Genetic variability and population structure of the Montezuma quail (Cyrtonyx montezumae) in the northern limit of its distribution.

Restricted movement among populations decreases genetic variation, which may be the case for the Montezuma quail (Cyrtonyx montezumae), a small game bird that rarely flies long distances. In the northern limit of its distribution, it inhabits oak-juniper-pine savannas of Arizona, New Mexico, and Texas. Understanding genetic structure can provide information about the demographic history of populations that is also important for conservation and management. The objective of this study was to determine patterns of genetic variation in Montezuma quail populations using nine DNA microsatellite loci. We genotyped 119 individuals from four study populations: Arizona, Western New Mexico, Central New Mexico, and West Texas. Compared to other quail, heterozygosity was low (H¯0 = 0.22 ± 0.04) and there were fewer alleles per locus (A = 2.41 ± 0.27). The global population genetic differentiation index RST = 0.045 suggests little genetic structure, even though a Bayesian allocation analysis suggested three genetic clusters (K = 3). This analysis also suggested admixture between clusters. Nevertheless, an isolation-by-distance analysis indicates a strong correlation (r = 0.937) and moderate evidence (P = 0.032) of non-independence between geographical and genetic distances. Climate change projections indicate an increase in aridity for this region, especially in temperate ecosystems where the species occurs. In this scenario, corridors between the populations may disappear, thus causing their complete isolation.

Morphometry and meristics of two species of Ictalurus (Siluriformes: Ictaluridae), native catfishes of Sierra Madre Occidental, Mexico

Introduction: Morphotypes of native catfish of the genus Ictalurus (Siluriformes: Ictaluridae) are known to occur in allopatry in the northern Sierra Madre Occidental of Mexico, with only the Yaqui catfish (Ictalurus pricei) taxonomically described. Recent genetic analysis of these morphotypes has revealed the monophyly of the I. pricei complex, which indicates Ictalurus sp. from the Culiacán River and San Lorenzo River basins as its nearest genetic relative and recognizes as an evolutionarily significant unit the Culiacán River and San Lorenzo River morphotypes. Objective: To compare the meristic and morphometric characteristics of the catfish of the Culiacán River basin with its nearest genetic relative, the Yaqui catfish, in order to determine the presence of distinctive morphological characters that support genetic evidence previously reported for these morphotypes. Methods: Catfish specimens were collected during various field expeditions (1990-2012) to remote sites of the Sierra Madre Occidental and conducted in the Yaqui River and Culiacán River basins with the purpose of morphological comparison. Forty-five morphological characters (40 morphometric and five meristic) were examined in 76 adult specimens - 52 Ictalurus sp. and 24 Ictalurus pricei. Three groups were subject to a discriminant function analysis (DFA), including two Ictalurus sp. groups from the Humaya River and Tamazula River sub-basins, representing the Culiacán River basin, and one I. pricei group representing the Yaqui River basin. The standardized measurements and meristic data of the catfish morphotypes were compared by means of DFA. Results: The DFA revealed 12 characters to be significantly different (P< 0.01) among the groups compared. The morphological characters separating the Ictalurus sp. (Culiacán River basin) from the Yaqui catfish were associated with lower anal, pelvic and pectoral fin ray numbers, shorter head and predorsal lengths, shorter longest lateral barbel and longest dorsal ray lengths and a narrower premaxilar dentary plate; and finally longer distances in Ictalurus sp. for dorsal-fin origin to last anal-fin ray base and dorsal-fin origin to posterior end of the adipose fin base. The standardized coefficients for canonical variables 1 and 2 accounted for 85.6 % and 14.4 % of the total variation, respectively. Conclusions: The distinctive morphological characters of the Ictalurus sp. found in the Culiacán River basin, combined with the known mitochondrial evidence for this morphotype, identify it as an evolutionarily significant unit that requires description as a new species based on taxonomical protocols.

Introducción: Morfotipos de bagres nativos del género Ictalurus (Siluriformes: Ictaluridae) se distribuyen de manera alopátrica en el norte de la Sierra Madre Occidental, de los cuales solo el bagre Yaqui (Ictalurus pricei) ha sido taxonómicamente descrito. Análisis genéticos recientes de esos morfotipos han revelado la monofilia del complejo I. pricei, que incluyó a Ictalurus sp. de las cuencas de los ríos Culiacán y San Lorenzo como su pariente genético más cercano, además del reconocimiento de los morfotipos de los ríos Culiacán and San Lorenzo como una unidad evolutivamente significativa. Objetivo: Comparar características merísticas y morfométricas del bagre de la cuenca del río Culiacán con su pariente genético más cercano, el bagre Yaqui, con el propósito de determinar la presencia de caracteres morfológicos distintivos en apoyo a evidencia genética previamente reportada para esos morfotipos. Métodos: Especímenes de bagres fueron recolectados durante varias expediciones de campo (1990-2012) en sitios remotos de la Sierra Madre Occidental en las cuencas de los ríos Yaqui y Culiacán para comparación morfológica. Cuarenta y cinco caracteres morfológicos (40 morfométricos y cinco merísticos) fueron examinados en 76 especímenes adultos (52 de Ictalurus sp. y 24 de Ictalurus pricei). Medidas corporales estandarizadas y datos merísticos de los morfotipos de bagres estudiados fueron comparados por medio de un análisis de función discriminante (AFD). Resultados: El AFD arrojó 12 caracteres significativamente diferentes (P< 0.01) entre los grupos comparados. Los caracteres morfológicos que distinguen al bagre del río Culiacán del bagre Yaqui, estuvieron asociados con un menor número de radios anales, pélvicos y pectorales, así como dimensiones más pequeñas para la longitud de la cabeza, longitud predorsal, longitud de la barbilla lateral más larga, longitud del radio dorsal más largo y una menor anchura de la placa dentaria premaxilar; y finalmente, dimensiones mayores en Ictalurus sp. (cuenca del río Culiacán) para distancias como origen de aleta dorsal a la base del último radio anal y origen de aleta dorsal a conexión posterior de aleta adiposa. Los coeficientes estandarizados para las variables canónicas 1 y 2 explicaron el 85.6 y 14.4 % de la variación total, respectivamente. Conclusiones: Los caracteres morfológicos distintivos de Ictalurus sp. de la cuenca del río Culiacán, en combinación con la evidencia mitocondrial conocida para este mismo morfotipo, permite reconocerlo como una unidad evolutivamente significativa y que requiere ser descrita como una especie nueva bajo los protocolos taxonómicos.

Prevalence and genotypic diversity of ostreid herpesvirus type 1 in Crassostrea gigas cultured in the Gulf of California, Mexico.

In bivalve mollusk aquaculture, massive disease outbreaks with high mortality and large economic losses can occur, as in northwest Mexico in the 1990s. A range of pathogens can affect bivalves; one of great concern is ostreid herpesvirus 1 (OsHV-1), of which there are several strains. This virus has been detected in the Gulf of California in occasional or sporadic samplings, but to date, there have been few systematic studies. Monthly samples of Crassostrea gigas, water, and sediment were taken in the La Cruz coastal lagoon and analyzed by PCR. The native mollusk, Dosinia ponderosa, which lives outside the lagoon, was sampled as a control. The virus was found throughout the year only in C. gigas, with prevalence up to 60%. In total, 9 genotype variants were detected, and genetic analysis suggests that linear genotypic evolution has occurred from strain JF894308, present in La Cruz in 2011. There has been no evidence of the entry of new viral genotypes in the recent past, thus confinement of the virus within the lagoons of the Gulf of California could promote a native genotypic diversity in the short term.

A multilocus phylogeny of the fish genus Poeciliopsis: Solving taxonomic uncertainties and preliminary evidence of reticulation.

The fish genus Poeciliopsis constitutes a valuable research system for evolutionary ecology, whose phylogenetic relationships have not been fully elucidated. We conducted a multilocus phylogenetic study of the genus based on seven nuclear and two mitochondrial loci with a thorough set of analytical approaches, that is, concatenated (also known as super-matrix), species trees, and phylogenetic networks. Although several relationships remain unresolved, the overall results uncovered phylogenetic affinities among several members of this genus. A population previously considered of undetermined taxonomic status could be unequivocally assigned to P. scarlli; revealing a relatively recent dispersal event across the Trans-Mexican Volcanic Belt (TMVB) or Pacific Ocean, which constitute a strong barrier to north-south dispersal of many terrestrial and freshwater taxa. The closest relatives of P. balsas, a species distributed south of the TMVB, are distributed in the north; representing an additional north-south split in the genus. An undescribed species of Poeciliopsis, with a highly restricted distribution (i.e., a short stretch of the Rio Concepcion; just south of the US-Mexico border), falls within the Leptorhaphis species complex. Our results are inconsistent with the hypothesis that this species originated by "breakdown" of an asexual hybrid lineage. On the other hand, network analyses suggest one or more possible cases of reticulation within the genus that require further evaluation with genome-wide marker representation and additional analytical tools. The most strongly supported case of reticulation occurred within the subgenus Aulophallus (restricted to Central America), and implies a hybrid origin for P. retropinna (i.e., between P. paucimaculata and P. elongata). We consider that P. balsas and P. new species are of conservation concern.

Complete mitochondrial genome of Ictalurus pricei (Teleostei: Ictaluridae) and evidence of a cryptic Ictalurus species in Northwest Mexico.

The nominal Yaqui catfish, Ictalurus pricei, is a species of Ictaluridae (Siluriformes) often recorded from Northwest Mexico. Southern distribution members of the I. pricei complex in Northwest Mexico include at least one undescribed species that differs from Yaqui catfish in morphological features, herein called "Sinaloa Catfish". Sequencing of four geographical mitogenome haplotypes of Yaqui catfish and Sinaloa catfish showed geographical haplotypes of I. pricei within a clade of specific identity, close to Sinaloa catfish haplotypes. Our molecular phylogeny represents a working hypothesis supporting information on the evolutionary relationships of the Ictalurus species from Western Mexico and Western USA.

G-C heterozygosis in mutS homolog2 as a risk factor to hereditary nonpolyposis colon cancer in the absence of a family medical history.

To detect the presence of point mutations in a small section of the mutS homolog2 (MSH2) gene in both healthy and affected persons treated at the General Hospital of the State of Sonora, a 353 base pair section of the MSH2 gene was amplified and sequenced from six persons affected by hereditary nonpolyposis colorectal cancer and from 19 healthy persons. The affected persons did not show the mutations reported in the scientific literature; however, six healthy persons were heterozygote and mutant-allele carriers. The heterozygote condition implies that carriers are candidates for the development of colorectal cancer. However, it is important to know the family medical history when investigating hereditary mutations.

Catalytic subunits atpα and atpß from the Pacific white shrimp Litopenaeus vannamei F(O)F (1) ATP-synthase complex: cDNA sequences, phylogenies, and mRNA quantification during hypoxia.

In the mitochondrial F(O)F(1) ATP-synthase/ATPase complex, subunits α and ß are part of the extrinsic portion that catalyses ATP synthesis. Since there are no reports about genes and proteins from these subunits in crustaceans, we analyzed the cDNA sequences of both subunits in the whiteleg shrimp Litopenaeus vannamei and their phylogenetic relationships. We also investigated the effect of hypoxia on shrimp by measuring changes in the mRNA amounts of atpα and atpß. Our results confirmed highly conserved regions for both subunits and underlined unique features among others. The ATPß deduced protein of shrimp was less conserved in size and sequence than ATPα. The relative mRNA amounts of atpα and atpß changed in shrimp pleopods; hypoxia at 1.5 mg/L caused an increase in atpß transcripts and a subsequent decrease when shrimp were re-oxygenated. Results confirm that changes in the mRNAs of the ATP-synthase subunits are part of the mechanisms allowing shrimp to deal with the metabolic adjustment displayed to tolerate hypoxia.

Functional identity of the active sites of crustacean and viral thymidylate synthases.

Thymidylate synthase (TS) catalyzes the synthesis of deoxythymidine monophosphate (dTMP), which is an essential precursor for DNA synthesis. The rationale underlying drug design is to identify compounds that differentially inhibit a viral or parasite enzyme vs. the host homologue. We studied the TS of the white spot syndrome virus (WSSV TS) and the corresponding TS from the host, the marine invertebrate shrimp Litopenaeus vannamei. TS is the only de novo source of dTMP and is essential for host and viral DNA replication. To establish proof of principle, we cloned a full-length TS cDNA from the white shrimp L. vannamei (shrimp TS) that corresponds to a deduced sequence of 289 amino acids and over-expressed it to study inhibition of both shrimp and viral TSs. Steady-state kinetic parameters for both TSs are similar, and dissociation (K(d)) or half maximal inhibitory concentration constants (IC(50)) did not show differential inhibition between the folate analogues. Differences in their amino acid sequence are not reflected in theoretical molecular models of both TSs, since both appear to have identical active sites. These results suggest that the eukaryotic TS active site is very constrained into the functional residues involved in reductive methylation of 2'-deoxyuridine-5'-monophosphate (dUMP).

The complete mitochondrial genomes of the yellowleg shrimp Farfantepenaeus californiensis and the blue shrimp Litopenaeus stylirostris (Crustacea: Decapoda).

Mitochondria play key roles in many cellular processes. Description of penaeid shrimp genes, including mitochondrial genomes are fairly recent and some are focusing on commercially important shrimp as the Pacific shrimp Litopenaeus vannamei that is being used for aquaculture not only in America, but also in Asia. Much less is known about other Pacific shrimp such as the yellowleg shrimp Farfantepenaeus californiensis and the blue shrimp Litopenaeus stylirostris. We report the complete mitogenomes from these last two Pacific shrimp species. Long DNA fragments were obtained by PCR and then used to get internal fragments for sequencing. The complete F. californiensis and L. stylirostris mtDNAs are 15,975 and 15,988 bp long, containing the 37 common sequences and a control region of 990 and 999 bp, respectively. The gene order is identical to that of the tiger shrimp Penaeus monodon. Secondary structures for the 22 tRNAs are proposed and phylogenetic relationships for selected complete crustacean mitogenomes are included. Phylogenomic relationships among five shrimp show strong statistical support for the monophyly of the genus across the analysis. Litopenaeus species define a clade, with close relationship to Farfantepenaeus, and both clade with the sister group of Penaeus and Fenneropenaeus.