In vitro propagation of Lagerstromia parviflora Roxb. from adult tree

A micropropagation protocol based on axillary bud proliferation has been developed from mature Lagerstromia parviflora adult tree. Nodal segments cultured on woody plant medium supplemented with 5.0 microl. BAP and 0.25 microm IAA gave maximum (86.9%) morphogenetic response. Proliferated shoots (10.7 per explants) were elongated to 3.9 cm within 6 weeks. In vitro produced micro-shoots were subjected to an IBA treatment (500 ppm for 2 min. dip) and placed under misting conditions for rooting. Misting beds were prepared with sand: soil (3:1) for 80.6% rooting and was acclimatized. Shoot length seems to be important to induce adventitious roots. The highest (91.7%) rooting was recorded on shoots ranging a length between 3.1-4.0 cm. Rooted and hardened plants were later transferred to poly bags and maintained in shadenet house. The protocol has the realizes capacity to produce 260 plants from a single explants within 10 months multiplication cycle.     

Molecular Phylogenetic Exploration of Bacterial Diversity in a Bakreshwar (India) Hot Spring and Culture of Shewanella-Related Thermophiles

The bacterial diversity of a hot spring in Bakreshwar, India, was investigated by a culture-independent approach. 16S ribosomal DNA clones derived from the sediment samples were found to be associated with gamma-Proteobacteria, cyanobacteria, and green nonsulfur and low-GC gram-positive bacteria. The first of the above phylotypes cobranches with Shewanella, a well-known iron reducer. This phylogenetic correlation has been exploited to develop culture conditions for thermophilic iron-reducing microorganisms.     

Flotation characteristics of cyanobacterium Anabaena flos-aquae for gas vesicle production

Cyanobacterium Anabaena flos-aquae was cultivated in photobioreactors for production of intracellular gas vesicles (GVs), as potential oxygen microcarriers. Natural flotation of the buoyant culture was investigated as a potential means of cell harvesting, because filtration and centrifugation tended to destroy the vesicles. Best flotation was found with actively growing culture and when conducted in the dark. The flotation-related cell properties, including the specific GV content, vesicle-collapsed filament density, and intracellular carbohydrate content, were measured to understand the phenomena. During the batch culture, the specific GV content remained relatively constant at 370 microL/(g dry cells) but the filament density (ranging 1.02 to 1.08 g/cm3) showed a decrease-then-increase profile. The increase began when the growth slowed down because of the reduced light availability at high cell concentrations. The dark flotation was studied with both actively growing (mu approximately 0.2 day-1) and stationary-phase cultures. The specific GV content of the stationary-phase culture remained relatively constant while that of the growing culture increased slightly. The intracellular carbohydrate content of the growing culture decreased much faster and more significantly, from 57 to 10 mg/(g dry cells) in 相似文献   

Autoprotection: Stimulated tissue repair permits recovery from injury

Autoprotection is a phenomenon whereby prior exposure to a small dose of a chemical results in protection against a subsequently administered lethal dose of the same compound. While CCl₄ autoprotection has been studied the most, it has also been demonstrated for other chemicals. Recent studies indicate that the prevailing concept of decreased bioactivation of the normally lethal dose of CCl₄ owing to decreased hepatic microsomal cytochrome P-450

1 Abbreviations used: CD, chlordecone; cyt. P-450, cytochromes P-450; M, mirex; N, normal diet; PB, phenobarbital.

content can not be supported by direct end points of liver injury such as necrosis. These findings suggest a pivotal role for hepatocellular division and tissue healing processes stimulated by the protective dose in the mechanism of autoprotection. Augmentation of hepatocellular regeneration and tissue repair, stimulated by the protective dose, appears to permit timely recovery and restoration of hepatic structure and function. In the absence of the protective dose, hepatocellular division is substantially deficient and it occurs too late to tip the delicate balance between recovery from injury and progression of massive injury in favor of recovery. Abolition of autoprotection by colchicine antimitosis, under conditions where metabolism and disposition of CCl₄ are not altered, is supportive of this concept. Selective colchicine antimitotic suppression of the early phase of hepatocellular division and tissue repair induced by a low dose of CCl₄ results in progression of toxic liver injury, leading to hepatic failure and mortality. Studies have shown that pretreatment with phenobarbital results in postponed low-dose CCl₄-stimulated cell division by 24 hours, which accordingly postpones the optimal autoprotection. These findings provide discrete evidence to suggest that the protective dose-stimulated hepatocellular division and tissue repair underlies the mechanism of autoprotection. These new insights reveal that in contrast to the widely held concept, the ultimate outcome of toxic injury is determined by whether a prompt stimulation of sustainable tissue repair can occur rather than by the magnitude of the injury inflicted by a toxic chemical.     

An assessment of biopotential of three cyanobacterial isolates from Antarctic for carotenoid production

Specific growth rates and carotenoid contents of three Antarctic and tropical strains of cyanobacteria viz. Anabaena sp., Phormidium sp. and Nostoc sp. were compared in batch and mass cultures to assess bio-potential of Antarctic strains for cost-effective carotenoid production. Antarctic strains though exhibited slightly lower specific growth rates, but contained higher carotenoid contents (per unit dry wt.), than tropical strains. Modification of normal composition of BG-11 culture medium, by altering nitrogen and carbon sources resulted in 25-38% increase in carotenoid content in both types of strains. Mass-culture in indoor and semi-outdoor bio-reactors resulted in 39-113% higher carotenoid content in Antarctic strains, compared to their respective tropical strains. The observations suggest that Antarctic cyanobacteria may have potential as superior strains for maximizing the yield of carotenoids.     

A metabolomic view of how the human gut microbiota impacts the host metabolome using humanized and gnotobiotic mice

Defining the functional status of host-associated microbial ecosystems has proven challenging owing to the vast number of predicted genes within the microbiome and relatively poor understanding of community dynamics and community–host interaction. Metabolomic approaches, in which a large number of small molecule metabolites can be defined in a biological sample, offer a promising avenue to ‘fingerprint'' microbiota functional status. Here, we examined the effects of the human gut microbiota on the fecal and urinary metabolome of a humanized (HUM) mouse using an optimized ultra performance liquid chromatography–mass spectrometry-based method. Differences between HUM and conventional mouse urine and fecal metabolomic profiles support host-specific aspects of the microbiota''s metabolomic contribution, consistent with distinct microbial compositions. Comparison of microbiota composition and metabolome of mice humanized with different human donors revealed that the vast majority of metabolomic features observed in donor samples are produced in the corresponding HUM mice, and individual-specific features suggest ‘personalized'' aspects of functionality can be reconstituted in mice. Feeding the mice a defined, custom diet resulted in modification of the metabolite signatures, illustrating that host diet provides an avenue for altering gut microbiota functionality, which in turn can be monitored via metabolomics. Using a defined model microbiota consisting of one or two species, we show that simplified communities can drive major changes in the host metabolomic profile. Our results demonstrate that metabolomics constitutes a powerful avenue for functional characterization of the intestinal microbiota and its interaction with the host.