Who is coordinating collective movements in black and gold howler monkeys?

Decisions about when and where to travel are likely to have a strong influence on the feeding, ecology, and foraging strategies of individual primates living in a cohesive social group. Specifically, given differences in age, sex, reproductive status, or social dominance, particular group members may benefit from remaining at their present location while others may benefit from traveling to another area of their range to feed or rest. In this study, we present data on movement coordination in two groups of wild black and gold howler monkeys inhabiting Isla Brasilera (27º 20′S and 58º 40′W) in northern Argentina. We examine how factors such as sex, age, reproductive status, and dominance affect patterns of group movement coordination at feeding or resting sites, and in the context of intergroup encounters. Two groups were followed five days a month from sunrise to sunset during June to November 2004. Using focal and scan sampling techniques, we recorded 262 group displacements, the identity of the individual initiating and leading displacement, and the identity of the first individual to arrive at feeding, resting, or intergroup encounter sites. We found that overall age was the only factor that influenced group coordination: adults led more often (94.5 %) than immature individuals (5.5 %) in both groups. We did not find differences among adults. However, we found that males lead more often than females at intergroup encounters, consistent with the male-mate defense hypothesis. The distributed leadership pattern among adults observed in this study may suggest that adult individuals make equally shared consensus decisions. This pattern should be further examined using this individual-level approach in other populations of black and gold howlers, other species of howlers, and in other atelines in which within-group social tolerance is the rule rather than the exception.     

Molecular profile of the NF‐κB signalling pathway in human colorectal cancer

The development and progression of colorectal cancer (CRC) have been associated with inflammation processes that involve the overactivation of the NF‐κB signalling pathway. The characterization of the NF‐κB expression profile in CRC is an important topic since the suppression of NF‐κB represents a potential therapeutic approach. In this study, we assessed the expression levels of 84 NF‐κB‐related genes in paired tumoral (T) and peritumoral (PT) tissues from 18 CRC patients and 18 normal colonic mucosae, and the expression levels of three miRNAs targeting the most dysregulated genes revealed by the case–control analysis. Comparing the gene expression profile of T and controls, 60 genes were dysregulated. The comparison of T and PT revealed 17 dysregulated genes in the tumoral tissues, with IL1B, CXCL8, IL1A, and CSF2 being the most upregulated. Notably, through a bioinformatics analysis, the differential gene expression of 11 out of the 17 genes was validated on a larger cohort of 308 CRC patients compared with 41 controls. Moreover, a decrease in the levels of RELA, NOD1, CASP8, BCL2L1, ELK1, and IKBKB was identified in poorly differentiated tumours compared to moderately differentiated tumours. The analysis of the three miRNAs targeting IL1B, CXCL8, IL1A, and CSF2 showed that miR‐182‐5p was upregulated in T compared with PT, whereas miR‐10b‐5p was downregulated in T compared with PT and control tissues. Our results may contribute to the design of new experimental therapeutic strategies based on endogenous molecules, such as miRNAs, to target the genetic key players of the NF‐ κB pathway.     

The Mitochondrial Intermembrane Space Oxireductase Mia40 Funnels the Oxidative Folding Pathway of the Cytochrome c Oxidase Assembly Protein Cox19

Mia40-catalyzed disulfide formation drives the import of many proteins into the mitochondria. Here we characterize the oxidative folding of Cox19, a twin CX₉C Mia40 substrate. Cox19 oxidation is extremely slow, explaining the persistence of import-competent reduced species in the cytosol. Mia40 accelerates Cox19 folding through the specific recognition of the third Cys in the second helical CX₉C motif and the subsequent oxidation of the inner disulfide bond. This renders a native-like intermediate that oxidizes in a slow uncatalyzed reaction into native Cox19. The same intermediate dominates the pathway in the absence of Mia40, and chemical induction of an α-helical structure by trifluoroethanol suffices to accelerate productive folding and mimic the Mia40 folding template mechanism. The Mia40 role is to funnel a rough folding landscape, skipping the accumulation of kinetic traps, providing a rationale for the promiscuity of Mia40.     

Sex determination and optimal development in the Moorish gecko,Tarentola mauritanica

Under temperature sex determination (TSD), sex is determined by temperature during embryonic development. Depending on ecological and physiological traits and plasticity, TSD species may face demographic collapse due to climate change. In this context, asymmetry in bilateral organisms can be used as a proxy for developmental instability and, therefore, deviations from optimal incubation conditions. Using Tarentola mauritanica gecko as a model, this study aimed first to confirm TSD, its pattern and pivotal temperature, and second to assess the local adaptation of TSD and variation of asymmetry patterns across four populations under different thermal regimes. Eggs were incubated at different temperatures, and hatchlings were sexed and measured. The number of lamellae was counted in adults and hatchlings. Results were compatible with a TSD pattern with males generated at low and females at high incubation temperatures. Estimated pivotal temperature coincided with the temperature producing lower embryonic mortality, evidencing selection towards balanced sex ratios. The temperature of oviposition was conservatively selected by gravid females. Asymmetry patterns found were likely related to nest temperature fluctuations. Overall, the rigidity of TSD may compromise reproductive success, and demographic stability in this species in case thermal nest choice becomes constrained by climate change.     

Climatic stability in the Brazilian Cerrado: implications for biogeographical connections of South American savannas,species richness and conservation in a biodiversity hotspot

Aim To investigate the historical distribution of the Cerrado across Quaternary climatic fluctuations and to generate historical stability maps to test: (1) whether the ‘historical climate’ stability hypothesis explains squamate reptile richness in the Cerrado; and (2) the hypothesis of Pleistocene connections between savannas located north and south of Amazonia. Location The Cerrado, a savanna biome and a global biodiversity hotspot distributed mainly in central Brazil. Methods We generated occurrence datasets from 1000 presence points randomly selected from the entire distribution of the Cerrado, as determined by two spatial definitions. We modelled the potential Cerrado distribution by implementing a maximum‐entropy machine‐learning algorithm across four time projections: current, mid‐Holocene (6 ka), Last Glacial Maximum (LGM, 21 ka) and Last Interglacial (LIG, 120 ka). We generated historical stability maps (refugial areas) by overlapping presence/absence projections of all scenarios, and checked consistencies with qualitative comparisons with available fossil pollen records. We built a spatially explicit simultaneous autoregressive model to explore the relationship between current climate, climatic stability, and squamate species richness. Results Models predicted the LGM and LIG as the periods of narrowest and widest Cerrado distributions, respectively, and were largely corroborated by palynological evidence. We found evidence for two savanna corridors (eastern coastal during the LIG, and Andean during the LGM) and predicted a large refugial area in the north‐eastern Cerrado (Serra Geral de Goiás refugium). Variables related to climatic stability predicted squamate richness better than present climatic variables did. Main conclusions Our results indicate that Bolivian savannas should be included within the Cerrado range and that the Cerrado’s biogeographical counterparts are not Chaco and Caatinga but rather the disjunct savannas of the Guyana shield plateaus. Climatic stability is a good predictor of Cerrado squamate richness, and our stability maps could be used in future studies to test diversity patterns and genetic signatures of different taxonomic groups and as a higher‐order landscape biodiversity surrogate for conservation planning.     

Satellite-DNA evolutionary patterns under a complex evolutionary scenario: the case of Acrolophus subgroup (Centaurea L., Compositae) from the western Mediterranean

Within the genus Centaurea (subtribe Centaureinae, tribe Cardueae, Compositae) hybridizations and reticulate-evolution phenomena have widely been recognized. This is especially true in the taxa included in the subgroup Acrolophus from the western Mediterranean area, in which recurrent hybridizations of parapatric ("microallopatric") lineages within the geographical range of a primary radiation have been suggested. The subgroup Acrolophus includes taxa from three sections (i.e. Acrolophus, Phalolepis and Willkommia), and, together with other subgroups, forms the named Jacea group (one of the three main groups into which Centaurea is divided). In this paper, we have studied the influence that the complex evolutionary scenario described for the Acrolophus subgroup from the western Mediterranean exerts on the evolutionary pattern of a satellite-DNA family, the HinfI family, which exists within the genomes of these taxa. To this end, we have analyzed the evolution of this satellite-DNA family in taxa from different taxonomic comparative levels: i) seven subspecies of the C. boissieri complex (one of which with two varieties) of the sect. Willkommia; ii) species of the sections Willkommia (10 species, 19 taxa), Acrolophus (two species), and Phalolepis (two species), all in the Acrolophus subgroup; iii) one external species to the Jacea group, C. granatensis from the group Acrocentron; iv) and species from other related genera from the Centaureinae subtribe (Phonus and Carthamus, both belonging to the Carthamus group). The influence of the suggested model for the origin and diversification of the Acrolophus subgroup is evidenced by the existence of three different HinfI satellite-DNA subfamilies coexisting in some genomes, and by the analysis that we have made by comparing site-by-site the transition stages in the process of concerted evolution between the sequences of the each subfamily. From this analysis, we can deduce that the HinfI repeated subfamilies evolved in a gradual manner, and that the different stages of concerted evolution fit quite well with the combined nuclear-chloroplast-DNA-deduced divergences and phylogeny of the subtribe Centaureinae. The HinfI satellite-DNA from the Carthamus species group (genera Carthamus and Phonus) and from the Acrocentron group (Centaurea granatensis) shows a high intraspecific conservation of the repeats, suggesting that the mechanisms producing concerted evolution have been efficient in these taxa. In addition, the comparison of individual nucleotide positions between related species shows a paucity in the spreading of variants in each subfamily with satellite-DNA divergence, an indication of a constant rate of homogenization of the repeated cluster. On the contrary, this trend is absent in the comparisons of the HinfI sequences from taxa of the subgroup Acrolophus. In this subgroup, we have found in this repetitive family similar representative average sequences for each taxon analyzed, polymorphic sites in each taxon being scant, most of them autapomorphic, representing early stages of genetic differentiation between taxa in the process of concerted evolution. The absence of concerted evolution was visualized by similar levels of intraspecific variation and interspecific divergence and by the lack of fixed species-diagnostic nucleotide sites. These facts might reflect the reticulate mode of evolution of Acrolophus.     

RNA secondary structure mediates alternative 3'ss selection in Saccharomyces cerevisiae

Alternative splicing is the mechanism by which different combinations of exons in the pre-mRNA give rise to distinct mature mRNAs. This process is mediated by splicing factors that bind the pre-mRNA and affect the recognition of its splicing signals. Saccharomyces species lack many of the regulatory factors present in metazoans. Accordingly, it is generally assumed that the amount of alternative splicing is limited. However, there is recent compelling evidence that yeast have functional alternative splicing, mainly in response to environmental conditions. We have previously shown that sequence and structure properties of the pre-mRNA could explain the selection of 3' splice sites (ss) in Saccharomyces cerevisiae. In this work, we extend our previous observations to build a computational classifier that explains most of the annotated 3'ss in the CDS and 5' UTR of this organism. Moreover, we show that the same rules can explain the selection of alternative 3'ss. Experimental validation of a number of predicted alternative 3'ss shows that their usage is low compared to annotated 3'ss. The majority of these alternative 3'ss introduce premature termination codons (PTCs), suggesting a role in expression regulation. Furthermore, a genome-wide analysis of the effect of temperature, followed by experimental validation, yields only a small number of changes, indicating that this type of regulation is not widespread. Our results are consistent with the presence of alternative 3'ss selection in yeast mediated by the pre-mRNA structure, which can be responsive to external cues, like temperature, and is possibly related to the control of gene expression.     

Characterization of bimodal cell death of insect cells in a rotating‐wall vessel and shaker flask

In previous publications, we reported the benefits of a high‐aspect rotating‐wall vessel (HARV) over conventional bioreactors for insect‐cell cultivation in terms of reduced medium requirements and enhanced longevity. To more fully understand the effects that HARV cultivation has on longevity, the present study characterizes the mode and kinetics of Spodoptera frugiperda cell death in this quiescent environment relative to a shaker‐flask control. Data from flow cytometry and fluorescence microscopy show a greater accumulation of apoptotic cells in the HARV culture, by a factor of at least 2 at the end of the cultivation period. We present a kinetic model of growth and bimodal cell death. The model is unique for including both apoptosis and necrosis, and further, transition steps within the two pathways. Kinetic constants reveal that total cell death is reduced in the HARV and the accumulation of apoptotic cells in this vessel results from reduced depletion by lysis and secondary necrosis. The ratio of early apoptotic to necrotic cell formation is found independent of cultivation conditions. In the model, apoptosis is only well represented by an integral term, which may indicate its dependence on accumulation of some factor over time; in contrast, necrosis is adequately represented with a first‐order term. Cell‐cycle analysis shows the percent of tetraploid cells gradually decreases during cultivation in both vessels. For example, between 90% and 70% viability, tetraploid cells in the HARV drop from 43 ± 1% to 24 ± 4%. The data suggests the tetraploid phase as the likely origin for apoptosis in our cultures. Possible mechanisms for these changes in bimodal cell death are discussed, including hydrodynamic forces, cell–cell interactions, waste accumulation, and mass transport. These studies may benefit insect‐cell cultivation by increasing our understanding of cell death in culture and providing a means for further enhancing culture longevity. © 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 64: 14–26, 1999.