Karyotypic Reshuffling in the Genus Rhipidomys (Rodentia: Cricetidae: Sigmodontinae) Revealed by Zoo-FISH.

INTRODUCTION: Rhipidomys is the second most specious and the most widespread genus of the tribe Thomasomyini. Chromosomal data have been an important tool in the taxonomy of the group that presents low variability of diploid number (2n) and highly variable fundamental numbers (FNs). Despite such diversity, the genus has been studied mainly by classical and banding cytogenetic techniques. METHODS: This study performed a comparative study between R. emiliae (2n = 44, FN = 52), R. macrurus (2n = 44, FN = 49), R. nitela (2n = 50, FN = 71), and R. mastacalis (2n = 44, FN = 72) using chromosome painting probes of two Oryzomyini species. RESULTS: Our analysis revealed pericentric inversion as the main rearrangement involved in the karyotype evolution of the group, although tandem fusions/fissions were also detected. In addition, we detected eight syntenic associations exclusive of the genus Rhipidomys, and three syntenic associations shared between species of the tribe Thomasomyini and Oryzomyini. CONCLUSION: Comparative cytogenetic analysis by ZOO-FISH on genus Rhipidomys supports a pattern of chromosomal rearrangement already suggested by comparative G-banding. However, the results suggest that karyotype variability in the genus could also involve the occurrence of an evolutionary new centromere.

New Karyotype Information for Ctenomys (Rodentia: Ctenomyidae) from Midwest and Northern Brazil.

INTRODUCTION: Its wide karyotypic variation characterizes the genus Ctenomys, and in Brazil, the genus is distributed in the country's southern, Midwest, and northern regions. Recently, populations of Ctenomys have been found in the Midwest and northern Brazil, with two new lineages named C. sp. "xingu" and C. sp. "central." METHODS: This work combines classical cytogenetic and molecular analyses to provide new chromosomal information on the boliviensis group distributed in northern and Midwestern Brazil. This includes the validation of the karyotype of C. bicolor and C. nattereri and the description of the karyotype of C. sp. "xingu" and C. sp. "central." RESULTS: We found three different karyotypes: 2n = 40 for C. bicolor; 2n = 36 for C. nattereri, and specimens from a locality belonging to C. sp. "central"; 2n = 34 for the lineage C. sp. "xingu" and specimens from a locality belonging to C. sp. "central." Furthermore, GTG banding revealed homologous chromosomes between species/lineages and allowed the identification of the rearrangements that occurred, which proved the occurrence of fissions. CONCLUSION: Considering our results on the variation of 2n in the boliviensis group, we found two possibilities: the first, deduced by parsimony, is that 2n = 36 appeared initially, and two fissions produced gave rise to 2n = 40, and an independent fusion gave rise to 2n = 34 from 2n = 36; moreover, the second explanation is that all karyotypes arose independently.

DNA Organization along Pachytene Chromosome Axes and Its Relationship with Crossover Frequencies.

During meiosis, the number of crossovers vary in correlation to the length of prophase chromosome axes at the synaptonemal complex stage. It has been proposed that the regular spacing of the DNA loops, along with the close relationship of the recombination complexes and the meiotic axes are at the basis of this covariation. Here, we use a cytogenomic approach to investigate the relationship between the synaptonemal complex length and the DNA content in chicken oocytes during the pachytene stage of the first meiotic prophase. The synaptonemal complex to DNA ratios of specific chromosomes and chromosome segments were compared against the recombination rates obtained by MLH1 focus mapping. The present results show variations in the DNA packing ratios of macro- and microbivalents and also between regions within the same bivalent. Chromosome or chromosome regions with higher crossover rates form comparatively longer synaptonemal complexes than expected based on their DNA content. These observations are compatible with the formation of higher number of shorter DNA loops along meiotic axes in regions with higher recombination levels.

Novel Complex Unbalanced Dicentric X-Autosome Rearrangement in a Thoroughbred Mare with a Mild Effect on the Phenotype.

Complex structural X chromosome abnormalities are rare in humans and animals, and not recurrent. Yet, each case provides a fascinating opportunity to evaluate X chromosome content and functional status in relation to the effect on the phenotype. Here, we report the first equine case of a complex unbalanced X-autosome rearrangement in a healthy but short in stature Thoroughbred mare. Studies of about 200 cells by chromosome banding and FISH revealed an abnormal 2n = 63,X,der(X;16) karyotype with a large dicentric derivative chromosome (der). The der was comprised of normal Xp material, a palindromic duplication of Xq12q21, and a translocation of chromosome 16 to the inverted Xq12q21 segment by the centromere, whereas the distal Xq22q29 was deleted from the der. Microsatellite genotyping determined a paternal origin of the der. While there was no option to experimentally investigate the status of X chromosome inactivation (XCI), the observed mild phenotype of this case suggested the following scenario to retain an almost normal genetic balance: active normal X, inactivated X-portion of the der, but without XCI spreading into the translocated chromosome 16. Cases like this present unique resources to acquire information about species-specific features of X regulation and the role of X-linked genes in development, health, and disease.

Karyotypic divergence reveals that diversity in the Oecomys paricola complex (Rodentia, Sigmodontinae) from eastern Amazonia is higher than previously thought.

The genus Oecomys (Rodentia, Sigmodontinae) is distributed from southern Central America to southeastern Brazil in South America. It currently comprises 18 species, but multidisciplinary approaches such as karyotypic, morphological and molecular studies have shown that there is a greater diversity within some lineages than others. In particular, it has been proposed that O. paricola constitutes a species complex with three evolutionary units, which have been called the northern, eastern and western clades. Aiming to clarify the taxonomic status of O. paricola and determine the relevant chromosomal rearrangements, we investigated the karyotypes of samples from eastern Amazonia by chromosomal banding and FISH with Hylaeamys megacephalus (HME) whole-chromosome probes. We detected three cytotypes for O. paricola: A (OPA-A; 2n = 72, FN = 75), B (OPA-B; 2n = 70, FN = 75) and C (OPA-C; 2n = 70, FN = 72). Comparative chromosome painting showed that fusions/fissions, translocations and pericentric inversions or centromeric repositioning were responsible for the karyotypic divergence. We also detected exclusive chromosomal signatures that can be used as phylogenetic markers. Our analysis of karyotypic and distribution information indicates that OPA-A, OPA-B and OPA-C are three distinct species that belong to the eastern clade, with sympatry occurring between two of them, and that the "paricola group" is more diverse than was previously thought.

Guanylate binding proteins contained in the murine chromosome 3 are important to control mycobacterial infection.

Guanylate binding proteins (GBPs) are important effector molecules of autonomous response induced by proinflammatory stimuli, mainly IFNs. The murine GBPs clustered in chromosome 3 (GBPchr3) contains the majority of human homologous GBPs. Despite intense efforts, mycobacterial-promoted diseases are still a major public health problem. However, the combined importance of GBPchr3 during mycobacterial infection has been overlooked. This study addresses the influence of the GBPchr3 in host immunity against mycobacterial infection to elucidate the relationship between cell-intrinsic immunity and triggering of an efficient anti-mycobacterial immune response. Here we show that all GBPchr3 are up-regulated in lungs of mice during Mycobacterium bovis BCG infection, resembling tissue expression of IFN-γ. Mice deficient in GBPchr3 (GBPchr3-/- ) were more susceptible to infection, displaying diminished expression of autophagy-related genes (LC3B, ULK1, and ATG5) in lungs. Additionally, there was reduced proinflammatory cytokine production complementary to diminished numbers of myeloid cells in spleens of GBPchr3-/- . Higher bacterial burden in GBPchr3-/- animals correlated with increased number of tissue granulomas. Furthermore, absence of GBPchr3 hampered activation and production of TNF-α and IL-12 by dendritic cells. Concerning macrophages, lack of GBPs impaired their antimicrobial function, diminishing autophagy induction and intracellular killing efficiency. In contrast, single GBP2 deficiency did not contribute to in vivo bacterial control. In conclusion, this study shows that GBPchr3 are important not only to stimulate cell-intrinsic immunity but also for inducing an efficient immune response to control mycobacterial infection in vivo.

Chromosomal phylogeny and comparative chromosome painting among Neacomys species (Rodentia, Sigmodontinae) from eastern Amazonia.

BACKGROUND: The Neacomys genus is predominantly found in the Amazon region, and belongs to the most diverse tribe of the Sigmodontinae subfamily (Rodentia, Cricetidae, Oryzomyini). The systematics of this genus and questions about its diversity and range have been investigated by morphological, molecular (Cytb and COI sequences) and karyotype analysis (classic cytogenetics and chromosome painting), which have revealed candidate species and new distribution areas. Here we analyzed four species of Neacomys by chromosome painting with Hylaeamys megacephalus (HME) whole-chromosome probes, and compared the results with two previously studied Neacomys species and with other taxa from Oryzomyini and Akodontini tribes that have been hybridized with HME probes. Maximum Parsimony (MP) analyses were performed with the PAUP and T.N.T. software packages, using a non-additive (unordered) multi-state character matrix, based on chromosomal morphology, number and syntenic blocks. We also compared the chromosomal phylogeny obtained in this study with molecular topologies (Cytb and COI) that included eastern Amazonian species of Neacomys, to define the phylogenetic relationships of these taxa. RESULTS: The comparative chromosome painting analysis of the seven karyotypes of the six species of Neacomys shows that their diversity is due to 17 fusion/fission events and one translocation, pericentric inversions in four syntenic blocks, and constitutive heterochromatin (CH) amplification/deletion of six syntenic autosomal blocks plus the X chromosome. The chromosomal phylogeny is consistent with the molecular relationships of species of Neacomys. We describe new karyotypes and expand the distribution area for species from eastern Amazonia and detect complex rearrangements by chromosome painting among the karyotypes. CONCLUSIONS: Our phylogeny reflects the molecular relationships of the Akodontini and Oryzomyini taxa and supports the monophyly of Neacomys. This work presents new insights about the chromosomal evolution of this group, and we conclude that the karyotypic divergence is in accord with phylogenetic relationships.

The influence of chromosome 4 on metabolism and spatial memory in SHR and SLA16 rat strains.

The Spontaneously Hypertensive Rat (SHR) has been proposed as a good model to study the pathways related to neurodegenerative diseases and glucose intolerance. Our research group developed the SLA16 (SHR.LEW-Anxrr16) congenic strain, which is genetically identical to the SHR strain, except for a locus on chromosome 4 (DGR). We applied in silico analysis on DGR to evaluate the association of their genes with neurobiological and metabolic pathways. After, we characterized cholesterol, triglycerides, metabolism of glucose and the behavioral performance of young (2 months old) and adult (8 months old) SHR and SLA16 rats in the open field, object location and water maze tasks. Finally, naïve young rats were repeatedly treated with metformin (200 mg/kg; v.o.) and evaluated in the same tests. Bioinformatics analysis showed that DGR presents genes related to glucose metabolism, oxidative damage and neurodegenerative diseases. Young SLA16 presented higher cholesterol, triglycerides, glucose and locomotion in the open field than SHR rats. In adulthood, SLA16 rats presented high triglycerides and locomotion in the open field and impairment on spatial learning and memory. Finally, the treatment with metformin decreased the glucose tolerance curve and also improved long-term memory in SLA16 rats. These results indicate that DGR presents genes associated with metabolic pathways and neurobiological processes that may produce alterations in glucose metabolism and spatial learning/memory. Therefore, we suggest that SHR and SLA16 strains could be important for the study of genes and subsequent mechanisms that produce metabolic glucose alterations and age-related cognitive deficits.

Karyotype, evolution and phylogenetic reconstruction in Micronycterinae bats with implications for the ancestral karyotype of Phyllostomidae.

BACKGROUND: The Micronycterinae form a subfamily of leaf-nosed bats (Phyllostomidae) that contains the genera Lampronycteris Sanborn, 1949, and Micronycteris Gray, 1866 (stricto sensu), and is characterized by marked karyotypic variability and discrepancies in the phylogenetic relationships suggested by the molecular versus morphological data. In the present study, we investigated the chromosomal evolution of the Micronycterinae using classical cytogenetics and multidirectional chromosome painting with whole-chromosomes probes of Phyllostomus hastatus and Carollia brevicauda. Our goal was to perform comparative chromosome mapping between the genera of this subfamily and explore the potential for using chromosomal rearrangements as phylogenetic markers. RESULTS: The Micronycterinae exhibit great inter- and intraspecific karyotype diversity, with large blocks of telomere-like sequences inserted within or adjacent to constitutive heterochromatin regions. The phylogenetic results generated from our chromosomal data revealed that the Micronycterinae hold a basal position in the phylogenetic tree of the Phyllostomidae. Molecular cytogenetic data confirmed that there is a low degree of karyotype similarity between Lampronycteris and Micronycteris specimens analyzed, indicating an absence of synapomorphic associations in Micronycterinae. CONCLUSIONS: We herein confirm that karyotypic variability is present in subfamily Micronycterinae. We further report intraspecific variation and describe a new cytotype in M. megalotis. The cytogenetic data show that this group typically has large blocks of interstitial telomeric sequences that do not appear to be correlated with chromosomal rearrangement events. Phylogenetic analysis using chromosome data recovered the basal position for Micronycterinae, but did not demonstrate that it is a monophyletic lineage, due to the absence of common chromosomal synapomorphy between the genera. These findings may be related to an increase in the rate of chromosomal evolution during the time period that separates Lampronycteris from Micronycteris.

Identification of two independent X-autosome translocations in closely related mammalian (Proechimys) species.

Multiple sex chromosome systems have been described for several mammalian orders, with different species from the same genus sharing the same system (e.g., X1X2Y or XY1Y2). This is important because the translocated autosome may be influenced by the evolution of the recipient sex chromosome, and this may be related to speciation. It is often thought that the translocation of an autosome to a sex chromosome may share a common origin among phylogenetically related species. However, the neo-X chromosomes of Proechimys goeldii (2n = 24♀, 25♂/NFa = 42) and Proechimys gr. goeldii (2n = 16♀, 17♂/NFa = 14) have distinct sizes and morphologies that have made it difficult to determine whether they have the same or different origins. This study investigates the origins of the XY1Y2 sex chromosome determination system in P. goeldii (PGO) and P. gr. goeldii (PGG) and elucidates the chromosomal rearrangements in this low-diploid-number group of Proechimys species. Toward this end, we produced whole-chromosome probes for P. roberti (PRO; 2n = 30♂/NFa = 54) and P. goeldii (2n = 25♂/NFa = 42) and used them in comparative chromosomal mapping. Our analysis reveals that multiple translocations and inversions are responsible for the karyotype diversity of these species, with only three whole-chromosomes conserved between PRO and PGO and eight between PGO and PGG. Our data indicate that multiple sex chromosome systems have originated twice in Proechimys. As small populations are prone to the fixation of chromosomal rearrangements, we speculate that biological features of Rodentia contribute to this fixation. We also highlight the potential of these rodents as a model for studying sex chromosome evolution.

Integrative analysis of chromosome banding, telomere localization and molecular genetics in the highly variable Ctenomys of the Corrientes group (Rodentia; Ctenomyidae).

The genus Ctenomys comprises about 70 species with great chromosome diversity. The Corrientes group is one of the most chromosomally variable lineages in the genus, where the diploid number (2n) varies from 41 to 70. In this group, three nominal species and numerous polymorphic and polytypic populations have been described. In order to get insight into the chromosomal evolution of this species complex, we applied different banding and molecular cytogenetic techniques. The results were interpreted in an evolutionary context, based on mitochondrial cytochrome b analyses. Studied samples are representative of the broad chromosomal variability in the group, including specimens with 2n = 42 to 2n = 70. Heterochromatin was scarce but concentrated in a few chromosomes. Centromeric DAPI-negative heterochromatin was observed in some autosomal pairs, which differed among populations. Location and amount of DAPI-neutral heterochromatin within the Y chromosome varied among populations. The variable distribution of heterochromatin indicates its dynamic behavior. NORs were detected in one pair of autosomes, which also differed among some populations. Telomeric FISH signals were observed in all complements only at the chromosome ends. The Corrientes group belongs to a clade that also includes C. pearsoni, C. lami, C. minutus, C. ibicuiensis and C. torquatus. Almost all of these species are variable at the chromosomal level, suggesting that this is the ancestral condition of the clade. Within the Corrientes group, the observed low genetic divergence, in contrast with its high chromosomal variability, is indicative of decoupling between the rates of chromosomal and mitochondrial evolution.

Terminal 13p deletion in squirrel monkey (Saimiri sciureus) with differentiated phenotype.

BACKGROUND: The taxonomic classification of squirrel monkeys is often controversial issue offering many different information. The classification of captive animals is difficult due to the phenotypic similarities between the presented species, which is observed mainly in coat coloration. METHODS: The objective of this study was to analyze the chromosome pattern of one squirrel monkey with off standard physical characteristics, which is kept in the Laboratory Animals Breeding Center in Rio de Janeiro State, Brazil, and try to establish some correlations. Chromosomes were obtained using lymphocyte culture technique. RESULTS AND CONCLUSIONS: Evaluation of G bands showed a terminal deletion in one chromosome of pair 13. The association of the results found with the different phenotypic characteristics led us to classify it as a Saimiri sciureus specimen with a structural chromosomal change, possibly allowing the expression of hemizygous alleles.

Photobiomodulation effects on mRNA levels from genomic and chromosome stabilization genes in injured muscle.

Muscle injuries are the most prevalent type of injury in sports. A great number of athletes have relapsed in muscle injuries not being treated properly. Photobiomodulation therapy is an inexpensive and safe technique with many benefits in muscle injury treatment. However, little has been explored about the infrared laser effects on DNA and telomeres in muscle injuries. Thus, the aim of this study was to evaluate photobiomodulation effects on mRNA relative levels from genes related to telomere and genomic stabilization in injured muscle. Wistar male rats were randomly divided into six groups: control, laser 25 mW, laser 75 mW, injury, injury laser 25 mW, and injury laser 75 mW. Photobiomodulation was performed with 904 nm, 3 J/cm2 at 25 or 75 mW. Cryoinjury was induced by two applications of a metal probe cooled in liquid nitrogen directly on the tibialis anterior muscle. After euthanasia, skeletal muscle samples were withdrawn and total RNA extracted for evaluation of mRNA levels from genomic (ATM and p53) and chromosome stabilization (TRF1 and TRF2) genes by real-time quantitative polymerization chain reaction. Data show that photobiomodulation reduces the mRNA levels from ATM and p53, as well reduces mRNA levels from TRF1 and TRF2 at 25 and 75 mW in injured skeletal muscle. In conclusion, photobiomodulation alters mRNA relative levels from genes related to genomic and telomere stabilization in injured skeletal muscle.

Chromosomal evolution and phylogeny in the Nullicauda group (Chiroptera, Phyllostomidae): evidence from multidirectional chromosome painting.

BACKGROUND: The family Phyllostomidae (Chiroptera) shows wide morphological, molecular and cytogenetic variation; many disagreements regarding its phylogeny and taxonomy remains to be resolved. In this study, we use chromosome painting with whole chromosome probes from the Phyllostomidae Phyllostomus hastatus and Carollia brevicauda to determine the rearrangements among several genera of the Nullicauda group (subfamilies Gliphonycterinae, Carolliinae, Rhinophyllinae and Stenodermatinae). RESULTS: These data, when compared with previously published chromosome homology maps, allow the construction of a phylogeny comparable to those previously obtained by morphological and molecular analysis. Our phylogeny is largely in agreement with that proposed with molecular data, both on relationships between the subfamilies and among genera; it confirms, for instance, that Carollia and Rhinophylla, previously considered as part of the same subfamily are, in fact, distant genera. CONCLUSIONS: The occurrence of the karyotype considered ancestral for this family in several different branches suggests that the diversification of Phyllostomidae into many subfamilies has occurred in a short period of time. Finally, the comparison with published maps using human whole chromosome probes allows us to track some syntenic associations prior to the emergence of this family.

B Chromosome Diversity and Repetitive Sequence Distribution in an Isolated Population of Akodon montensis (Rodentia, Sigmodontinae).

B chromosomes are supernumerary chromosomes found in the karyotypes of approximately 15% of all eukaryotic species. They present parasitic behavior and do not follow the standard Mendelian pattern of inheritance, resulting in an imbalance in gametogenesis. The evolutionary dynamics of B chromosomes is still unknown for many species, but studies indicate that the accumulation of repetitive sequences plays an important role in the differentiation of these elements. We analyzed morphology, frequency, and possible homologies amongst different B chromosomes found in an isolated Akodon montensis population in southern Brazil. Repetitive sequences (18S, 5S rDNA and telomeric sequences) were used to test for their accumulation on the supernumerary chromosomes and describe their localization in the species. The results indicate 4 different B chromosome morphotypes, and DNA libraries were generated for 3 of them. 18S rDNA was labelled polymorphically, except in the B chromosomes, whereas the 5S rDNA was located exclusively in an interstitial position on the long arm of chromosome 5. Chromosome painting with the B probes based on FISH revealed a homologous composition for all B chromosome morphotypes and no homology with the chromosomes in the A complement. B chromosomes found in this population may have a common origin and subsequently diversified in size and morphology.

Chromosomal phylogeny of Vampyressine bats (Chiroptera, Phyllostomidae) with description of two new sex chromosome systems.

BACKGROUND: The subtribe Vampyressina (sensu Baker et al. 2003) encompasses approximately 43 species and seven genera and is a recent and diversified group of New World leaf-nosed bats specialized in fruit eating. The systematics of this group continues to be debated mainly because of the lack of congruence between topologies generated by molecular and morphological data. We analyzed seven species of all genera of vampyressine bats by multidirectional chromosome painting, using whole-chromosome-painting probes from Carollia brevicauda and Phyllostomus hastatus. Phylogenetic analyses were performed using shared discrete chromosomal segments as characters and the Phylogenetic Analysis Using Parsimony (PAUP) software package, using Desmodontinae as outgroup. We also used the Tree Analysis Using New Technology (TNT) software. RESULTS: The result showed a well-supported phylogeny congruent with molecular topologies regarding the sister taxa relationship of Vampyressa and Mesophylla genera, as well as the close relationship between the genus Chiroderma and Vampyriscus. CONCLUSIONS: Our results supported the hypothesis that all genera of this subtribe have compound sex chromosome systems that originated from an X-autosome translocation, an ancestral condition observed in the Stenodermatinae. Additional rearrangements occurred independently in the genus Vampyressa and Mesophylla yielding the X1X1X2X2/X1X2Y sex chromosome system. This work presents additional data supporting the hypothesis based on molecular studies regarding the polyphyly of the genus Vampyressa and its sister relationship to Mesophylla.

Genetic Diversity and Population Structure in South African, French and Argentinian Angora Goats from Genome-Wide SNP Data.

The Angora goat populations in Argentina (AR), France (FR) and South Africa (SA) have been kept geographically and genetically distinct. Due to country-specific selection and breeding strategies, there is a need to characterize the populations on a genetic level. In this study we analysed genetic variability of Angora goats from three distinct geographical regions using the standardized 50k Goat SNP Chip. A total of 104 goats (AR: 30; FR: 26; SA: 48) were genotyped. Heterozygosity values as well as inbreeding coefficients across all autosomes per population were calculated. Diversity, as measured by expected heterozygosity (HE) ranged from 0.371 in the SA population to 0.397 in the AR population. The SA goats were the only population with a positive average inbreeding coefficient value of 0.009. After merging the three datasets, standard QC and LD-pruning, 15 105 SNPs remained for further analyses. Principal component and clustering analyses were used to visualize individual relationships within and between populations. All SA Angora goats were separated from the others and formed a well-defined, unique cluster, while outliers were identified in the FR and AR breeds. Apparent admixture between the AR and FR populations was observed, while both these populations showed signs of having some common ancestry with the SA goats. LD averaged over adjacent loci within the three populations per chromosome were calculated. The highest LD values estimated across populations were observed in the shorter intervals across populations. The Ne for the Angora breed was estimated to be 149 animals ten generations ago indicating a declining trend. Results confirmed that geographic isolation and different selection strategies caused genetic distinctiveness between the populations.

Genetic evidence for chromosome 4 loci influencing learning and memory.

The Lewis (LEW) and SHR (Spontaneously Hypertensive Rats) inbred rat strains differ in several anxiety/emotionality and learning/memory-related behaviors. We aimed to search quantitative trait locus (QTL) that influence these behaviors and confirm their effects in a congenic rat strain SLA16 (SHR.LEW.Anxrr16). LEW females and SHR males were intercrossed to produce F2 rats (96/sex), which were all tested in the plus-maze discriminative avoidance task (PMDAT), open-field (OF), object recognition (OR), spontaneous alternation (SA) and fear conditioning (FC). All animals were genotyped for microsatellite markers located on chromosome (Chr) 4. Behavioral and genotypic data were used to perform factor and QTL analyses. Also, to confirm the QTL effects, we tested male and female SLA16 rats and their isogenic control SHR in the same behavioral tests. A factor analysis of the F2 population revealed a correlation between anxiety/emotionality related behaviors and learning/memory in both sexes. QTL analysis revealed two significant QTL in males and three in females, on behavioral parameters in the PMDAT, OF and FC. Four QTL found herein were confirmed in SLA16 rats. The SLA16 strain displayed lower levels of anxiety/emotionality, higher locomotor activity and deficits in learning/memory in comparison with SHR strain. The Chr 4 contains genes influencing anxiety/emotionality and learning/memory behaviors and the SLA16 strain represents a valuable tool in the search for them. The use of the SLA16 strain as a genetic model for studying behavioral phenomena and their implications for psychiatric disorders are discussed.

Contexto sociodemográfico de los homicidios en México D.F.: un análisis espacial / Sociodemographic context of homicide in Mexico City: a spatial analysis

OBJETIVO:Investigar el patrón de distribución espacial de la tasa de homicidios y su relación con las características sociodemográficas en las delegaciones de Benito Juárez, Coyoacán y Cuauhtémoc de la Ciudad de México en el año 2010. MÉTODOS: Estudio inferencial de corte transversal que usa métodos de análisis espacial para estudiar la asociación espacial de la tasa de homicidios y las características demográficas. La asociación espacial fue determinada a través del cociente de localización, análisis de regresión múltiple y el uso de la regresión geográficamente ponderada. RESULTADOS: Los homicidios muestran un patrón de localización heterogéneo con altas tasas en zonas con uso del suelo no residencial, con baja densidad de población y baja marginación. CONCLUSIONES: El uso de herramientas de análisis espacial son instrumentos poderosos para el diseño de políticas de seguridad pública preventiva y recreativa que busquen reducir la mortalidad por causas externas como homicidios.

OBJECTIVE:Investigate the spatial distribution pattern of the homicide rate and its relation to sociodemographic features in the Benito Juárez, Coyoacán, and Cuauhtémoc districts of Mexico City in 2010. METHODS: Inferential cross-sectional study that uses spatial analysis methods to study the spatial association of the homicide rate and demographic features. Spatial association was determined through the location quotient, multiple regression analysis, and the use of geographically weighted regression. RESULTS: Homicides show a heterogeneous location pattern with high rates in areas with non-residential land use, low population density, and low marginalization. CONCLUSIONS: Spatial analysis tools are powerful instruments for the design of prevention- and recreation-focused public safety policies that aim to reduce mortality from external causes such as homicides.

Study of lipid metabolism-related genes as candidate genes of sexual precocity in Nellore cattle.

The objective of this study was to identify associations between known polymorphisms in genes related to adipose tissue and sexual precocity in Nellore cattle. A total of 1689 precocious and non-precocious heifers belonging to farms participating in Conexão Delta G breeding program were studied. SNPs from the Illumina High-Density Bovine SNP BeadChip were used. This chip contains 777,000 SNPs located within the region of the candidate genes at a distance of up to 5 kb, considering that linkage disequilibrium (LD) exists at this distance. Linear models were used for statistical analysis. The fastPHASE and GenomeStudio programs were used for haplotype reconstruction and LD analysis based on r2 statistics. Fifty-seven candidate genes and 443 SNPs were analyzed: among the latter, 370 SNPs formed 83 haplotypes, while the remaining SNPs were studied separately. Statistical analysis showed that only three haplotypes, one haplotype consisting of two SNPs located in the FABP4 gene and two haplotypes consisting of four and two SNPs located in the PPP3CA gene, had a significant effect on sexual precocity at P < 0.05. It can be concluded that the FABP4 and PPP3CA genes influence sexual precocity and may therefore be used in selection programs designed to improve sexual precocity in Nellore cattle.