Reproductive phenology of a wet forest understorey in the Western Ghats, South India

The reproductive phenology of 60 understorey species was monitored at monthly intervals for 20 months in a medium elevation wet evergreen forest in the Southern Western Ghats. The life forms monitored were herbs (including terrestrial orchids), shrubs and small trees. Flowering and fruiting were non‐uniform with a dry season flowering peak and wet season fruiting peak. Flowering in the understorey correlated negatively with rainfall. No significant correlation was detected for fruiting. Life forms had flowering and fruiting peaks at different times of the year.     

A versatile tool in controlling aggregation and Ag nanoparticles assisted in vitro folding of thermally denatured zDHFR

BackgroundProteins have tendency to form inactive aggregates at higher temperatures due to thermal instability. Maintenance of thermal stability is essential to gain the protein in sufficient quantity and biologically active form during their commercial production.MethodsBL21-DE3 Rosetta E. coli cells which contains plasmid pET43.1a vector was used for producing zDHFR protein commercially. The purification of N-terminal Histidine tagged zDHFR was performed by Immobilized Metal Ion chromatography (IMAC). Investigations were performed in existence and non existence of Silver nanoparticles (AgNPs). The inactivation kinetics of zDHFR in existence and non existence of AgNPs were monitored over a range of 40–80 °C as monitored by UV–Visible absorption spectroscopy.ResultsThe protein completely lost its activity at 55 °C. Kinetics of inactivated zDHFR follows first order model in presence and absence of AgNPs. Decrease in rate constant (k) values at respective temperatures depicts that AgNPs contribute in the thermostability of the protein. AgNPs also assists in regaining the activity of zDHFR protein.ConclusionsAgNPs helps in maintaining thermostability and reducing the aggregation propensity of zDHFR protein.General significanceResult explains that AgNPs are recommended as a valuable system in enhancing the industrial production of biologically active zDHFR protein which is an important component in folate cycle and essential for survival of cells and prevents the protein from being aggregated.     

Species and tissue differences in the catabolism of S-adenosyl-L-homocysteine: A quantitative,chromatographic study

Using a rapid, quantitative high pressure liquid chromatographic (HPLC) procedure for the separation of S-adenosyl-L-homocysteine (AdoHcy) and its purinic metabolites in rat and mouse brain, kidney and liver, we found that uric acid is the principal catabolic product of AdoHcy metabolism in the liver, but that none forms in brain. Rat kidney formed about 10 times as much uric acid and half as much hypoxanthine as did mouse kidney. The HPLC procedure has been adapted to assay AdoHcy hydrolase activity which was found to be lowest in the brain and highest in the liver.     

Biological clocks help reduce the physiological conflicts in avian migrants

We present evidence from experiments on overwintering populations of two Palearctic-Indian latitudinal migratory birds, the black-headed bunting (Emberiza melanocephala) and the red-headed bunting (E. bruniceps), that the bird’s clock in interaction with day length regulates seasonal rhythms of migration and reproduction such that physiological conflict between them is reduced. Initiation and termination of the body mass and testicular cycles are separately regulated photoperiodic events. For example, under stimulatory photoperiods the response curve of body mass does not overlap with that of the testicular growth. A response-specific photoperiodism is adaptive, since gain in body mass, critical to spring migration, precedes gonadal recrudescence. Finally, migration as indicated by the night-time migratory restlessness under experimental situations (e.g., intense locomotion under caged condition-called Zugunruhe) appears to be regulated by a separate circadian oscillator.     

In vitro callus induction and regeneration studies in Withania somnifera

Callus cultures were initiated from axillary leaves, axillary shoots, hypocotyls, and root segments on Murashige and Skoog (MS) (1962) medium supplemented with 2,4-D (2 mg l⁻¹) and KN (0.2 mg l⁻¹). Shoots differentiated best from axillary shoot base callus on MS medium containing BA (2 mg l⁻¹). Regenerated shoots rooted best on MS medium containing IBA (2 mg l⁻¹) alone, and IBA (2 mg l⁻¹) with IAA (2 mg l⁻¹). Plantlets were transferred to pots containing sand and soil mixture, acclimatized in a culture room and afterwards transferred to the glasshouse. This revised version was published online in June 2006 with corrections to the Cover Date.     

Endemism and sexual systems in the evergreen tree flora of the Western Ghats, India

This study reports the endemism and sexual system in the wet evergreen tree flora of the Western Ghats. A total of 656 species from 66 families and 231 genera were listed. This included a gymnosperm family (Podocarpaceae) and a monocot family (Arecaceae). No family was endemic to the Western Ghats, but 352 species (53%) from 43 families and five genera were endemic. Nearly 35% of the families had no endemics. The largest families with endemics were Dipterocarpaceae (92%), Anacardiaceae (84%), Lauraceae (72%), Fabaceae, Rubiaceae and Myrtaceae (68%). The top five contributing families in the tree flora of the Western Ghats were Euphorbiaceae, Lauraceae, Rubiaceae, Myrtaceae and Annonaceae. The 656 species were largely hermaphrodites (57%) followed by dioecious (20%), polygamous (16%) and monoecious species (5%). The rate of dioecy reported in this study (20%) is higher than reports for Puerto Rico (18%) but lower than the Malaysian rainforest (26%). Structurally, like the Neotropical forests, most evergreen forest types of the Western Ghats could be classified into four ensembles. Yet, the Western Ghats had fewer species than other tropical and Neotropical forests. The proportion of endemics in the ensembles of the Western Ghats ranged from 34% (ensemble IV) to 14% (ensemble I).     

The shrubs of the Western Ghats (South India): floristics and status

Abstract. This study examines the understorey shrub community in a wet evergreen forest of South India. The shrub community in the evergreen forests of the Western Ghats, Eastern Ghats, Sri Lanka, South-east Asia, Neotropics, Africa and Madagascar are compared. The shrub community is richer in the Old World Tropics as compared to the Neotropics. The common families in the Old World Tropics are: Rubiaceae, Acanthaceae, Euphorbiaceae, Myrsinaceae and Annonaceae. The number of families constituting the understorey shrub community falls from forty-six (Western Ghats) to thirteen (Central Amazon). The study concludes that the evergreen forests in the Western Ghats probably have the richest understorey shrub community.
Résumé. L'étude concerne la communauté d'arbustes de sous-bois d'une forêt sempervirente du Sud de l'lnde. Les communautés d'arbustes dans les forèts sempervirentes des Ghâts Occidentaux, des Ghâts Orientaux, du Sri Lanka, du Sud-Est Asie, des Néotropiques, de l'Afrique et de Madagascar sont comparées. La communauté d'arbustes est plus riche dans le Vieux Monde Tropical que dans les Néotropiques. Les families communes dans le Vieux Monde Tropical sont; Rubiaceae, Acanthaceae, Euphorbiaceae, Myrsinaceae et Annonaceae. Le nombre de families constituant la communauté d'arbustes de sous-bois varie de 46 (Ghâts Occidentaux) à 13 (Amazonie Centrale). L'étude conclue que les forêts sempervierentes des Ghàts Occidentaux ont probablement la plus riche communauté d'arbustes de sois-bois.
Mots clés. Communauté d'arbustes de sous-bois, forêts sempervirentes, Ghâts Occidentaux, endémisme, Inde.     

Nucleosome positioning and periodicity of satellite DNA in the liver of aging rats – Nucleosome positioning and periodicity of satellite DNA

The positioning of nucleosomes has been analysed by comparing the pattern of cutting sites of a probing reagent on chromatin and naked DNA. For this purpose, high molecular weight DNA and nuclei from the liver of young (18±2 weeks) and old (100±5 weeks) Wistar male rats were digested with micrococcal nuclease (MNase) and hybridized with ³²P-labelled rat satellite DNA probe. A comparison of the ladder generated by MNase with chromatin and nuclei indicates long range organization of the satellite chromatin fiber with distinct non-random positioning of nucleosomes. However, the positioning of nucleosomes on satellite DNA does not vary with age. For studying the periodicity and subunit structure of satellite DNA, high molecular weight DNA from the liver of young and old rats were digested with different restriction enzymes. Surprisingly, no noteworthy age-related change is visible in the periodicity and subunit structural organization of the satellite DNA. These results suggest that the nucleosome positioning and the periodicity of liver satellite DNA do not vary with age.