obtained from 73 crocodile sequences indicate the presence of five haplotypes grouped into two monophyletic lineages, one corresponding to C. acutus and the other to C. moreletii. The presence of C. moreletii in Chacahua (Oaxaca) was unexpected. The level of nucleotide diversity was nil and moderate in C. acutus and C. moreletii lineages, respectively, consistent with other publications concerning Crocodylia. Further studies of crocodiles in Chacahua (Oaxaca) are necessary to assess the possibility of hybridization.

El objetivo fue estimar la curva de producción de leche y determinar sus componentes químicos en ovejas Criollas Obispo. Se procesaron datos de producción de 22 ovejas con el modelo de Wood; los registros se realizaron cada semana con el método de amamantamiento-pesaje de la cría-ordeño y la determinación de la composición química se hizo con un equipo Lactichek. El pico máximo promedio de producción (539.60 g) se alcanzó en la segunda semana, con un rendimiento diario de 342.82 ± 11.59 g y producción acumulada por oveja estimada para una lactancia de 12 semanas de 30.58 ± 1.21 kg. Los promedios para proteína, grasa, lactosa, sólidos totales y sólidos no grasos fueron de 5.71%, 2.49%, 4.59%, 13.66% y 11.24%, respectivamente. La curva de producción de leche en ovejas Obispo registra su máximo incremento entre la segunda y la tercera semana posparto.

This study aimed to determine the trends in milk production, fertility, temperature-humidity index (THI), and herd size in dairy herds from the Laguna region in northern Mexico. Records of 16 dairy herds of Holstein cows from January 2002 to December 2016 were used. Milk production was categorized in low and high levels. Milk production and fertility were analyzed using generalized equation estimation procedures by a model of repeated measures that included the effect of year, month, and productive level, an interaction for month × productive level, and herd effect was nested in productive level. For THI, a generalized linear model that included the effects of year and month was used. Dairy herds with high levels of milk production yielded more milk than those with low levels (P 0.001). Milk production in 2002 and 2016 was 27.4 ± 0.6 and 32.3 ± 0.7 L/cow/day, respectively. Fertility fluctuated throughout the study. Dairy herds with high levels of milk production recorded higher fertility than those with low levels (P 0.001). From October to April, THI was 70, whereas it was 73 from May to September, indicating that cows were in heat stress (20 h/day). The median herd size was 995 and 2569 cows in 2002 and 2016, respectively. In conclusion, in large herds, milk production increased over the years of study, whereas fertility showed a wave cycle; nonetheless, when THI was 73, both milk production and fertility decreased.

espanolEl objetivo del presente estudio fue determinar la diversidad genetica del bovino criollo del noroeste de Mexico utilizando el locus DRB3.2 del Complejo Principal de Histocompatibilidad (MHC). Se tomaron muestras sanguineas de cincuenta y seis bovinos criollos en cinco localidades; en el estado de Chihuahua (Cerocahui, Guadalupe y Calvo y Cuauhtemoc) y en el estado de Baja California Sur (La Paz y Mulege). El locus BoLA-DRB3.2 fue genotipificado mediante la tecnica PCR-RFLP. Se identificaron 39 alelos, de los cuales 14 alelos no habian sido reportados previamente. El nivel de consanguinidad promedio en todas las poblaciones analizadas fue FIS= 0.09 (P EnglishThe objective of this study was to determine the genetic diversity of creole cattle in northwestern Mexico using the BoLA-DRB3.2 locus of the Major Histocompatibility Complex (MHC). A total of 56 creole cattle were sampled from five communities; in the state of Chihuahua (Cerocahui, Guadalupe y Calvo and Cuauhtemoc) and in the state of Baja California Sur (La Paz and Mulege). The BoLA-DRB3.2 locus was genotyped by PCR-RFLP assay. Thirty-nine alleles were identified, out of which 14 had not been previously reported. The average level of inbreeding in all populations analyzed was FIS= 0.09 (P francaisL’objectif de l’etude etait de determiner la diversite genetique des bovins creoles originaires du Nord-Ouest du Mexique en utilisant le locus DRB3.2 du complexe majeur d’histocompatibilite (MHC). Des echantillons de sang de 56 bovins creoles dans cinq endroits de l’Etat de Chihuahua (Cerocahui, Guadalupe y Calvo et Cuauhtemoc) et dans l’Etat de Baja California Sur (La Paz et Mulege) ont ete preleves. Le locus BoLA-DRB3.2 a ete genotype en utilisant la technique PCR-RFLP. Trente-neuf alleles ont ete identifies, dont 14 avaient deja ete signales. La differenciation genetique des populations etudiees etait de FSC= 0,068 (P

Summary Genealogical and live body weight monthly records from 790 sheep of the Chiapas breed born between 1991 and 2004 were used to characterize the growth curve and estimate (co)variance components for the parameters (A, k and b) of the Gompertz function. The pedigree structure consisted of 790 sheep, including 45 rams and 379 ewes. Estimation of (co)variance components for each growth parameter was achieved using a univariate animal model with the restricted maximum likelihood (REML) method. Estimated values of heritability were: A (adult weight) 0.21 ± 0.06; b (integration constant) 0.25 ± 0.07; k (maturity rate) 0.16 ± 0.06; age at the inflexion estimated as (ln(b)/k) 0.24 ± 0.07; and absolute growth rate as [k*(0.368*A)* ln(A/0.368*A)] 0.22 ± 0.07. The growth of males was 24% (P < 0.05) faster than that of females; adult weight was 25 ± 0.7 kg for males and 23 ± 0.7 kg for females; absolute growth was 59 ± 2 g and 44 ± 2 g per day for males and females respectively. The Chiapas breed of sheep is a small animal with a slow growth curve, probably due to its adaptation to the environmental conditions where it lives. Growth curve can be modified through selection.

The objective of the present study was to determine the accuracy and the negative prediction value of Pregnancy-Associated Glycoprotein (PAG) at 29 d post artificial insemination by ELISA. Blood serums of multiparous Holstein cows were used (n = 275). Pregnancy diagnosis was carried out by rectal palpation at 40 d and it was considered as reference test. Pregnancy results based on the PAG-ELISA and the pregnancy diagnosis at 40 d showed high concordance with a kappa value of 0.7. The accuracy test based on PAG-ELISA at 29 d post artificial insemination compared with pregnancy diagnosis by rectal palpation was 88%. The values of sensibility, specificity, positive prediction value, negative prediction value and positive and negative likelihood ratio were 96, 78, 83 and 95%, 4.5 and 0.0442, respectively. It is concluded that pregnancy diagnosis of PAG-ELISA is reliable and accurate at 29 d post artificial insemination. The PAG-ELISA's negative prediction value diminishes the number of days in subjecting cows diagnosed as nonpregnant to diverse strategies of hormonal synchronization protocols.

This study was conducted to estimate the effects of sire breed (Charollais, Dorper, Dorset, Hampshire, and Suffolk) and genetic group of the dam [local whiteface (Criolla), grade Hampshire, grade Suffolk, F(1) Dorper × Pelibuey, Australian composite, hair sheep (Barbados Blackbelly or Pelibuey), Dorset, Hampshire and Suffolk] on birth weight, survival rate from birth to weaning, and weaning weight adjusted to 65 d of age. Data were recorded from 2004 to 2006 on crossbreed lambs obtained by artificial insemination from 114 flocks in Central Mexico. High (above the mean) or low (below the mean) environmental categories were assigned to each record from flock-year-season effects solutions obtained in fixed-effects linear model analyses. Birth weights of lambs sired by Charollais rams (3.94 kg) were heavier (P 0.05) on survival rate. Sire breed × environmental category interaction effect was significant for birth weight (P 0.05) observed for survival rate.

Se analizo el impacto del fenomeno El Nino (1997-1998) sobre la dinamica espacial, asi como sobre los cambios en los patrones de agregacion de los huevos y larvas de anchoveta debido a la alteracion de las anomalias termicas. Se realizaron seis campanas bio-oceanograficas en el norte de Chile desde Arica (18°29'S, 70°19'W) a Antofagasta (23°38'S, 70°24'W) durante diferentes periodos (antes y durante) del evento El Nino 1997-1998. Se registraron cambios en la distribucion vertical y patrones de agregacion de las larvas de anchoveta, asi como un aumento de la biomasa de zooplancton con la llegada de El Nino; ademas, las preferencias ecologicas de la anchoveta fueron alteradas por el desplazamiento gradual hacia el sur de las zonas de desove como resultado de la llegada de aguas calidas subtropicales. Un aumento en la biomasa del zooplancton vinculada a un cambio en la composicion de especies sugiere un impacto negativo en la alimentacion de las larvas de anchoveta. Los resultados obtenidos indicarian que cambios bruscos en el ambiente tendrian consecuencias inmediatas en la distribucion de los estados tempranos de la anchoveta, causando un potencial impacto en el reclutamiento de esta especie pelagica en el Sistema de Corrientes de Humboldt frente al norte de Chile.

Mitochondrial DNA sequence data from a segment of the cytochrome b (cytb) gene were used to infer geographic distributions of two unnamed putative species of eastern Pacific bonefishes, Albula sp. A and Albula sp. C, both members of the A. vulpes complex. The molecular data revealed that Albula sp. C, a lineage originally identified from Panama, is distributed north to the coastal waters of central Mexico and the southern Gulf of California (Sea of Cortez). Albula sp. A, originally identified from the central Gulf of California and distributed to California, USA, is shown here to range to Mazatlan, Sinaloa, in the southern gulf where it occurs sympatrically with Albula sp. C. The distributions of the two putative species inferred from the molecular data suggest that the single available name for eastern Pacific bonefishes, Albula esuncula (Garman, 1899), originally described from larvae (leptocephali) collected off Acapulco, Guerrero, should be assigned to Albula sp. C. Morphometric and meristic ...

The polymorphism of locus BoLA-DRB3.2 of the Major Histocompatibility Complex was evaluated in two northern Mexican Creole cattle populations, Chihuahua (n = 47) and Tamaulipas (n = 51). The BoLA-DRB3.2 locus was typed by amplification and digestion with restriction endonuclease enzymes (PCR-RFLP). Fifty-two alleles were detected (28 previously reported and 24 new ones). In the Chihuahua population, 18 alleles and 5.5 effective alleles were found, while in the Tamaulipas population there were 34 and 10.8, respectively. The allele frequencies ranged from 0.011 to 0.383 in Chihuahua and from 0.010 to 0.206 in Tamaulipas. The frequencies of the new alleles in both cattle populations were low (0.010 to 0.053). The expected heterozygosity was 0.827 and 0.916, respectively, for the Chihuahua and Tamaulipas populations. Both populations presented a heterozygote deficit: [Chihuahua F IS = 0.1 (p = 0.019) and Tamaulipas F IS = 0.317 (p < 0.001)]. In conclusion, this study showed that the Mexican Creole cattle have many low-frequency alleles, several of which are exclusive to these populations. Genetic distances obtained show that the Mexican Creole cattle population is composed of independent populations, far apart from other South American Creole populations.

Summary The objective of this study was to evaluate the genetic structure of Mexican Criollo cattle populations using microsatellite genetic markers. DNA samples were collected from 168 animals from four Mexican Criollo cattle populations, geographically isolated in remote areas of Sierra Madre Occidental (West Highlands). Also were included samples from two breeds with Iberian origin: the fighting bull (n = 24) and the milking central American Criollo (n = 24) and one Asiatic breed: Guzerat (n = 32). Genetic analysis consisted of the estimation of the genetic diversity in each population by the allele number and the average expected heterozygosity found in nine microsatellite loci. Furthermore, genetic relationships among the populations were defined by their genetic distances. Our data shows that Mexican cattle populations have a relatively high level of genetic diversity based either on the mean number of alleles (10.2–13.6) and on the expected heterozygosity (0.71–0.85). The degree of observed homozygosity within the Criollo populations was remarkable and probably caused by inbreeding (reduced effective population size) possibly due to reproductive structure within populations. Our data shows that considerable genetic differentiation has been occurred among the Criollo cattle populations in different regions of Mexico.

Canine distemper virus (CDV) is a highly contagious viral pathogen of worldwide distribution that can cause lethal disease in dogs and other mammals. Genetic diversity is found among reference strains and isolates of CDV, mainly in the haemagglutinin protein (H), fusion protein (F) and nucleoprotein (N), and this may be associated with the increasing incidence of distemper in dogs. CDV was identified by RT-PCR in serum samples taken from two clinically diseased, previously vaccinated Mexican dogs. Subsequently, in both samples, a fragment of the CDV N gene was sequenced revealing a 100% identity between nucleotide sequences. However, the sequence obtained was different to that found in virus strains used in vaccines and in isolates reported elsewhere, but was closely related to A75/17, 1127/Gi95, and 2495/Gi95 sequences from USA and Germany, and clustered with 1127/Gi95 and 2495/Gi95 strains. The results suggest that a novel CDV lineage may be present in Mexico.

Nucleotide and amino acid sequence data from a 544-bp segment of the mitochondrial cytochrome B (Cytb) gene were used to examine phylogenetic relationships of the Shafted Bonefish, Albula ( = Dixonina) nemoptera, a morphologically distinct bonefish limited to the coastal waters of the eastern Pacific and western Atlantic, among members of the widely distributed and cryptic A. vulpes species complex of Albula (Albuliformes: Albulidae). Phylogenetic trees based on Bayesian and parsimony methods indicated that A. nemoptera from the tropical eastern Pacific (Colima, Mexico) nested within the A. vulpes complex, supporting the placement of the genus Dixonina Fowler, 1911 into the synonymy of Albula Scopoli, 1777. Phylogenetic analyses also showed that A. nemoptera is the sister taxon to the undescribed Albula sp. E from the western Atlantic (Bahia, Brazil), previously placed in the A. vulpes complex. This evidence, together with the presence of a diagnostic amino acid substitution in the translated Cyt...

The composition, and the temporal vertical and horizontal distribution of chaetognaths off Concepcion Bay, Chile were analyzed from 15 oceanographic stations along three sections perpendicular to the coast in April, June, November and December 1991. Oblique zooplankton tows, using 60-cm diameter Bongo nets with 350-μm mesh, were carried out to a maximum of 200 m depth. Additionally, in November and December, in the three coastal most stations of each section, stratified vertical zooplankton tows were performed in three strata (25–0, 50–25 and 100–50 m) with a WP-2 net, with 350-μm mesh provided with a flowmeter to determine the filtered volume. The community of chaetognaths showed ten species: Sagitta enflata, S. bierii, S. decipiens, S. tasmanica, S. lyra, S. minima, S. planctonis, Krohnitta subtilis, K. pacifica and Eukrohnia hamata. Of these species, S. enflata was the most abundant and frequent in both vertical and oblique samples. In vertical samples, some mesopelagic species were identified, such as E. hamata, S. decipiens, S. lyra and S. planctonis. These species were more abundant in November, when the upwelling was more intense. An inverse situation was observed in December, when the abundance of S. enflata, an epiplanktonic species, increased, associated with greater water-column stability. With exception of S. enflata, the other species had not been previously recorded in the vicinity of Concepcion Bay.

Arthrobotrys musiformis is a nematophagous fungus with potential for the biological control of Haemonchus contortus larvae. This study aimed to identify and demonstrate the proteolytic activity of extracellular products from A musiformis cultured in a liquid medium against H contortus infective larvae. A musiformis was cultured on a solid medium and further grown in a liquid medium, which was then processed through ion exchange and hydrophobic interaction chromatography. The proteolytic activity of the purified fraction was assayed with either gelatin or bovine serum albumin as substrate. Optimum proteolytic activity was observed at pH 8 and a temperature of 37°C. Results obtained with specific inhibitors suggest the enzyme belongs to the serine-dependent protease family. The purified fraction concentrate from A musiformis was tested against H contortus infective larvae. A time-dependent effect was observed with 77 per cent immobility after 48 hours incubation, with alteration of the sheath. It is concluded that A musiformis is a potential candidate for biological control because of its resistant structures and also because of its excretion of extracellular products such as proteases. The present study contributes to the identification of one of the in vitro mechanisms of action of A musiformis, namely the extracellular production of proteases against H contortus infective larvae. More investigations should be undertaken into how these products could be used to decrease the nematode population in sheep flocks under field conditions, thereby improving animal health while simultaneously diminishing the human and environmental impact of chemical-based drugs.

The bathymetric distribution of chaetognaths was studied at an oceanic station located 14 nautical miles off Valparaiso. During an annual cycle between July 1994 and September 1995, vertical samples of plankton were taken between 0 and 900 m depth. Temperature, salinity and dissolved oxygen showed temporal and spatial fluctuations within the surface layer (0–100 m), mainly affected by Subantarctic Water and in certain periods by Subtropical Water. Between 150 and 400 m low dissolved oxygen content and higher salinity were found, characteristic of Equatorial Subsurface Waters, and between 400 and 800 m Antarctic Intermediate Water, characterized by its higher content of dissolved oxygen and lower temperature and salinity was present. Fifteen species of chaetognaths were identified: Sagitta bierii, S. enflata, S. minima, S. pacifica, S. lyra, S. planctonis, S. marri, S. macrocephala, S. maxima, S. decipiens, S. tasmanica, S. gazellae, Krohnitta subtilis, Eukrohnia hamata and E. fowleri. The most abundant and frequent species were Sagitta enflata, S. bierii and Eukrohnia hamata. The greatest density of chaetognaths was confined to the 0–200 m water column and the species diversity gradually decreased from the epiplanktonic to the mesoplanktonic domain. The vertical distribution of the chaetognaths showed a strong association with the water masses present. The epipelagic species (0–200 m) S. enflata, S. bierii, S. minima and Krohnitta subtilis are associated mainly with Subantarctic Water and occasionally with Subtropical Water; the mesopelagic species (200–1000 m) S. lyra, S. planctonis, S. macrocephala, S. marri and E. fowleri are associated with Equatorial Subsurface Water and Antarctic Intermediate Water. There is another species assemblage of broad bathymetric distribution (0–900 m) consisting of E. hamata, S. decipiens and S. maxima, which does not show a distinctive association with a given water mass. E. hamata is an indicator species of upwelling events off the Chilean coast, showing an association with waters of low temperatures, greater salinity, and low contents of dissolved oxygen, which are characteristic of Equatorial Subsurface Water.

Marine protected areas of multiple uses (MPA-MU), are an important management tool to protect biodiversity and regulate the use of coastal marine resources. However, robust conservation plans require an explicit consideration of not only biological but also social components, balancing the protection of biodiversity with a sustainable exploitation of marine resources. Here we applied the decision-making algorithm MARXAN to provide a zoning analysis at the Mejillones Peninsula MPA-MU in northern Chile, one of largest MPA’s of the Humboldt Current Marine Ecosystem. We set conservation goals for coarse and fine-filter conservation targets that were crossed out against different threats and pressure factors from human activities across the area. We identified a portfolio of sites for conservation, within the Mejillones Peninsula MPA-MU, representing different ecological systems with different levels of human impacts and vulnerability. These results may serve as a foundational guideline for the future administration of the MPA-MU.

The aims of this study were to determine the frequency of egg shedding (percentage of egg-positive faecal samples) and faecal egg counts (FEC) over 13 months in two different breeds of ewes, both pregnant and non-pregnant, in a mountainous region of central Mexico. Additionally, the effect of ivermectin and albendazole treatments on FEC reduction was recorded. The study also aimed to relate temperature and rainfall to FEC. The gastrointestinal nematode (GIN) third-stage larvae genera recovered from both faeces and grassland pastures in a temperate region were also assessed. Faecal samples were collected from ewes at monthly intervals for 13 months to investigate the FEC population of GIN larvae, their concentration and genera in grass samples collected from grazed and rested pastures. Egg-shedding frequency ranged from 0 to 92% and FEC from 0 to 12,000 eggs per g faeces (epg), with counts in Suffolk higher than in Dorset ewes. The identified genera were Haemonchus, Trichostrongylus, Teladorsagia, Cooperia, Oesophagostomum, Bunostomum, Nematodirus and Strongyloides. Haemonchus and Trichostrongylus were the most common genera. The number of L3 was higher in grazing lands than in those at rest. The highest FEC were recorded in the dry season due to peripartum, but the highest L3 counts were recorded in the rainy season. The coexistence of species of different geographical distributions at this site may be because there is a confluence of Nearctic and Neotropical geographic regions; thus, despite the temperate climate, tropical species can be found. Additionally, this study suggests that increasing temperatures could favour the presence of different tropical GIN species together with typical temperate-zone GIN species.

The infectious pancreatic necrosis virus (IPNV; genus Aquabirnavirus) affects salmon and trout, causing high mortality in first-feeding fry. The classification of this virus includes nine serotypes and seven genogroups. In Mexico, two different isolates were identified in 2000 and 2008, respectively. Both isolates were classified into genogroup I according to the RNA genome of this virus. As Mexico is importing rainbow trout Oncorhynchus mykiss eggs from different countries, the aim of this study was to genotype IPNV isolates obtained from four rainbow trout producer regions within the state of Mexico. We utilized a fragment of the VP2* (outer capsid protein) gene sequence of Mexican IPNV isolates as a molecular marker to determine the genogroup to which they belong. Although all Mexican IPNV isolates were grouped into genogroup I, we identified genetic diversity among these isolates, and 14 unique nucleotide sequence types were associated with the four producer regions in Mexico State. Received ...

"El objetivo del presente estudio fue estimar parámetros de las curvas de crecimiento del peso y la longitud en el pez blanco Chirostoma estor (EE), el pez blanco pico negro Chirostoma promelas (PP) y de sus híbridos recíprocos (EP y PE) hasta los 300 días de edad a partir de un cruzamiento dialélico completo bajo condiciones de cultivo en Morelia, Michoacán, México. La longitud se midió mensualmente desde la eclosión, mientras que el peso se midió mensualmente a partir de los 120 días. Los números totales de observaciones (muestras) analizadas para longitud fueron 1006 (26), 771 (22), 513 (22) y 421 (21) para los grupos EP, PE, PP y EE, respectivamente. Los números totales de observaciones (muestras) analizadas para peso fueron 630 (16), 521 (14), 263 (13) y 256 (13) para los grupos EP, PE, PP y EE, respectivamente. Las curvas de crecimiento para peso y longitud se estimaron con modelos de regresión no lineal. El grupo EE alcanzó un peso estimado de 7.89 g a los 300 días de edad, 65% mayor que el de PP (4.78 g) y 57% mayor que el promedio de los híbridos (P < 0.01); EE tuvo una longitud de 9.31 cm (14%) mayor que PP (7.97 cm) y 13% mayor que la del promedio de los híbridos (P < 0.01). Los cuatro grupos, mostraron un crecimiento de tipo alométrico positivo con valores de 3.2 a 3.3 (P < 0.05). Los resultados de este estudio son las primeras estimaciones comparativas de las características de crecimiento hasta los 300 días de edad para estas especies y sus híbridos en cautiverio."

Canine Distemper is a highly contagious viral systemic disease that affects a wide variety of terrestrial carnivores. Canine Distemper virus (CDV) appears genetically heterogeneous, markedly in the hemagglutinin protein (H), showing geographic patterns of diversification that are useful to monitor CDV molecular epidemiology. In Mexico the activity of canine distemper remains high in dogs, likely because vaccine prophylaxis coverage in canine population is under the levels required to control effectively the disease. By phylogenetic analysis based on the nucleoprotein (N) and on the H genes, Mexican CDV strains collected between 2007 and 2010 were distinguished into several genovariants, all which constituted a unique group, clearly distinct from field and vaccine strains circulating worldwide, but resembling a CDV strain, 19876, identified in Missouri, USA, 2004, that was genetically unrelated to other North-American CDV strains. Gathering information on the genetic heterogeneity of CDV on a global scale appears pivotal in order to investigate the origin and modalities of introduction of unusual/novel CDV strains, as well as to understand if vaccine breakthroughs or disease epidemics may be somewhat related to genetic/antigenic or biological differences between field and vaccine strains.

The objective of this study was to assess the correlation among traits associated with resistance or susceptibility to Haemonchus contortus infestation and to evaluate the participation of the ovine major histocompatibility complex (MHC) in Pelibuey sheep, a prevalent breed in tropical and sub-tropical regions in Mexico and elsewhere. Association among the fecal egg count (FEC), blood packed cell volume (PCV), antibody (AB) levels, serum proteins (SP) and blood eosinophil count (EOS) was assessed in 52 lambs experimentally infected with H. contortus, and the participation of the MHC was evaluated using polymorphisms in three microsatellites, located at the class I (OMHC1) and class II (OLADRB1, OLADRB2) regions of the MHC. Spearman correlation analysis among the traits showed a negative association (P

All major ABO blood alleles are found in most populations worldwide, whereas the majority of Native Americans are nearly exclusively in the O group. O allele molecular characterization could aid in elucidating the possible causes of group O predominance in Native American populations. In this work, we studied exon 6 and 7 sequence diversity in 180 O blood group individuals from four different Mesoamerican populations. Additionally, a comparative analysis of genetic diversity and population structure including South American populations was performed. Results revealed no significant differences among Mesoamerican and South American groups, but showed significant differences within population groups attributable to previously detected differences in genetic drift and founder effects throughout the American continent. Interestingly, in all American populations, the same set of haplotypes O(1), O(1v), and O(1v(G542A)) was present, suggesting the following: (1) that they constitute the main genetic pool of the founding population of the Americas and (2) that they derive from the same ancestral source, partially supporting the single founding population hypothesis. In addition, the consistent and restricted presence of the G542A mutation in Native Americans compared to worldwide populations allows it to be employed as an Ancestry informative marker (AIM). Present knowledge of the peopling of the Americas allows the prediction of the way in which the G542A mutation could have emerged in Beringia, probably during the differentiation process of Asian lineages that gave rise to the founding population of the continent.

The presence of infectious pancreatic necrosis virus (IPNV) in salmonids predominantly produces a high mortality rate in first-feeding fry. Genomic analysis of the vp2 gene sequence is most commonly used to determine the genetic diversity of IPNV isolates. Recently, information obtained from the vp1 gene allowed for efficient analysis of the genetic diversity of IPNV. In this study, the vp1 gene from a Mexican IPNV isolate was characterized and compared with IPNV isolates from Europe, North America, and Asia. The results indicate that the Mexican isolate is most closely related genetically to the 2310 strain from Spain.

"El objetivo fue evaluar la respuesta de la administración de gonadorelina (GnRH) en el día 5, y en el día 11 postinseminación, sobre las concentraciones de progesterona plasmática y las tasas de concepción en vacas repetidoras Holstein en condiciones de estrés calórico. Se conformaron al azar tres grupos: 1) 100 ¿g de gonadorelina en el día 5 (GnRH-5; n=33); 2) misma dosis en el día 11 (GnRH-11; n=34) postinseminación, y 3) un grupo testigo (no GnRH; n=34). Se obtuvieron muestras sanguíneas en los días 8, 11, 14, 17, 20 y 23 postinseminación para la determinación de la concentración de progesterona plasmática (P4) mediante RIA. El diagnóstico de preñez fue por palpación rectal en el día 43 ± 3 postinseminación. Las concentraciones de P4 fueron mayores para el tratamiento GnRH-5 en el día 11 postinseminación (P0.05), GnRH-5 (4/33; 12.1 %), GnRH-11 (4/34; 11.8 %) y testigo (5/34; 14.7 %). Las vacas fueron inseminadas con un Índice de temperatura-humedad de ¿ 72 unidades, que indica que se encontraban en condiciones de estrés calórico. Se concluye que con la administración de GnRH en el día 5 se elevaron las concentraciones plasmáticas de progesterona pero no se incrementaron las tasas de concepción en vacas repetidoras Holstein con estrés calórico."