Seasonal and Geographic Variation of Southern Blue Whale Subspecies in the Indian Ocean

Understanding the seasonal movements and distribution patterns of migratory species over ocean basin scales is vital for appropriate conservation and management measures. However, assessing populations over remote regions is challenging, particularly if they are rare. Blue whales (Balaenoptera musculus spp) are an endangered species found in the Southern and Indian Oceans. Here two recognized subspecies of blue whales and, based on passive acoustic monitoring, four “acoustic populations” occur. Three of these are pygmy blue whale (B.m. brevicauda) populations while the fourth is the Antarctic blue whale (B.m. intermedia). Past whaling catches have dramatically reduced their numbers but recent acoustic recordings show that these oceans are still important habitat for blue whales. Presently little is known about the seasonal movements and degree of overlap of these four populations, particularly in the central Indian Ocean. We examined the geographic and seasonal occurrence of different blue whale acoustic populations using one year of passive acoustic recording from three sites located at different latitudes in the Indian Ocean. The vocalizations of the different blue whale subspecies and acoustic populations were recorded seasonally in different regions. For some call types and locations, there was spatial and temporal overlap, particularly between Antarctic and different pygmy blue whale acoustic populations. Except on the southernmost hydrophone, all three pygmy blue whale acoustic populations were found at different sites or during different seasons, which further suggests that these populations are generally geographically distinct. This unusual blue whale diversity in sub-Antarctic and sub-tropical waters indicates the importance of the area for blue whales in these former whaling grounds.     

Key Features of Intertidal Food Webs That Support Migratory Shorebirds

The migratory shorebirds of the East Atlantic flyway land in huge numbers during a migratory stopover or wintering on the French Atlantic coast. The Brouage bare mudflat (Marennes-Oléron Bay, NE Atlantic) is one of the major stopover sites in France. The particular structure and function of a food web affects the efficiency of carbon transfer. The structure and functioning of the Brouage food web is crucial for the conservation of species landing within this area because it provides sufficient food, which allows shorebirds to reach the north of Europe where they nest. The aim of this study was to describe and understand which food web characteristics support nutritional needs of birds. Two food-web models were constructed, based on in situ measurements that were made in February 2008 (the presence of birds) and July 2008 (absence of birds). To complete the models, allometric relationships and additional data from the literature were used. The missing flow values of the food web models were estimated by Monte Carlo Markov Chain – Linear Inverse Modelling. The flow solutions obtained were used to calculate the ecological network analysis indices, which estimate the emergent properties of the functioning of a food-web.The total activities of the Brouage ecosystem in February and July are significantly different. The specialisation of the trophic links within the ecosystem does not appear to differ between the two models. In spite of a large export of carbon from the primary producer and detritus in winter, the higher recycling leads to a similar retention of carbon for the two seasons. It can be concluded that in February, the higher activity of the ecosystem coupled with a higher cycling and a mean internal organization, ensure the sufficient feeding of the migratory shorebirds.     

Structural,energetic, and dynamic responses of the native state ensemble of staphylococcal nuclease to cavity‐creating mutations

The effects of cavity‐creating mutations on the structural flexibility, local and global stability, and dynamics of the folded state of staphylococcal nuclease (SNase) were examined with NMR spectroscopy, MD simulations, H/D exchange, and pressure perturbation. Effects on global thermodynamic stability correlated well with the number of heavy atoms in the vicinity of the mutated residue. Variants with substitutions in the C‐terminal domain and the interface between α and β subdomains showed large amide chemical shift variations relative to the parent protein, moderate, widespread, and compensatory perturbations of the H/D protection factors and increased local dynamics on a nanosecond time scale. The pressure sensitivity of the folded states of these variants was similar to that of the parent protein. Such observations point to the capacity of the folded proteins to adjust to packing defects in these regions. In contrast, cavity creation in the β‐barrel subdomain led to minimal perturbation of the structure of the folded state, However, significant pressure dependence of the native state amide resonances, along with strong effects on native state H/D exchange are consistent with increased probability of population of excited state(s) for these variants. Such contrasted responses to the creation of cavities could not be anticipated from global thermodynamic stability or crystal structures; they depend on the local structural and energetic context of the substitutions. © 2012 Wiley Periodicals, Inc.     

Managing Insect Resistance to Plants Producing Bacillus thuringiensis Toxins

ABSTRACT:?

Insect-resistant transgenic plants have become an important tool for the protection of crops against insect pests. The acreage of insecticidal transgenic plants is expected to increase significantly in the near future. The bacterium Bacillus thuringiensis is currently the source of insecticidal proteins in commercial insect-resistant transgenic plants and will remain the most important source during the next decade. Insect resistance to B. thuringiensis Cry toxins is the main problem. Only one species, the diamondback moth, has evolved a resistance to B. thuringiensis-based formulations under field conditions. However, many other insect species were selected for resistance under laboratory conditions, indicating that there is a potential for evolution of resistance in most major pests. Many studies were conducted to elucidate the mode of action of the Cry toxins, the mechanisms and genetics of resistance, and the various factors influencing its development. This article reviews insect resistance to B. thuringiensis insecticidal proteins and related aspects, including the development of insect-resistant transgenic plants, B. thuringiensis toxins, their mode of action, mechanisms, stability, and genetics of resistance and management strategies for delaying resistance.     

Influence of microalgae cell wall characteristics on protein extractability and determination of nitrogen-to-protein conversion factors

Additional evidence about the influence of the cell wall physical and chemical characteristics on protein extractability was determined by calculating the conversion factors of five different microalgae known to have different cell wall composition, and their protein extracts. The conversion factors obtained for crude rigid cell walled Chlorella vulgaris, Nannochloropsis oculata and Haematococcus pluvialis were 6.35, 6.28 and 6.25, respectively, but for their protein extracts the values were lower with 5.96, 5.86 and 5.63. On the other hand, conversion factor obtained for fragile cell walled microalgae Porphyridium cruentum and Athrospira platensis was 6.35 for the former and 6.27 for the latter, with no significant difference for their protein extract with 6.34 for the former and 6.21 for the latter. In addition, the highest hydro-soluble protein percentage recovered from total protein was for P. cruentum 80.3 % and A. platensis 69.5 % but lower for C. vulgaris with 43.3 %, N. oculata with 33.3 % and H. pluvialis with 27.5 %. The study spotted the light on the influence of the cell wall on evaluating the conversion factor and protein extractability. In addition, it showed the necessity of finding the conversion factor every time accurate protein quantification is required, and proved that there is not a universal conversion factor that can be recommended.     

Evaluation of the protein quality of Porphyridium cruentum

The amino acid profile of the red microalga Porphyridium cruentum and its protein extract have been determined in order to assess the nutritional quality of this biomass for human consumption. Total protein determined by elemental analysis represented 56 % of its dry weight. Hydro-soluble proteins extracted at pH 12 and 40 °C were analysed by the Lowry method giving 47 %, which represented 84 % of total protein per dry weight. The amino acid sequence of the biomass and the protein extract was composed of a set of essential (39 % for the former and 37 % for the latter) and non-essential amino acids (61 % for the former and 63 % for the latter) that compares favourably with the standard protein/amino acid requirements proposed by Food and Agricultural Organisation and World Health Organisation.     

A Shared Neural Substrate for Mentalizing and the Affective Component of Sentence Comprehension

Using event-related fMRI in a sample of 42 healthy participants, we compared the cerebral activity maps obtained when classifying spoken sentences based on the mental content of the main character (belief, deception or empathy) or on the emotional tonality of the sentence (happiness, anger or sadness). To control for the effects of different syntactic constructions (such as embedded clauses in belief sentences), we subtracted from each map the BOLD activations obtained during plausibility judgments on structurally matching sentences, devoid of emotions or ToM. The obtained theory of mind (ToM) and emotional speech comprehension networks overlapped in the bilateral temporo-parietal junction, posterior cingulate cortex, right anterior temporal lobe, dorsomedial prefrontal cortex and in the left inferior frontal sulcus. These regions form a ToM network, which contributes to the emotional component of spoken sentence comprehension. Compared with the ToM task, in which the sentences were enounced on a neutral tone, the emotional sentence classification task, in which the sentences were play-acted, was associated with a greater activity in the bilateral superior temporal sulcus, in line with the presence of emotional prosody. Besides, the ventromedial prefrontal cortex was more active during emotional than ToM sentence processing. This region may link mental state representations with verbal and prosodic emotional cues. Compared with emotional sentence classification, ToM was associated with greater activity in the caudate nucleus, paracingulate cortex, and superior frontal and parietal regions, in line with behavioral data showing that ToM sentence comprehension was a more demanding task.     

A structural and functional analysis of the glycosyltransferase BshA from Staphylococcus aureus: Insights into the reaction mechanism and regulation of bacillithiol production

Bacillithiol is a glucosamine‐derived antioxidant found in several pathogenic Gram‐positive bacteria. The compound is involved in maintaining the appropriate redox state within the cell as well as detoxifying foreign agents like the antibiotic fosfomycin. Bacillithiol is produced via the action of three enzymes, including BshA, a retaining GT‐B glycosyltransferase that utilizes UDP‐N‐acetylglucosamine and l ‐malate to produce N‐acetylglucosaminyl‐malate. Recent studies suggest that retaining GT‐B glycosyltransferases like BshA utilize a substrate‐assisted mechanism that goes through an S_Ni‐like transition state. In a previous study, we relied on X‐ray crystallography as well as computational simulations to hypothesize the manner in which substrates would bind the enzyme, but several questions about substrate binding and the role of one of the amino acid residues persisted. Another study demonstrated that BshA might be subject to feedback inhibition by bacillithiol, but this phenomenon was not analyzed further to determine the exact mechanism of inhibition. Here we present X‐ray crystallographic structures and steady‐state kinetics results that help elucidate both of these issues. Our ligand‐bound crystal structures demonstrate that the active site provides an appropriate steric and geometric arrangement of ligands to facilitate the substrate‐assisted mechanism. Finally, we show that bacillithiol is competitive for UDP‐N‐acetylglucosamine with a K_i value near 120–130 μM and likely binds within the BshA active site, suggesting that bacillithiol modulates BshA activity via feedback inhibition. The work presented here furthers our understanding of bacillithiol metabolism and can aid in the development of inhibitors to counteract resistance to antibiotics such as fosfomycin.     

Predicting and testing physical locations of genetically mapped loci on tomato pachytene chromosome 1

Predicting the chromosomal location of mapped markers has been difficult because linkage maps do not reveal differences in crossover frequencies along the physical structure of chromosomes. Here we combine a physical crossover map based on the distribution of recombination nodules (RNs) on Solanum lycopersicum (tomato) synaptonemal complex 1 with a molecular genetic linkage map from the interspecific hybrid S. lycopersicum x S. pennellii to predict the physical locations of 17 mapped loci on tomato pachytene chromosome 1. Except for one marker located in heterochromatin, the predicted locations agree well with the observed locations determined by fluorescence in situ hybridization. One advantage of this approach is that once the RN distribution has been determined, the chromosomal location of any mapped locus (current or future) can be predicted with a high level of confidence.     

Brain responses to violet, blue, and green monochromatic light exposures in humans: prominent role of blue light and the brainstem

Background

Relatively long duration retinal light exposure elicits nonvisual responses in humans, including modulation of alertness and cognition. These responses are thought to be mediated in part by melanopsin-expressing retinal ganglion cells which are more sensitive to blue light than violet or green light. The contribution of the melanopsin system and the brain mechanisms involved in the establishment of such responses to light remain to be established.

Methodology/Principal Findings

We exposed 15 participants to short duration (50 s) monochromatic violet (430 nm), blue (473 nm), and green (527 nm) light exposures of equal photon flux (10¹³ph/cm²/s) while they were performing a working memory task in fMRI. At light onset, blue light, as compared to green light, increased activity in the left hippocampus, left thalamus, and right amygdala. During the task, blue light, as compared to violet light, increased activity in the left middle frontal gyrus, left thalamus and a bilateral area of the brainstem consistent with activation of the locus coeruleus.

Conclusion/Significance

These results support a prominent contribution of melanopsin-expressing retinal ganglion cells to brain responses to light within the very first seconds of an exposure. The results also demonstrate the implication of the brainstem in mediating these responses in humans and speak for a broad involvement of light in the regulation of brain function.