Rodent Diversity and Land Use in Montebello,Chiapas, Mexico

We analyzed the abundance and diversity of Heteromyid and Murid rodents in the Lagos de Montebello National Park and adjacent areas, Chiapas, Mexico. We sampled three habitat types with different degrees of disturbance: pine-oak-liquidambar forest, ecotone and crop farming lands. Habitat types were defined considering characteristics such as heterogeneity, structural complexity and arboreal cover. We obtained ancillary habitat data considered important for small mammal requirements. Data on rodent communities were obtained by capture-mark-recapture between February and October 1996. We made 410 captures in 3820 trap-nights effort. Ten species were recorded, including one endemic with restricted distribution in Chiapas. Mouse diversity in the forest was significantly higher than within the farm lands. A Kendall correlation analysis showed positive relationship between rodent community species richness and habitat heterogeneity. Diversity of rodents was associated with the habitat complexity and structural elements, and negatively correlated with farming intensity. We found a high beta diversity and low similarity of the rodent communities in the three different habitats. Community composition strongly changed from the forest through the ecotone into the farm lands, with five species gained and seven species lost. The highest species richness was found in the ecotone; however, it showed a strong dominance of a single species that can convert into a plague of crops, and relatively low abundance of the other species. The pine-oak-liquidambar forest had the highest diversity indices, sheltering a particular rodent community within the study area, it therefore probably has the most important role in the conservation of the local biodiversity.     

Citicoline (CDP‐choline) increases Sirtuin1 expression concomitant to neuroprotection in experimental stroke

CDP‐choline has shown neuroprotective effects in cerebral ischemia. In humans, although a recent trial International Citicoline Trial on Acute Stroke (ICTUS) has shown that global recovery is similar in CDP‐choline and placebo groups, CDP‐choline was shown to be more beneficial in some patients, such as those with moderate stroke severity and not treated with t‐PA. Several mechanisms have been proposed to explain the beneficial actions of CDP‐choline. We have now studied the participation of Sirtuin1 (SIRT1) in the neuroprotective actions of CDP‐choline. Fischer rats and Sirt1^?/? mice were subjected to permanent focal ischemia. CDP‐choline (0.2 or 2 g/kg), sirtinol (a SIRT1 inhibitor; 10 mg/kg), and resveratrol (a SIRT1 activator; 2.5 mg/kg) were administered intraperitoneally. Brains were removed 24 and 48 h after ischemia for western blot analysis and infarct volume determination. Treatment with CDP‐choline increased SIRT1 protein levels in brain concomitantly to neuroprotection. Treatment with sirtinol blocked the reduction in infarct volume caused by CDP‐choline, whereas resveratrol elicited a strong synergistic neuroprotective effect with CDP‐choline. CDP‐choline failed to reduce infarct volume in Sirt1^?/? mice. Our present results demonstrate a robust effect of CDP‐choline like SIRT1 activator by up‐regulating its expression. Our findings suggest that therapeutic strategies to activate SIRT1 may be useful in the treatment of stroke.

     

QTL mapping and confirmation for tolerance of anaerobic conditions during germination derived from the rice landrace Ma-Zhan Red

Wide adoption of direct-seeded rice practices has been hindered by poorly leveled fields, heavy rainfall and poor drainage, which cause accumulation of water in the fields shortly after sowing, leading to poor crop establishment. This is due to the inability of most rice varieties to germinate and reach the water surface under complete submergence. Hence, tolerance of anaerobic conditions during germination is an essential trait for direct-seeded rice cultivation in both rainfed and irrigated ecosystems. A QTL study was conducted to unravel the genetic basis of tolerance of anaerobic conditions during germination using a population derived from a cross between IR42, a susceptible variety, and Ma-Zhan Red, a tolerant landrace from China. Phenotypic data was collected based on the survival rates of the seedlings at 21 days after sowing of dry seeds under 10 cm of water. QTL analysis of the mapping population consisting of 175 F_2:3 families genotyped with 118 SSR markers identified six significant QTLs on chromosomes 2, 5, 6, and 7, and in all cases the tolerant alleles were contributed by Ma-Zhan Red. The largest QTL on chromosome 7, having a LOD score of 14.5 and an R ² of 31.7 %, was confirmed using a BC₂F₃ population. The QTLs detected in this study provide promising targets for further genetic characterization and for use in marker-assisted selection to rapidly develop varieties with improved tolerance to anaerobic condition during germination. Ultimately, this trait can be combined with other abiotic stress tolerance QTLs to provide resilient varieties for direct-seeded systems.     

Human talus bones from the Middle Pleistocene site of Sima de los Huesos (Sierra de Atapuerca,Burgos, Spain)

Here we present and describe comparatively 25 talus bones from the Middle Pleistocene site of the Sima de los Huesos (SH) (Sierra de Atapuerca, Burgos, Spain). These tali belong to 14 individuals (11 adult and three immature). Although variation among Middle and Late Pleistocene tali tends to be subtle, this study has identified unique morphological characteristics of the SH tali. They are vertically shorter than those of Late Pleistocene Homo sapiens, and show a shorter head and a broader lateral malleolar facet than all of the samples. Moreover, a few shared characters with Neanderthals are consistent with the hypothesis that the SH population and Neanderthals are sister groups. These shared characters are a broad lateral malleolar facet, a trochlear height intermediate between modern humans and Late Pleistocene H. sapiens, and a short middle calcaneal facet. It has been possible to propose sex assignment for the SH tali based on their size. Stature estimates based on these fossils give a mean stature of 174.4 cm for males and 161.9 cm for females, similar to that obtained based on the long bones from this same site.     

Rapid Divergent Evolution of Male Genitalia Among Populations of Drosophila buzzatii

Increasing evidence from multiple animal systems suggests that genital evolution and diversification are driven by rapid and strong evolutionary forces. Particularly, the morphology of male genital structures is considered to be among the fastest evolving traits in animal groups with internal fertilization. In this study, we investigated patterns of male genital variation within and between natural populations of the cactophilic fly Drosophila buzzatii in its original geographic distribution range in the Neotropics. We detected significant morphological differences among populations and distinguished five differentiated groups. Moreover, among population differentiation in genital morphology was associated with the degree of geographic isolation among populations and clearly contrasted with the general homogeneity detected for the putatively neutral mitochondrial gene COI. Integrating our present data with previous molecular population genetic surveys, our results suggest that male genital morphology has rapidly diverged after the recent demographic expansion that D. buzzatii has undergone in the arid zones of South America. Because the “lock and key” hypothesis failed to explain the present pattern, we explored alternative explanations for the observed pattern of genital diversification including drift-facilitated sexual selection.     

Production of 10(S)-hydroxy-8(E)-octadecenoic and 7,10(S,S)-hydroxy-8(E)-octadecenoic ethyl esters by Novozym 435 in solvent-free media

Novozym 435, lipase B from Candida antarctica, was used in this study for the production of ethyl esters. For the first time, trans-hydroxy-fatty acid ethyl esters were synthesized in vitro in solvent-free media. We studied the effects of the substrate–ethanol molar ratio and enzyme synthetic stability of the biocatalyst. To determine the structure of the formed compounds, Fourier transformed infrared spectroscopy, nuclear magnetic resonance, and matrix-assisted laser desorption/ionization–time-of-flight mass spectrometry were used, three less time-consuming structural techniques. trans-Hydroxy-fatty acid ethyl esters were synthesized with a reaction yield of 90 % or higher with optimal reaction conditions.     

Population genetics structure of glyphosate‐resistant Johnsongrass (Sorghum halepense L. Pers) does not support a single origin of the resistance

Single sequence repeats (SSR) developed for Sorghum bicolor were used to characterize the genetic distance of 46 different Sorghum halepense (Johnsongrass) accessions from Argentina some of which have evolved toward glyphosate resistance. Since Johnsongrass is an allotetraploid and only one subgenome is homologous to cultivated sorghum, some SSR loci amplified up to two alleles while others (presumably more conserved loci) amplified up to four alleles. Twelve SSR providing information of 24 loci representative of Johnsongrass genome were selected for genetic distance characterization. All of them were highly polymorphic, which was evidenced by the number of different alleles found in the samples studied, in some of them up to 20. UPGMA and Mantel analysis showed that Johnsongrass glyphosate‐resistant accessions that belong to different geographic regions do not share similar genetic backgrounds. In contrast, they show closer similarity to their neighboring susceptible counterparts. Discriminant Analysis of Principal Components using the clusters identified by K‐means support the lack of a clear pattern of association among samples and resistance status or province of origin. Consequently, these results do not support a single genetic origin of glyphosate resistance. Nucleotide sequencing of the 5‐enolpyruvylshikimate‐3‐phosphate synthase (EPSPS) encoding gene from glyphosate‐resistant and susceptible accessions collected from different geographic origins showed that none presented expected mutations in aminoacid positions 101 and 106 which are diagnostic of target‐site resistance mechanism.