Vibrios of the spotted rose snapper Lutjanus guttatus Steindachner, 1869 from northwestern Mexico

AIM: To characterize and identify vibrios present in wild and cultured juvenile snappers (Lutjanus guttatus) in northwestern Mexico. METHODS AND RESULTS: Spotted rose snapper juveniles were collected at four localities in northwestern Mexico. Bacteria were isolated from external lesions, kidney, liver, and spleen from cultured and wild caught organisms. In total, 280 isolates were obtained and fingerprinted with rep-PCR (GTG5). Nearly 93.2% of the strains belonged to the Vibrionaceae family. Species and genera identified were Photobacterium damselae subsp. damselae (76 strains), Photobacterium leiognathi (13), Vibrio sp. (24), Vibrio alginolyticus (12), Vibrio campbellii (19), Vibrio fortis (9), Vibrio harveyi (49), Vibrio ichthyoenteri (4), Vibrio mediterranei (4), Vibrio parahaemolyticus (1), Vibrio ponticus (2), Vibrio rotiferianus (22), and four potential new species. Conclusions: A wide diversity of vibrios was found in the external lesions and internal organs of both wild and cultured spotted rose snapper juveniles. In total, 12 species of vibrios and four potential new species were identified. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study on the vibrios present in the spotted rose snapper and therefore might serve as a basis for future studies and diagnosis.     

The P34G mutation reduces the transforming activity of K-Ras and N-Ras in NIH 3T3 cells but not of H-Ras

Ras proteins (H-, N-, and K-Ras) operate as molecular switches in signal transduction cascades controlling cell proliferation, differentiation, or apoptosis. The interaction of Ras with its effectors is mediated by the effector-binding loop, but different data about Ras location to plasma membrane subdomains and new roles for some docking/scaffold proteins point to signaling specificities of the different Ras proteins. To investigate the molecular mechanisms for these specificities, we compared an effector loop mutation (P34G) of three Ras isoforms (H-, N-, and K-Ras4B) for their biological and biochemical properties. Although this mutation diminished the capacity of Ras proteins to activate the Raf/ERK and the phosphatidylinositol 3-kinase/AKT pathways, the H-Ras V12G34 mutant retained the ability to cause morphological transformation of NIH 3T3 fibroblasts, whereas both the N-Ras V12G34 and the K-Ras4B V12G34 mutants were defective in this biological activity. On the other hand, although both the N-Ras V12G34 and the K-Ras4B V12G34 mutants failed to promote activation of the Ral-GDS/Ral A/PLD and the Ras/Rac pathways, the H-Ras V12G34 mutant retained the ability to activate these signaling pathways. Interestingly, the P34G mutation reduced specifically the N-Ras and K-Ras4B in vitro binding affinity to Ral-GDS, but not in the case of H-Ras. Thus, independently of Ras location to membrane subdomains, there are marked differences among Ras proteins in the sensitivity to an identical mutation (P34G) affecting the highly conserved effector-binding loop.     

Les Néandertaliens d’El Sidrón (Asturies,Espagne). Actualisation d’un nouvel échantillon

This paper synthesizes and updates the information coming from the El Sidrón (Asturias, Northern Spain) neandertal site. Since 2000, a new sample of Homo neanderthalensis dated to at least 49,000 years old is being systematically recovered at the El Sidrón cave site. The bone assemblage is located in a secondary position, and certainly derives from a close location. The sample is almost exclusively composed of human remains. There is a moderate number of Middle Paleolithic stone tools (n ≈ 415) and very few macro-faunal remains. All skeletal parts are preserved, including some rare bones such as the hyoid bone. Teeth are abundant (n = 213), cranial and postcranial remains are also well represented, but fragmentary, with a special presence of foot and hand bones. A minimum number of thirteen individuals has been identified, comprising different developmental stages from infancy to adulthood: one infant, two juveniles, three adolescents, and seven adults. Paleobiology of the El Sidrón humans fits the pattern found in other neandertal samples: a high incidence of dental hypoplasia and interproximal grooves, yet no serious traumatic lesions are present. Moreover, unambiguous evidence of human-induced modifications (cannibalism) was found on the human remains: cut marks, percussion pitting, conchoidal scars and adhering flakes. Individuals seem to have been treated differentially. Morphologically, the El Sidrón humans show a large number of neandertal lineage-derived features even though certain traits place the sample at the limits of neandertal variation. Integrating the El Sidrón human mandibles and occipital bones into the larger neandertal sample reveals a possible geographic patterning, with southern Neandertals showing broader faces with increased lower facial heights. Ancient DNA analyses have been carried out, developing an anti-contamination protocol of excavation for minimizing the risk of modern human DNA contamination. As a result both mitochondrial and nuclear DNA have been extracted from dental and osteological remains. Curiously, mtDNA comparative analyses suggest a population affinity of Iberian Peninsula Neandertals with Central European Neandertals. Nuclear DNA analyses have permitted the identification of some functional genes such as the melanocortin 1 receptor (MC1R), which regulates hair and skin pigmentation; the FOXP2, a gene involved in the development of language; and the gene involved in the ABO blood group system. Nowadays the large El Sidrón sample is the most significant neandertal sample from the Iberian Peninsula, and augments the European evolutionary lineage fossil record, supporting ecogeographical variability across neandertal populations.     

Lymphocyte proliferation kinetics and genotoxic findings in a pilot study on individuals chronically exposed to arsenic in Mexico

In the search for early biological markers to detect genetic damage, a pilot study on a hydroarsenicism-exposed group was designed. Blood and urine samples were taken from 11 individuals chronically exposed and from 13 individuals with lower exposure to the metal. Lymphocyte cultures for cytogenetic studies and HGPRT assay were done with coded peripheral blood samples, while arsenic levels and the “rec assay” in B. subtilis were determined in urine samples. The highly exposed group excreted greater amounts of As, nevertheless the rec assay showed negative results. An interesting finding is that the cell-cycle kinetics exhibited a significant difference between the groups studied, the average generation time (AGT) was longer in the highly exposed group. The percentages of chromosomal aberrations and the frequencies of sister-chromatid exchanges were similar in both populations, although complex aberrations were more frequent in the highly exposed group, which also showed a higher average variation frequency in the HGPRT assay, but the 2 latter observations were not statistically significant. The lag in lymphocyte proliferation could mean an impairment of the immune response due to arsenic exposure.     

Bone remodelling in Neanderthal mandibles from the El Sidrón site (Asturias, Spain)

Skull morphology results from the bone remodelling mechanism that underlies the specific bone growth dynamics. Histological study of the bone surface from Neanderthal mandible specimens of El Sidrón (Spain) provides information about the distribution of the remodelling fields (bone remodelling patterns or BRP) indicative of the bone growth directions. In comparison with other primate species, BRP shows that Neanderthal mandibles from the El Sidrón (Spain) sample present a specific BRP. The interpretation of this map allows inferences concerning the growth directions that explain specific morphological traits of the Neanderthal mandible, such as its quadrangular shape and the posterior location of the mental foramen.     

Grb2 is a negative modulator of the intrinsic Ras-GEF activity of hSos1

hSos1 is a Ras guanine-nucleotide exchange factor. It was suggested that the carboxyl-terminal region of hSos1 down-regulates hSos1 functionality and that the intrinsic guanine-nucleotide exchange activity of this protein may be different before and after stimulation of tyrosine kinase receptors. Using different myristoylated hSos1 full-length and carboxyl-terminal truncated mutants, we show that Grb2 function accounts not only for recruitment of hSos1 to the plasma membrane but also for modulation of hSos1 activity. Our results demonstrate that the first two canonical Grb2 binding sites, inside the carboxyl-terminal region of hSos1, are responsible for this regulation. Following different approaches, such as displacement of Grb2 from the hSos1-Grb2 complex or depletion of Grb2 levels by small interfering RNA, we found that the full-length Grb2 proteins mediate negative regulation of the intrinsic Ras guanine-nucleotide exchange activity of hSos1.