Implication of Paleovegetational Changes in Diaojiao Lake,Inner Mongolia

Pollen analysis resulted from 111 core samples from Diaojiao (DJ) Lake Inner Mongolia have shown the highest value of total pollen accumulati6n rate was more than 20000 grains · cm-2 · a-1 and lowest was 80～90 grains ·cm-2 · a- 1. In general, the arboreal pollen was more than 50%, up to 80%, including the following families and genera: Pinus, Betula, ,Picea, Carpinus, Ouercus, Ulrnus etc. The non-arboreal pollen consist of 27 types, which mainly include Artemisia, Ephedra, Chenopodiaceae, Compositae, Gramineae, Leguminosae, Labiatae, Nitraria. Polygonaceae, Ranunculus, Thalictrurn, Umbelliferae, Caryophyllaceae and Cyperaceae etc. Fern spores, aquatic pollen and algae were also observed off and on in the DJ core. A pollen diagram, of five pollen assemblage zones was established through stratigraphically constrained cluster analysis,using the method of incremental sum of squares. It shows two peaks appearing at about 6.3 and 5.1 ka BP in the curve of total pollen accumulation rate. The first peak reflects a humid period and the second an arid period. The study indicated that Holocene climatic and vegetational changes in Inner Mongolia can be recongnized at different time scales (e. g. thousands, hundreds of years, or even much shorter time scale). In addition, the humidity in that area during those time was higher than today, with dominent climate humid-cool or humid-warm during most of the Holocene time on account of the lower vaporization and high altitude (1800 ma. s. 1. ).     

Natural history predicts patterns of thermal vulnerability in amphibians from the Atlantic Rainforest of Brazil

In the Brazilian Atlantic Rainforest (AF), amphibians (625 species) face habitat degradation leading to stressful thermal conditions that constrain animal activity (e.g., foraging and reproduction). Data on thermal ecology for these species are still scarce. We tested the hypothesis that environmental occupation affects the thermal tolerance of amphibian species more than their phylogenetic relationships. We evaluated patterns of thermal tolerance of 47 amphibian species by assessing critical thermal maxima and warming tolerances, relating these variables with ecological covariates (e.g., adult macro‐ and microhabitat and site of larval development). We used mean and maximum environmental temperature, ecological covariates, and morphological measurements in the phylogenetic generalized least squares model selection to evaluate which traits better predict thermal tolerance. We did not recover phylogenetic signal under a Brownian model; our results point to a strong association between critical thermal maxima and habitat and development site. Forest species were less tolerant to warm temperatures than open area or generalist species. Species with larvae that develop in lentic environment were more tolerant than those in lotic ones. Thus, species inhabiting forest microclimates are more vulnerable to the synergistic effect of habitat loss and climate change. We use radar charts as a quick evaluation tool for thermal risk diagnoses using aspects of natural history as axes.     

Effects of acute treatment with dexamethasone on hemodynamic and histopathological changes in rats

Abstract

We assessed the time-dependent effects of intraperitoneal (i.p.) and intravenous (i.v.) application of dexamethasone (Dexa) on the mean arterial blood pressure (MAP), heart rate (HR) and total blood volume (TBV). We evaluated also the relation between the effects and immunoreactivities of transforming growth factor-beta (TGF-β), epithelial nitric oxide synthase (eNOS), interleukin-1 beta (IL1-β) and vascular endothelial growth factor (VEGF) in rat brain, lung and kidney tissues. Rats were anesthetized and while still breathing spontaneously, a tracheotomy and femoral vein and artery catheterizations were performed. To determine TBV using the hemodilution method, 2 ml albumin-electrolyte solutions were applied by i.v. injection. Group 1 (control group) received a 1 ml bolus injection of physiologic saline, Group 2 received 15 mg/kg and Group 3 received 75 mg/kg Dexa i.p. The hematocrit was measured at 10, 20, 60 and 120 min. For each animal, the values of MAP, HR and TBV were measured within 2 h. For immunohistochemical evaluation, anti-TGF-β, anti-eNOS, anti-IL1-β and anti-VEGF primary antibodies were tested using the avidin-biotin-peroxidase method. TBV was decreased in Group 1 and the increase in MAP was statistically significant. HR values increased slightly. None of the values changed significantly in Group 2. Although TBV was unchanged in Group 3, the decrease in MAP was statistically significant. HR values increased, but the increase was not statistically significant. Mild IL1-β immunoreactivity and moderate TGF-β, eNOS and VEGF immunoreactivities were observed in the brain, lung and kidney samples in Group 1. Increased eNOS immunoreactivity in the kidney samples were observed in Group 2. eNOS immunoreactivity was as strong in the brain and the kidney samples in Group 3. Decreased VEGF immunoreactivity was observed in the lung and kidney tissues in Group 3. Significantly decreased TGF-β immunoreactivity was observed in all tissue samples in Group 3. The decreased MAP values in Group 3 differed from those in Groups 1 and 2. Despite increased eNOS immunoreactivity, especially in brain and kidney, the decrease in VEGF immunoreactivity in Group 3, especially lung and kidney, were consistent with a drop in blood pressure.     

Belowground biodiversity in a Mediterranean landscape: relationships between saprophagous macroarthropod communities and vegetation structure

Millipedes and woodlice were sampled at 27 sites in a mosaic landscape in order to establish the extent to which the macroarthropod community changed with different plant formations. Multivariate analyses conducted on abundance data for ten species revealed four main types of macroarthropod communities. This classification was highly correlated with vegetation structure and particularly the degree of openness of the sites. Communities dominated by Ommatoiulus rutilans (Julidae) occurred in open grassland; those dominated by Glomeris marginata (Glomeridae) plus Porcellio gallicus (Porcellionidae) were found at the least open sites, with a high oak cover; communities with a high proportion of the endemic glomerid Glomeris annulata occurred in semi-open sites with a substantial cover of shrubs. Species diversity was significantly higher at the semi-open sites, this being interpreted as an edge effect. Population density and biomass were lower at wooded sites. In the context of a regional trend towards woodland expansion, the results are discussed from the viewpoint of conserving the pool of millipede and woodlouse species and of maintaining the abundance of saprophagous macroarthropods in the region's ecosystems.     

Problems in Fitting a Cosine Curve: Short Communications

In fitting of cosine curves latent experimental inequalities due to a serial effect have to be excluded. Though cosinor analysis may be sufficient then, inclusion of biological time, i.e. not fitting values to time but to a function of time, will lead to further improvement.     

EFFECT OF NITROGEN STARVATION ON THE BIOCHEMISTRY OF PHORMIDIUM LAMINOSUM (CYANOPHYCEAE)1

Cells of the non-N₂-fixing cyanobacterium Phormidium laminosum (Agardh) Gomont (strain OH-1-pCl₁) showed doubling times of 24 h in media containing nitrate and 120 h in media without a nitrogen source. Nitrogen starvation resulted in a drastic decrease in the cellular content of chlorophyll, phycobiliproteins (phycocyanin and allophycocyanin), and other soluble proteins, although the total protein of cells was unchanged. N-starved cells showed an exocellular layer of mucilage that rapidly increased with starvation time. The appearance of N deficiency symptoms was strongly dependent on culture conditions, and it was faster under the optimal conditions used for cell growth. The relative content of C and N of nitrate-grown cells remained more or less constant during all growth phases (C/N ratio of ca. 5) but diminished at different rates in N-starved cells. Cells subjected to N starvation for 48 h had a C/N ratio of more than 10. N starvation also resulted in the selective degradation of soluble poly-peptides of masses lower than 20 kDa (which include those constituting phycobiliproteins), whereas the relative content of soluble polypeptides of greater size increased.     

Developmental changes in neutral glycosphingolipids of mouse placenta

The mammalian placenta is a unique organ for the study of developmental changes. Placentas of laboratory animals such as the mouse allow for the determination of the exact stage of pregnancy, which cannot be achieved with human placenta. In this study, neutral glycosphingolipids were isolated from mouse (inbred strain C57BL/6) placentas, from day 10 to day 18 of gestation, and were separated by high performance thin layer chromatography. Densitometric measurements after orcinol staining showed, at day 10 of gestation, the presence of mono-, tetra-, tri- and dihexosylceramide in decreasing quantities, as well as four unidentified spots. On day 12, the glycosphingolipid composition changed with the disappearance of the unidentified spots and the appearance of an orcinol positive spot migrating similarly to the Forssman antigen; no further changes occurred between days 12 and 18 of gestation. The identity of the Forssman-like glycosphingolipid with the Forssman antigen was established by binding of¹²⁵I labelledHelix pomatia agglutinin (-GalNAc specific) to glycosphingolipids separated on high performance thin layer chromatography plates, and by the reaction of the isolated glycosphingolipid with a monoclonal anti-Forssman antibody. The appearance of the Forssman antigen at day 12 of gestation coincided with the day of final maturation of the mouse placenta and subsequent cessation of growth, suggesting a possible role of the glycosphingolipid during embryonic development.Abbreviations asialo-GM₁ Gal 3GalNAc4Gal4Glc1Cer - BCIP 5-bromo-4-chloro-3-indolylphosphate - DHC lactosylceramide, Gal4Glc1Cer - Forssman antigen GalNAc3GalNAc3Gal4Gal4Glc1Cer - globoside GalNAc3Gal4Gal4Glc1Cer - GSL glycosphingolipids - HPA Helix pomatia agglutinin - HPTLC high performance thin layer chromatography - MHC galactosylceramide, Gal1Cer - MHC glucosylceramide, Glc1Cer - PBS phosphate-buffered saline - PNA peanut agglutinin - PVP poly(vinylpyrrolidone), mol. wt 40 000 - SBA soybean agglutinin - THC trihexosylceramide, Gal4Gal4Glc1Cer. To whom correspondence should be addressed.     

Modeling conformational states of proteins with AlphaFold

Many proteins exert their function by switching among different structures. Knowing the conformational ensembles affiliated with these states is critical to elucidate key mechanistic aspects that govern protein function. While experimental determination efforts are still bottlenecked by cost, time, and technical challenges, the machine-learning technology AlphaFold showed near experimental accuracy in predicting the three-dimensional structure of monomeric proteins. However, an AlphaFold ensemble of models usually represents a single conformational state with minimal structural heterogeneity. Consequently, several pipelines have been proposed to either expand the structural breadth of an ensemble or bias the prediction toward a desired conformational state. Here, we analyze how those pipelines work, what they can and cannot predict, and future directions.