A comparative study on phyllosphere nitrogen fixation by newly isolated Corynebacterium sp. & Flavobacterium sp. and their potentialities as biofertilizer

A number of nitrogen fixing bacteria has been isolated from forest phyllosphere on the basis of nitrogenase activity. Among them two best isolates are selected and identified as Corynebacterium sp. AN1 & Flavobacterium sp. TK2 able to reduce 88 and 132 n mol of acetylene (10(8)cells(-1)h(-1)) respectively. They were grown in large amount and sprayed on the phyllosphere of maize plants as a substitute for nitrogenous fertilizer. Marked improvements in growth and total nitrogen content of the plant have been observed by the application of these nitrogen-fixing bacteria. An average 30-37% increase in yield was obtained, which is nearer to chemical fertilizer treatment. Comparatively better effect was obtained by application of Flavobacterium sp.     

Pattern and process in Amazon tree turnover, 1976-2001

Previous work has shown that tree turnover, tree biomass and large liana densities have increased in mature tropical forest plots in the late twentieth century. These results point to a concerted shift in forest ecological processes that may already be having significant impacts on terrestrial carbon stocks, fluxes and biodiversity. However, the findings have proved controversial, partly because a rather limited number of permanent plots have been monitored for rather short periods. The aim of this paper is to characterize regional-scale patterns of 'tree turnover' (the rate with which trees die and recruit into a population) by using improved datasets now available for Amazonia that span the past 25 years. Specifically, we assess whether concerted changes in turnover are occurring, and if so whether they are general throughout the Amazon or restricted to one region or environmental zone. In addition, we ask whether they are driven by changes in recruitment, mortality or both. We find that: (i) trees 10 cm or more in diameter recruit and die twice as fast on the richer soils of southern and western Amazonia than on the poorer soils of eastern and central Amazonia; (ii) turnover rates have increased throughout Amazonia over the past two decades; (iii) mortality and recruitment rates have both increased significantly in every region and environmental zone, with the exception of mortality in eastern Amazonia; (iv) recruitment rates have consistently exceeded mortality rates; (v) absolute increases in recruitment and mortality rates are greatest in western Amazonian sites; and (vi) mortality appears to be lagging recruitment at regional scales. These spatial patterns and temporal trends are not caused by obvious artefacts in the data or the analyses. The trends cannot be directly driven by a mortality driver (such as increased drought or fragmentation-related death) because the biomass in these forests has simultaneously increased. Our findings therefore indicate that long-acting and widespread environmental changes are stimulating the growth and productivity of Amazon forests.     

Local differentiation and plasticity in size and sex expression in jack-in-the-pulpit, Arisaema triphyllum (Araceae)

The size advantage hypothesis suggests that natural selection will favor size-dependent sex expression when one sex gains more than the other by being large. But members of a minority sex will also have a higher reproductive value, on average. Thus, an individual's reproductive success depends on the reproductive decisions made by neighboring individuals. As a result, the optimal relationship between size and sex may differ among populations. In Arisaema triphyllum, the probability for an individual to be female increases with size, regardless of the character measured. A reciprocal transplant experiment showed the relationship between size and sexual expression is environmentally plastic. Plants originating from our two study sites became female at a larger average size when grown at one site than when grown at the other. In addition to environmental influence on sex expression, the experiment demonstrated genetic differences in the relationship between size and sex. Plants collected from one site became female at a larger size than those from the other, regardless of where they were grown. Thus, while the environment in which an individual was grown had a substantial influence on its sex expression, populations only a few kilometers apart have genetically different relationships between size and sex.     

Growth Rate of the Microalga Tetraselmis suecica Changes the Biochemical Composition of Artemia Species

The impact of different microalgal semicontinuous cultures on growth and biochemical composition in the next link of the food chain was tested using the filter feeder Artemia species as a model. The marine microalga Tetraselmis suecica was cultured semicontinuously with renewal rates between 10% and 50% and used to feed Artemia. Microalgal cultures maintained with a low renewal rate that had biochemical composition similar to that of the stationary-phase cultures commonly used in aquaculture produced poor growth and survival and low food-conversion efficiency compared to cultures maintained with a high renewal rate. Changes in the renewal rate in microalgal cultures also resulted in important changes in the gross biochemical composition of the filter feeder. The gross biochemical composition of the Artemia resembled that of the microalgae used as food except for total lipid content. The percentage of protein in the organic fraction of Artemia increased from 45% to 65% of the organic weight with increasing renewal rates in the microalgal cultures, while the carbohydrate percentage decreased under the same conditions. Higher renewal rates resulted in higher lipid percentages in the microalga, but in Artemia the percentage of lipids decreased from 19% of the organic weight with a renewal rate of 10%, to 13% with a renewal rate of 50%. The percentage of all polyunsaturated fatty acids in Artemia, including 20:5n-3, increased slightly with increasing renewal rates in the microalgal cultures. Results emphasize the importance of controlling microalgal nutritional value for the success of aquaculture food chains in which filter feeders are involved. Received October 15, 2000; accepted December 29, 2000.     

Linking sister chromatid cohesion and apoptosis: role of Rad21

Rad21 is one of the major cohesin subunits that holds sister chromatids together until anaphase, when proteolytic cleavage by separase, a caspase-like enzyme, allows chromosomal separation. We show that cleavage of human Rad21 (hRad21) also occurs during apoptosis induced by diverse stimuli. Induction of apoptosis in multiple human cell lines results in the early (4 h after insult) generation of 64- and 60-kDa carboxy-terminal hRad21 cleavage products. We biochemically mapped an apoptotic cleavage site at residue Asp-279 (D(279)) of hRad21. This apoptotic cleavage site is distinct from previously described mitotic cleavage sites. hRad21 is a nuclear protein; however, the cleaved 64-kDa carboxy-terminal product is translocated to the cytoplasm early in apoptosis before chromatin condensation and nuclear fragmentation. Overexpression of the 64-kDa cleavage product results in apoptosis in Molt4, MCF-7, and 293T cells, as determined by TUNEL (terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling) and Annexin V staining, assaying of caspase-3 activity, and examination of nuclear morphology. Given the role of hRad21 in chromosome cohesion, the cleaved C-terminal product and its translocation to the cytoplasm may act as a nuclear signal for apoptosis. In summary, we show that cleavage of a cohesion protein and translocation of the C-terminal cleavage product to the cytoplasm are early events in the apoptotic pathway and cause amplification of the cell death signal in a positive-feedback manner.     

Urinary proteins with pro-apoptotic and antitumor activity

Analysis of the protein composition of urine has been the subject of much research that has captured the interest of scientific groups over the years. A number of factors have been isolated from urine that possess anti-neoplastic activities as seen both in vitro and in vivo studies. The urine from pregnant women and commercial preparations of crude clinical grade human chorionic gonadotropin contain factors (HAF for hCG associated factor) with anti-Kaposi's sarcoma activity. Also found in urine with activity are eosinophil-derived neurotoxin (EDN), anti-neoplastic urinary protein (ANUP), inhibin, activin A, and angiostatin. The anti-cancer activity of urinary proteins is associated with apoptosis of endothelial cells and of tumor-associated endothelial cells. A better understanding of the biological functions of these various urinary proteins, and of others that remain to be discovered, should provide insights into novel cell regulatory systems operating during pregnancy.     

Trichophyton simii in a "Caí" monkey (Cebus apella) colony in the province of Corrientes, Argentina.

The objective is to describe an outbreak of Trichophyton simii in a Cebus apella monkey colony in Argentine. During summer, alopecic zones appeared on dorsal regions from head to base of the tail of the animals. The hair and skin of nine animals were streaked onto Sabouraud dextrose with cloramphenicol and incubated at 25 degrees C. By the 10th day, white, filamentous colonies, which turned pale pink, developed from simples of four animals. Microscopical examinations were carried out and, because of colony and macroconidia morphology, were classified as Trichopyton simii. Although infection with T. simii is considered a zoonosis, we did not find human cases.     

Biogeography of Parasitic Nematode Communities in the Galápagos Giant Tortoise: Implications for Conservation Management

The Galápagos giant tortoise is an icon of the unique, endemic biodiversity of Galápagos, but little is known of its parasitic fauna. We assessed the diversity of parasitic nematode communities and their spatial distributions within four wild tortoise populations comprising three species across three Galápagos islands, and consider their implication for Galápagos tortoise conservation programmes. Coprological examinations revealed nematode eggs to be common, with more than 80% of tortoises infected within each wild population. Faecal samples from tortoises within captive breeding centres on Santa Cruz, Isabela and San Cristobal islands also were examined. Five different nematode egg types were identified: oxyuroid, ascarid, trichurid and two types of strongyle. Sequencing of the 18S small-subunit ribosomal RNA gene from adult nematodes passed with faeces identified novel sequences indicative of rhabditid and ascaridid species. In the wild, the composition of nematode communities varied according to tortoise species, which co-varied with island, but nematode diversity and abundance were reduced or altered in captive-reared animals. Evolutionary and ecological factors are likely responsible for the variation in nematode distributions in the wild. This possible species/island-parasite co-evolution has not been considered previously for Galápagos tortoises. We recommend that conservation efforts, such as the current Galápagos tortoise captive breeding/rearing and release programme, be managed with respect to parasite biogeography and host-parasite co-evolutionary processes in addition to the biogeography of the host.     

The ABRF Metabolomics Research Group 2013 Study: Investigation of Spiked Compound Differences in a Human Plasma Matrix

Metabolomics is an emerging field that involves qualitative and quantitative measurements of small molecule metabolites in a biological system. These measurements can be useful for developing biomarkers for diagnosis, prognosis, or predicting response to therapy. Currently, a wide variety of metabolomics approaches, including nontargeted and targeted profiling, are used across laboratories on a routine basis. A diverse set of analytical platforms, such as NMR, gas chromatography-mass spectrometry, Orbitrap mass spectrometry, and time-of-flight-mass spectrometry, which use various chromatographic and ionization techniques, are used for resolution, detection, identification, and quantitation of metabolites from various biological matrices. However, few attempts have been made to standardize experimental methodologies or comparative analyses across different laboratories. The Metabolomics Research Group of the Association of Biomolecular Resource Facilities organized a “round-robin” experiment type of interlaboratory study, wherein human plasma samples were spiked with different amounts of metabolite standards in 2 groups of biologic samples (A and B). The goal was a study that resembles a typical metabolomics analysis. Here, we report our efforts and discuss challenges that create bottlenecks for the field. Finally, we discuss benchmarks that could be used by laboratories to compare their methodologies.