Rain forest expansion mediated by successional processes in vegetation thickets in the Western Ghats of India

Aim The objective of this study was to document succession from grassland thickets to rain forest, and to provide evidence for their potential as restoration tools. Location The Linganamakki region (State of Karnataka) of the Central Western Ghats of India. Method We selected thirty vegetation thickets ranging from 4 to 439 m² in area in the vicinity of rain forest. The area of each small thicket was estimated as an oval using its maximum length and its maximum width. When the shape was irregular (mostly in large thickets) the limits of the thicket were mapped and the area calculated from the map. Plant species were identified, the number of individuals was estimated and their heights measured. Results There was a progression in the thickets from early to late successional species. Small thickets were characterized by ecotone species and savanna trees such as Catunaregam dumetorum. Savanna trees served as a nucleus for thicket formation. Colonizing species were mostly bird‐dispersed. As succession proceeded in larger thickets, the proportion of evergreen, late‐successional rain forest trees increased. The species composition of the large thickets differed depending on the species composition of reproductive adults in the nearby forested areas. The species within small thickets were also found in the large thickets. The nestedness in species composition suggested that species turnover was deterministic based on thicket size. Human disturbance (leaf and wood collection by the local populations) affected the species composition and the species–area relationship of thickets. Main conclusions Vegetation thickets are nodal centres for rain forest colonization within grasslands. They expand and replace savanna. Early successional bird‐dispersed species established around savanna trees followed by late‐successional rain forest trees dispersed from the nearby forest by birds. Restoration programmes that reproduce natural successional processes such as those observed in thickets will be more successful and less expensive than the methods currently being employed, where trees are individually planted in grassland. Wood harvesting is the only factor that prevents thicket growth and coalescence and hampers forest expansion.     

Cutaneous Phaeohyphomycosis due to Alternaria Infectoria

Here we report a case of cutaneous alternariosis in a 74-year-old man treated by corticotherapy for myasthenia, and presenting with papular, crusted lesions on the left elbow and the right knee. Histological examination of the biopsy specimens showed fungal hyphae associated with round-shaped cells which were highly suggestive of alternariosis. Mycological culture allowed the isolation of a dematiaceous fungus which was identified as a member of the Alternaria infectoria species-group. This was confirmed by PCR amplification and sequencing of the internal transcribed spacer domain of the gene encoding nuclear ribosomal DNA and of the mitochondrial small subunit ribosomal DNA domain. The fungus was therefore referred to the Scientific Institute of Public Health where it was identified as Alternaria infectoria, on the basis of its very small 1 or 2-celled conidia often arranged in long chains and presenting with very long secondary conidiophores. Corticotherapy was stopped and a local antifungal treatment with ketoconazole was initiated, allowing the stabilisation of the cutaneous lesions within 2 months.     

Hepatic triglyceride contents are genetically determined in mice: results of a strain survey

To assess whether genetic factor(s) determine liver triglyceride (TG) levels, a 10-mouse strain survey of liver TG contents was performed. Hepatic TG contents were highest in BALB/cByJ, medium in C57BL/6J, and lowest in SWR/J in both genders. Ninety and seventy-six percent of variance in hepatic TG in males and females, respectively, was due to strain (genetic) effects. To understand the physiological/biochemical basis for differences in hepatic TG among the three strains, studies were performed in males of the BALB/cByJ, C57BL/6J, and SWR/J strains. In vivo hepatic fatty acid (FA) synthesis rates and hepatic TG secretion rates ranked BALB/cByJ approximately C57BL/6J > SWR/J. Hepatic 1-(14)C-labeled palmitate oxidation rates and plasma beta-hydroxybutyrate concentrations ranked in reverse order: SWR/J > BALB/cByJ approximately C57BL/6J. After 14 h of fasting, plasma-free FA and hepatic TG contents rose most in BALB/cByJ and least in SWR/J. beta-Hydroxybutyrate concentrations rose least in BALB/cByJ and most in SWR/J. Adaptation to fasting was most effective in SWR/J and least in BALB/cByJ, perhaps because BALB/cByJ are known to be deficient in SCAD, a short-chain FA oxidizing enzyme. To assess the role of insulin action, glucose tolerance test (GTT) was performed. GTT-glucose levels ranked C57BL/6J > BALB/cByJ approximately SWR/J. Thus strain-dependent (genetic) factors play a major role in setting hepatic TG levels in mice. Processes such as FA production and hepatic export in VLDL on the one hand and FA oxidation on the other, explain some of the strain-related differences in hepatic TG contents. Additional factor(s) in the development of fatty liver in BALB/cByJ remain to be demonstrated.     

Development of an efficient strategy for the synthesis of the ETB receptor antagonist BQ-788 and some related analogues

BQ-788 [N-cis-2,6-dimethylpiperidine-1-carbonyl-L-gamma-methylleucyl-D-1-methoxycarbonyltryptophanyl-D-norleucine sodium salt] is a very potent and selective ETB receptor antagonist. The formation of the highly hindered trisubstituted urea functionality in the peptide chain and the carbamination on the indole nitrogen of the tryptophan side chain are major challenges in the synthesis of this particular antagonist. Furthermore, the high cost of the unnatural amino acids in the sequence of BQ-788 and its reported synthesis render this pseudopeptide very expensive to produce. In order to improve the yield and to reduce the number of steps compared to previous reported syntheses, we developed an efficient strategy involving a novel one-pot procedure for the synthesis of a highly hindered trisubstituted urea. Under very mild conditions, the urea was obtained by using triphosgene and sodium iodide. This strategy allowed us to synthesize BQ-788 in seven steps with an overall yield of 53%. We also generalized the use of this powerful methodology by creating some new structural analogues of the cis-2,6-dimethylpiperidine moiety by replacing it with other bulky secondary amines. We evaluated the antagonist properties of those three new analogues of BQ-788 in two bioassays in vitro. These new antagonists were less potent than BQ-788 in an ETB rich preparation and inactive in an ETA rich preparation.     

Relationship between allelic state of T-DNA and DNA methylation of chromosomal integration region in transformed <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> plants

T-DNA insertions are currently used as a tool to introduce, or knock out, specific genes. The expression of the inserted gene is frequently haphazard and up to now, it was proposed that transgene expression depends on the site of insertion within the genome, as well as the number of copies of the transgene. In this paper, we show that the allelic state of a T-DNA insertion can be at the origin of epigenetic silencing. A T-DNA insertional mutant was characterized to explore the function of AtBP80a′, a vacuolar sorting receptor previously associated with germination. Seeds homozygous for the T-DNA do not germinate, but this can be overcome by a cold treatment and maintained by the following generations. The non-germinating phenotype is only observed in homozygous seed produced by heterozygous plants indicating that it is correlated with the allelic state of the T-DNA in parental lines. Analysis of the region between the T-DNA insertion and the ATG codon of atbp80a′ showed that cytosine methylation is highly enhanced in chromatin containing the T-DNA. Data presented here show that an unpaired DNA region during meiosis could be at the origin of a de novo cytosine methylation mechanism.     

Ablation of PRC1 by small interfering RNA demonstrates that cytokinetic abscission requires a central spindle bundle in mammalian cells, whereas completion of furrowing does not

The temporal and spatial regulation of cytokinesis requires an interaction between the anaphase mitotic spindle and the cell cortex. However, the relative roles of the spindle asters or the central spindle bundle are not clear in mammalian cells. The central spindle normally serves as a platform to localize key regulators of cell cleavage, including passenger proteins. Using time-lapse and immunofluorescence analysis, we have addressed the consequences of eliminating the central spindle by ablation of PRC1, a microtubule bundling protein that is critical to the formation of the central spindle. Without a central spindle, the asters guide the equatorial cortical accumulation of anillin and actin, and of the passenger proteins, which organize into a subcortical ring in anaphase. Furrowing goes to completion, but abscission to create two daughter cells fails. We conclude the central spindle bundle is required for abscission but not for furrowing in mammalian cells.     

A memory-efficient algorithm for multiple sequence alignment with constraints

MOTIVATION: Recently, the concept of the constrained sequence alignment was proposed to incorporate the knowledge of biologists about structures/functionalities/consensuses of their datasets into sequence alignment such that the user-specified residues/nucleotides are aligned together in the computed alignment. The currently developed programs use the so-called progressive approach to efficiently obtain a constrained alignment of several sequences. However, the kernels of these programs, the dynamic programming algorithms for computing an optimal constrained alignment between two sequences, run in (gamman2) memory, where gamma is the number of the constraints and n is the maximum of the lengths of sequences. As a result, such a high memory requirement limits the overall programs to align short sequences only. RESULTS: We adopt the divide-and-conquer approach to design a memory-efficient algorithm for computing an optimal constrained alignment between two sequences, which greatly reduces the memory requirement of the dynamic programming approaches at the expense of a small constant factor in CPU time. This new algorithm consumes only O(alphan) space, where alpha is the sum of the lengths of constraints and usually alpha < n in practical applications. Based on this algorithm, we have developed a memory-efficient tool for multiple sequence alignment with constraints. AVAILABILITY: http://genome.life.nctu.edu.tw/MUSICME.