The oyster Crassostrea gigas was introduced in Spain for aquaculture purposes; however, until now, it is not known whether populations are established in the wild, being necessary to define whether this species is spawning and which environmental variables trigger this process. The influence of environmental parameters on the reproduction of C. gigas was evaluated from January 2008 to October 2009 with oysters grown on a raft in the Ría de Arousa (Galicia, NW Spain). Temperature and chlorophyll a are directly correlated to sexual maturation. Oysters can mature at temperatures below 14°C. The temperature necessary for spawning differs between the sexes, requiring a temperature above 15°C for males and 18°C for females. Females had a single massive spawn between June and September, while males had partial spawning from May to December with two peaks, one in May–September and another in October–December, with the second peak more pronounced. The first spawning peak is related to high temperatures and concentrations of chlorophyll a, and the second spawning peak is mainly related to the food availability in the water. The spawning asynchrony may be impeding establishment of wild C. gigas populations in Spain. 相似文献
Hypertension (HTN), i.e. abnormally high blood pressure, is a major risk factor for heart attack, stroke, and kidney failure. The Epithelial Sodium Channel (ENaC), one of the main transporters regulates blood pressure by tightly controlling the sodium reabsorption along the nephron. Recently, we have shown an α-ENaC overexpression in platelets from hypertensive patients compared to platelets from normotensive subjects, suggesting it makes a contribution to the activation state of platelets and the physiopathology of hypertension. However, the involvement of the α-ENaC localized in neutrophils to this disease remains unknown. Neutrophils are the first leukocytes to be recruited to an inflammatory site and are equipped with a strong ability to eliminate intra- or extracellular pathogens using reactive oxygen species or antibacterial proteins contained in their granules.Using the Western blotting (Wb), flow cytometry, and qRT-PCR approaches; we determined α-ENaC neutrophil overexpression at the protein and messenger RNA (mRNA) levels. By confocal and cytometry analysis, we determined the α-ENaC distribution and the heterogeneity of HTN neutrophils population, respectively. Immunoprecipitation and Wb assays demonstrated the presence of both α-ENaC and caveolin-1 phosphorylated forms, compared with neutrophils from healthy individuals. Although neutrophils from hypertensive subjects circulating in an activated state were exhibiting important oxidative stress and modifications registered by confocal, atomic force, and scanning electron microscope, they conserved their defense capabilities. The features described above for neutrophils from hypertensive patients could be attributed to α-ENaC overexpression, as its drug inhibition diminished their activation state modulating the actin cytoskeleton reorganization triggered during the activation process. 相似文献
The geographic distributions of Hylonycteris underwoodi and Thyroptera tricolor in Honduras have been established with specimens collected more than 50 years ago. Here, we describe the occurrence of these bat species captured in the historic city of Ciudad Blanca, Gracias a Dios in northeastern Honduras. 相似文献
Scientific evidence has shown the nutritional importance of boron (B) in the remodeling and repair of cancellous bone tissue. However, the effects of the nutritional deficiency of B on the cortical bone tissue of the appendicular skeleton have not yet been described. Thus, a study was performed to histomorphometrically evaluate the density of osteocyte lacunae of cortical bone of mouse femora under conditions of nutritional deficiency of B and to analyze the effects of the deficiency on the biomechanical properties of mouse tibiae. Weaning, 21-day-old male Swiss mice were assigned to the following two groups: controls (B+; n = 10) and experimental (B−; n = 10). Control mice were fed a basal diet containing 3 mg B/kg, whereas experimental mice were fed a B-deficient diet containing 0.07 mg B/kg for 9 weeks. The histological and histomorphometric evaluations of the mice fed a B-deficient diet showed a decrease in the density of osteocyte lacunae in the femoral cortical bone tissue and the evaluation of biomechanical properties showed lower bone rigidity in the tibia.
Obligate avian brood parasites lay stronger eggs than their hosts or non‐parasitic relatives because they are rounder and have a thicker eggshell. Additionally, some other characteristics of the brood parasitic eggshells related to their microstructure such as size and orientation of calcite crystal units could also contribute to generating even stronger shells. An eggshell microstructure formed by small randomly oriented calcite crystal units can increase the robustness of the eggshells of birds. Here, the eggshell microstructure of avian brood parasites as well as their hosts have been characterized in detail, using X‐ray diffraction analyses to estimate the size and degree of orientation of calcite crystal units making the eggshell. Specifically, the brood parasitic great spotted cuckoo Clamator glandarius and two hosts (jackdaws Corvus monedula and magpie Pica pica) and one non‐host species (the pigeon, Columba livia domestica) were considered. Calcite crystal of the eggshell of the brood parasitic species was smaller and more randomly oriented than those of the eggshells of non‐parasitic species, which suggest that eggshell microstructure would contribute to explain why parasitic eggs are more resistant to breakage than those of their hosts. 相似文献
The ability of cells to acquire resistance to multiple pharmaceuticals, namely multidrug resistance (MDR), is often mediated by the over-expression of efflux transporters of the ATP-binding cassette (ABC) superfamily; for example P-glycoprotein (P-gp or MDR1), breast cancer resistance protein (BCRP or ABCG2), and multidrug resistance-associated protein MRP1. ABCs pump drug molecules out of cells against a concentration gradient, reducing their intracellular concentration. The ability of polymeric amphiphiles to inhibit ABCs as well as the cellular pathways involved in the inhibition has been extensively investigated. This work investigated for the first time the effect of branched poly(ethylene oxide)-poly(propylene oxide) block copolymers (poloxamines) on the levels of mRNA encoding for MDR1, BCRP and MRP1, in a human hepatoma cell line (Huh7). Copolymers with a broad range of molecular weights and hydrophilic-lipophilic balances were assayed. Results confirmed the down-regulation of mdr1 and abcg2 genes. Conversely, the mrp1 gene was not affected. These findings further support the versatility of these temperature- and pH-responsive copolymers to overcome drug resistance in cancer and infectious diseases. 相似文献
CD178 (CD95-ligand) is expressed on several tumor cells and likely influences the interaction of the tumor with the host immune system. However, little is known about the mechanisms that regulate its expression on the cell surface. We have evaluated the ability of various compounds and cytokines to regulate cell surface expression and release of soluble CD178 in various carcinoma cell lines. Vitamin E succinate (VES) and retinoic acid (RA) were found to reduce CD178 surface expression, whereas interferon-gamma stimulated a slight upregulation. At 48 h, the regulation of surface CD178 by VES and RA arose from a small decrease in CD178 mRNA and to a greater extent due to an increase in the release of soluble CD178; the latter was blocked by addition of a metalloproteinase inhibitor. Accordingly, VES and RA treatment diminished the ability of tumor cells to kill CD95-sensitive cells and this effect was markedly reduced by the presence of a metalloproteinase inhibitor. Our results indicate that, in vitro, CD178 expression on the cell surface of tumor cells can be regulated by agents that alter both expression and release of the ligand. In vivo, such treatments may play an important role in the outcome of tumor sensitivity or resistance to host immune mechanisms. 相似文献
Fragmentation of lowland tropical rain forests has resulted in loss of animal and plant species and isolation of remaining populations that puts them at risk. At Los Tuxtlas. Mexico, lowland rain forests are particularly diverse in the bat fauna they contain and while most of the forests have been fragmented by human activity, many of the fragments still harbor diverse assemblages of bat species. To assess the effectiveness of corridors, among other options, to ameliorate the negative effects of fragmentation, we investigated bat species richness and relative abundance in one 6 km long section of live fences (LF) bordering a dirt road and in three 6 km long sections of residual forest vegetation along the sides of three permanent streams (BS. MS. HS). Netting of bats resulted in the capture of 967 bats. At the LF site we captured 12 bat species. 15 at the BS site. 18 at the MS site and 23 at the HS site. Species richness was associated with average area of forest fragments within a 1000 m band on each side of each corridor (r = 0.97. p = 0.01). Only 28% of the species were common among sites. Frugivorous and insectivorous species accounted for 48% each of bat captures while nectarivores accounted for 3%, sanguinivores for 0.5% and carnivore-frugivores for 0.5% Edge habitat species such as Pteronotus parnelli and Sturnira lilium accounted for 50% of the captiures. Frugivorous species such as Carollia brevicauda. Vampyrodes caraccioli. Dermanura phaeotis, D. toltecus and A. jamaicensis accounted for another 25% of bat captures. Recaptures of bats indicated bat movements from forest fragments to corridors and between corridors, with recapture distances ranging from 200 to 2000 m. Within corridor recaptures separated by several months from the original recapture date indicated individual bat revisitation to these sites. We discuss the value of these corridors to bats as stepping stones in the fragmented landscape. 相似文献
Infection by the bacterium Listeria monocytogenes depends on host cell clathrin. To determine whether this requirement is widespread, we analyzed infection models using diverse bacteria. We demonstrated that bacteria that enter cells following binding to cellular receptors (termed "zippering" bacteria) invade in a clathrin-dependent manner. In contrast, bacteria that inject effector proteins into host cells in order to gain entry (termed "triggering" bacteria) invade in a clathrin-independent manner. Strikingly, enteropathogenic Escherichia coli (EPEC) required clathrin to form actin-rich pedestals in host cells beneath adhering bacteria, even though this pathogen remains extracellular. Furthermore, clathrin accumulation preceded the actin rearrangements necessary for Listeria entry. These data provide evidence for a clathrin-based entry pathway allowing internalization of large objects (bacteria and ligand-coated beads) and used by "zippering" bacteria as part of a general mechanism to invade host mammalian cells. We also revealed a nonendocytic role for clathrin required for extracellular EPEC infections. 相似文献