Lipid organization regulates annexin A2 Ca2 +-sensitivity for membrane bridging and its modulator effects on membrane fluidity

Annexin A2 (AnxA2) is a phospholipid binding protein that has been implicated in many membrane-related cellular functions. AnxA2 is able to bind different acidic phospholipids such as phosphatidylserine (PS) and phosphatidylinositol-4,5-bisphosphate (PI2P). This binding is mediated by Ca^2 +-dependent and Ca^2 +-independent mechanisms. The specific functions of annexin A2 related to these two phospholipids and the molecular mechanisms involved in their interaction remain obscure. Herein we studied the influence of lipid composition on the Ca^2 +-dependency of AnxA2-mediated membrane bridging and on membrane fluidity. Membrane models of ten different lipid compositions and detergent-resistant membranes from two cellular sources were investigated. The results show that the AnxA2-mediated membrane bridging requires 3 to 50 times less calcium for PS-membranes than for PI2P-membranes. Membrane fluidity was measured by the ratiometric fluorescence parameter generalized polarization method with two fluorescent probes. Compared to controls containing low phospholipid ligand, AnxA2 was found to reduce the membrane fluidity of PI2P-membranes twice as much as the PS-membranes in the presence of calcium. On the contrary, at mild acidic pH in the absence of calcium AnxA2 reduces the fluidity of the PS-membranes more than the PI2P-membranes. The presence of cholesterol on the bilayer reduced the AnxA2 capacity to reduce membrane fluidity. The presented data shed light on the specific roles of PI2P, PS and cholesterol present on membranes related to the action of annexin A2 as a membrane bridging molecule during exocytosis and endocytosis events and as a plasma membrane domain phospholipid packing regulator.     

Are reclamo hunting seasons for the Spanish red-legged partridge off the mark?

The red-legged partridge (Alectoris rufa) is abundant in a number of regions in Spain and one of the most commonly hunted small game species in the country. Partridge hunting generates substantial income in rural areas where agriculture is less profitable. A traditional hunting method, reclamo hunting, is currently under revision by the European Commission's (EC) Birds Directive because hunting may fall within the reproduction period of the species. So far, only limited data on the reproductive phenology of the species exist to inform a policy change. In this study, we present reproduction data for red-legged partridges from 9 hunting estates in Andalusia during 1 year, and over 3 consecutive seasons from a control estate. We used direct nest and partridge chick covey observations to estimate 165 egg-laying dates. We found significant differences between sites related to altitude during reproduction periods. Using our pooled data, we showed that reproduction occurred between the last 10 days in January and the middle of February; beyond 31 January we observed an exponential increase in birds reproduction. According to these data and current EC legislation, reclamo hunting should not extend beyond 31 January. © 2012 The Wildlife Society.     

Comparative analysis of methanogen diversity in the rumen of crossbred buffalo and cattle in the Philippines by using the functional gene mcrA

Comparative analyses of methanogen diversity in the rumen of crossbred buffalo and cattle fed the same diet in the Philippines was performed by cloning the methyl coenzyme M reductase A (mcrA) gene. The cattle and buffalo libraries consisted of 50 clones each. Comparative analysis of the amino acid sequence revealed that these 2 libraries differed significantly (P?<?0.01). The deduced amino acid sequences of the clones were classified into 9 operational taxonomic units (OTUs) in buffalo and 11 OTUs in cattle. Sequence similarity between the clones and known cultured methanogens ranged from 86 to 97?% for buffalo and 84 to 99?% for cattle. Methanobrevibacter species were predominant in buffalo (64?% of the clones), and an unknown mcrA was predominant in cattle (52?% of the clones). A large number of clones with low similarity to cultivated methanogens was observed in both buffalo and cattle, suggesting the presence of an unknown methanogen species in their rumen.     

Biochemical behaviour of an incidentally diagnosed silent corticotroph adenoma

Silent corticotroph adenoma (SCA) is a non-functioning macroadenoma that has positive immunoreactivity for ACTH. Few studies have evaluated the biochemical behaviour of these tumours. We present the case of a 65-year-old male incidentally diagnosed with SCA, in which an exhaustive study of the corticotroph axis was conducted.     

Characterization of a distinctive pattern of periovulatory leptin secretion and its relationship with ovulation rate and luteal function in swine with obesity/leptin resistance

Patterns of leptin secretion during the estrous cycle and the possible relationship of changes in circulating leptin during the periovulatory period with ovarian function in sows of obese (Iberian breed) and lean genotype (Large White×Landrace) were evaluated in two consecutive experiments. Plasma leptin concentrations throughout the estrous cycle in lean sows remain unchanged, but Iberian females showed a periovulatory increase in circulating leptin levels without associated changes in body condition and fatness. In these sows, plasma leptin concentrations at Days -1 and 0 of the cycle were found to be positively correlated with the ovulation rate (r=0.943 and r=0.987, respectively; P<0.05 for both), but the levels of leptin at Day 0 were negatively correlated with the progesterone release from Day 3 (r=-0.557; P<0.05) and, became more evident at Day 5 of the estrous cycle (r=-0.924; P<0.005). Such relationships were not observed in the females of the lean genotype. In conclusion, the present study indicates the existence of a distinctive pattern in the periovulatory leptin secretion in swine with obesity and leptin resistance, which is associated with the number and functionality of the corpora lutea present in the subsequent cycle.     

Ornamentation of achene silica walls and its contribution to the systematics of <Emphasis Type="Italic">Eleocharis</Emphasis> (Cyperaceae)

Micromorphology of the achene surface of 26 Brazilian species of Eleocharis was studied by scanning electron microscopy in order to evaluate its usefulness in the taxonomy of the genus. The results point out two patterns of cell organization according to silica structures of achenes. The first corresponds to a group of species (group A) that have small to medium cells arranged vertically. The second is found in those species (group B) with medium to large cells arranged horizontally. These data were useful in separating species of Eleocharis subgenus Scirpidium and E. subgenus Limnochloa (group B) from E. subgenus Eleocharis (group A). However, group A shows considerable variation in silica wall arrangement. Eleocharis squamigera, previously considered as part of E. subgenus Eleocharis, shows features rather similar to those of Scirpidium, confirming recent phylogenies. The subgenus Limnochloa was clearly distinguished from others by achenes with large cells (over 55 μm width), presence of crenate or repand anticlinal walls, and some orifices near the wall in some species. The silica wall ornamentation seems to be a useful morphological tool for studying relationships between subgenera and distinguishes Limnochloa from the other subgenera.     

Extracellular sunflower proteins: evidence on non-classical secretion of a jacalin-related lectin

Extracellular proteins from sunflower seedlings were analyzed by electrophoresis followed by peptide mass fingerprinting. Tentative identification revealed novel proteins for this crop. A significant number of those proteins were not expected to be extracellular because they lacked the typical signal peptide responsible for secretion. In silico analysis showed that some members of this group presented the characteristic disordered structures of certain non-classical and leaderless mammalian secretory proteins. Among these proteins, a putative jacalin-related lectin (Helja) with a mannose binding domain was further isolated from extracellular fluids by mannose-affinity chromatography, thus validating its identification. Besides, immunolocalization assays confirmed its extracellular location. These results showed that a lectin, not predicted to be secreted in strict requirement of the N-terminal signal peptide, occurs in a sunflower extracellular compartment. The implications of this finding are discussed.     

Do the phenology and functional stem attributes of woody species allow for the identification of functional groups in the semiarid region of Brazil?

The phenology of tree species in environments that are subject to strong climatic seasonality is mainly determined by water availability, which may vary as a function of wood density. The relationship among phenology, water potential, wood density and the capacity of water storage in the stem were determined for woody species of caatinga vegetation (dry forest) in the semiarid region of NE Brazil. Leaf flush and fall, flowering and fruiting events were recorded over a 31-month period, and the water potential was measured over a two-year period. These data were related to precipitation, water availability in the soil and photoperiod. Seven deciduous species exhibited low wood density (DLWD,?<0.5?g?cm^?3), high capacity of water storage in the stem (until 250?% of the dry weight) and high water potential during the year, as opposed to 15 deciduous species that showed high wood density (DHWD,?≥0.5?g?cm^?3). Leaf flush, flowering and the fruiting of DHWD species were related to precipitation, whereas these phenological events occurred at the end of the dry season and/or the beginning of the rainy season for DLWD species and were related to the photoperiod. The two evergreen species showed variations of water potential that were intermediate between those of DHWD and DLWD deciduous species, leaf flush during the dry season and flowering at the end of dry season. These results suggest the existence of three functional groups: evergreen species, DHWD deciduous species and DLWD deciduous species.     

Super-induction of Dicer-2 expression by alien double-stranded RNAs: an evolutionary ancient response to viral infection?

Dicer-2 is a ribonuclease involved in the insect RNAi pathway. On attempting to knockdown Dicer-2 expression in the insect Blattella germanica by RNAi, we found that treatment with Dicer-2 dsRNA upregulated the targeted mRNA. This unexpected result was also observed after treating with a nucleopolyhedrovirus dsRNA. Experiments with this alien dsRNA showed an all-or-none response with a threshold for inducing Dicer-2 upregulation between 0.4 and 0.04 μg in terms of dsRNA concentration and between 50 and 20 bp in terms of dsRNA length. The response seems specific of dsRNA given that equivalent experiments carried out with dsDNA did not affect Dicer-2 expression. In insects, Dicer-2 is postulated to be a sensor of viral infections and a key antiviral defense element. The upregulation of Dicer-2 expression after dsRNA administration fits well with this sensor role, and the occurrence of this mechanism in B. germanica, a phylogenetically basal insect, suggests that sensing alien RNAs might be an ancestral function of Dicer-2 proteins.     

Integrated versus stand-alone second generation ethanol production from sugarcane bagasse and trash

Ethanol production from lignocellulosic materials is often conceived considering independent, stand-alone production plants; in the Brazilian scenario, where part of the potential feedstock (sugarcane bagasse) for second generation ethanol production is already available at conventional first generation production plants, an integrated first and second generation production process seems to be the most obvious option. In this study stand-alone second generation ethanol production from surplus sugarcane bagasse and trash is compared with conventional first generation ethanol production from sugarcane and with integrated first and second generation; simulations were developed to represent the different technological scenarios, which provided data for economic and environmental analysis. Results show that the integrated first and second generation ethanol production process from sugarcane leads to better economic results when compared with the stand-alone plant, especially when advanced hydrolysis technologies and pentoses fermentation are included.