Mitochondrial lipids in Bufo arenarum full-grown oocytes

Both the content and composition of polar and neutral lipids from the mitochondrial fraction of ovarian full-grown Bufo arenarum oocytes were analysed in the present study. Triacylglycerols (TAG) represent 33% of the total lipids, followed by phosphatidylcholine (PC), free fatty acids (FFA) and phosphatidylethanolamine (PE). Diphosphatidylglycerol (DPG) or cardiolipin, a specific component of the inner mitochondrial membrane, represents about 4% of the total lipid content. Palmitic (16:0) and arachidonic (20:4n6) acids are the most abundant fatty acids in PC and PE, respectively. DPG is enriched in fatty acids with carbon chain lengths of 18, the principal component being linoleic acid. In phosphatidylinositol (PI), 20:4n6 and stearic acid (18:0) represent about 72 mol% of the total acyl group level. The main fatty acids in TAG are linoleic (18:2), oleic (18:1), and palmitic acids. The fatty acid composition of FFA and diacylglycerols (DAG) is similar, 16:0 being the most abundant acyl group. PE is the most unsaturated lipid and sphingomyelin (SM) has the lowest unsaturation index.     

Seasonality in coastal benthic ecosystems

For historical reasons, knowledge about seasonality in the dynamics of marine benthic suspension feeders from temperate areas comes mainly from studies of cold temperate seas. Recent surveys of Mediterranean taxa show different patterns from those observed in cold temperate seas, which are characterized by winter dormancy. In the Mediterranean, summer dormancy predominates among taxa and appears to be related to energetic constraints. Temperature and food availability are crucial to the dynamics of benthic suspension feeders. However, because these factors tend to be positively correlated in cold temperate seas, it is difficult to distinguish between their effects. Such correlation does not occur in Mediterranean ecosystems. The contrast between recent studies in the Mediterranean and in other areas can help to disentangle confounded environmental controls.     

Heterologous protein production using euchromatin-containing expression vectors in mammalian cells

Upon stable cell line generation, chromosomal integration site of the vector DNA has a major impact on transgene expression. Here we apply an active gene environment, rather than specified genetic elements, in expression vectors used for random integration. We generated a set of Bacterial Artificial Chromosome (BAC) vectors with different open chromatin regions, promoters and gene regulatory elements and tested their impact on recombinant protein expression in CHO cells. We identified the Rosa26 BAC as the most efficient vector backbone showing a nine-fold increase in both polyclonal and clonal production of the human IgG-Fc. Clonal protein production was directly proportional to integrated vector copy numbers and remained stable during 10 weeks without selection pressure. Finally, we demonstrated the advantages of BAC-based vectors by producing two additional proteins, HIV-1 glycoprotein CN54gp140 and HIV-1 neutralizing PG9 antibody, in bioreactors and shake flasks reaching a production yield of 1 g/l.     

Intrinsic Patterns of Coupling between Correlation and Amplitude of Low-Frequency fMRI Fluctuations Are Disrupted in Degenerative Dementia Mainly due to Functional Disconnection

Low frequency fluctuations (LFFs) of the BOLD signal are a major discovery in the study of the resting brain with functional magnetic resonance imaging (fMRI). Two fMRI-based measures, functional connectivity (FC), a measure of signal synchronicity, and the amplitude of LFFs (ALFF), a measure of signal periodicity, have been proved to be sensitive to changes induced by several neurological diseases, including degenerative dementia. In spite of the increasing use of these measures, whether and how they are related to each other remains to be elucidated. In this work we used voxel-wise FC and ALFF computed in different frequency bands (slow-5: 0.01-0.027 Hz; slow-4: 0.027-0.073 Hz; and full-band: 0.01-0.073 Hz), in order to assess their relationship in healthy elderly as well as the relevant changes induced by Alzheimer’s Disease (AD) and Mild Cognitive Impairment (MCI). We found that in healthy elderly subjects FC and ALFF are positively correlated in anterior and posterior cingulate cortex (full-band, slow-4 and slow-5), temporal cortex (full-band and slow-5), and in a set of subcortical regions (full-band and slow-4). These correlation patterns between FC and ALFF were absent in either AD or MCI patients. Notably, the loss of correlation between FC and ALFF in the AD group was primarily due to changes in FC rather than in ALFF. Our results indicate that degenerative dementia is characterized by a loss of global connection rather than by a decrease of fluctuation amplitude.     

Red Coral Fishery at the Costa Brava (NW Mediterranean): Case Study of an Overharvested Precious Coral

Abstract The Mediterranean red coral (Corallium rubrum, L. 1758) is a slow-growing longevous gorgonian that produces a red calcium carbonate skeleton, which is in high demand by the jewellery industry. Its long history of intensive commercial harvesting has resulted in a well-documented decline of its stocks throughout the Mediterranean, becoming especially apparent during the last two decades. Based on the extensive ecological data from the Costa Brava (NE Spain) stocks, this study reviews, for the first time, socioeconomic aspects and the impact of current fishing practices on the red coral population structure and reproductive biology. A comparison of the intensively harvested populations in shallow water with that of the infrequently harvested ones in deep water, along with a population in a marine reserve as well, reveals that 98% of all shallow water colonies show a juvenile size and branching pattern as a result of harvesting. Recent data on the reproductive biology of the species show that 91% of the colonies in shallow water populations (<60 m depth) are not 100% sexually mature. These populations are clearly at the limit of their recoverability potential. The maximum sustainable yield (estimated using the Beverton-Holt model) is reached at an age of first capture of 98 years, although the current regulations allow harvesting of approximately 11-year-old colonies (corresponding to a basal diameter of 7 mm). The presented data reveal how this renewable resource is being exploited in a clearly non-sustainable and inefficient way, changing significantly the underwater landscape of the Mediterranean coast. The review of all available data suggests that the shallow water stocks are depleted. Furthermore, recent trends in poaching of juvenile colonies and mass mortality events threaten the survival of the shallow water populations. A ban on reconstituted coral from the market appears to be the only option to control this form of poaching.     

Reduced KIR2DL1 recognition of MHC class I molecules presenting phosphorylated peptides

As initially described by K. Karre and colleagues in the missing self hypothesis, cells expressing self-MHC class I proteins are protected from NK cells attack. In contrast, reduction in the expression of MHC class I molecules due to viral infection or tumor transformation result in the killing of these "abnormal" cells by NK cells via NK-activating receptors. Thus, NK killing of target cells is determined by both negative signals coming from MHC class I proteins and by positive signals derived from the activating ligands. The bound peptide in MHC class I play an important role in the balanced recognition of NK cells. The peptide stabilizes the MHC complex and interacts directly with the NK inhibitory receptors, thus participating in the determination of the fate of the target cells. In this study we demonstrate that posttranslational modifications such as phosphorylation of the presented peptide altered the ability of NK cells to recognize MHC class I molecules. By using a consensus peptide (QYDDAVYKL) that binds HLA-Cw4 in which different positions in the bound peptide were modified by serine phosphorylation, we observed a reduction in KIR2DL1 binding that led to decreased protection from NK killing. Therefore, it might be possible that alteration in the phosphorylation pattern during tumor transformation or viral infection may result in less inhibition and, consequently, improved NK cell killing.     

Analysis of the human polynucleotide phosphorylase (PNPase) reveals differences in RNA binding and response to phosphate compared to its bacterial and chloroplast counterparts

PNPase is a major exoribonuclease that plays an important role in the degradation, processing, and polyadenylation of RNA in prokaryotes and organelles. This phosphorolytic processive enzyme uses inorganic phosphate and nucleotide diphosphate for degradation and polymerization activities, respectively. Its structure and activities are similar to the archaeal exosome complex. The human PNPase was recently localized to the intermembrane space (IMS) of the mitochondria, and is, therefore, most likely not directly involved in RNA metabolism, unlike in bacteria and other organelles. In this work, the degradation, polymerization, and RNA-binding properties of the human PNPase were analyzed and compared to its bacterial and organellar counterparts. Phosphorolytic activity was displayed at lower optimum concentrations of inorganic phosphate. Also, the RNA-binding properties to ribohomopolymers varied significantly from those of its bacterial and organellar enzymes. The purified enzyme did not preferentially bind RNA harboring a poly(A) tail at the 3' end, compared to a molecule lacking this tail. Several site-directed mutations at conserved amino acid positions either eliminated or modified degradation/polymerization activity in different manners than observed for the Escherichia coli PNPase and the archaeal and human exosomes. In light of these results, a possible function of the human PNPase in the mitochondrial IMS is discussed.     

Stochastic modelling of shifts in allele frequencies reveals a strongly polygynous mating system in the re‐introduced Asiatic wild ass

Small populations are prone to loss of genetic variation and hence to a reduction in their evolutionary potential. Therefore, studying the mating system of small populations and its potential effects on genetic drift and genetic diversity is of high importance for their viability assessments. The traditional method for studying genetic mating systems is paternity analysis. Yet, as small populations are often rare and elusive, the genetic data required for paternity analysis are frequently unavailable. The endangered Asiatic wild ass (Equus hemionus), like all equids, displays a behaviourally polygynous mating system; however, the level of polygyny has never been measured genetically in wild equids. Combining noninvasive genetic data with stochastic modelling of shifts in allele frequencies, we developed an alternative approach to paternity analysis for studying the genetic mating system of the re‐introduced Asiatic wild ass in the Negev Desert, Israel. We compared the shifts in allele frequencies (as a measure of genetic drift) that have occurred in the wild ass population since re‐introduction onset to simulated scenarios under different proportions of mating males. We revealed a strongly polygynous mating system in which less than 25% of all males participate in the mating process each generation. This strongly polygynous mating system and its potential effect on the re‐introduced population's genetic diversity could have significant consequences for the long‐term persistence of the population in the Negev. The stochastic modelling approach and the use of allele‐frequency shifts can be further applied to systems that are affected by genetic drift and for which genetic data are limited.