Pushpa M. Bhargava

Sphingobacterium antarcticus sp. nov., a psychrotrophic bacterium from the soils of Schirmacher oasis, Antarctica

Two pure cultures of bacteria isolated from soil samples collected in Schirmacher Oasis, Antarctica, conformed to the definition of the genus Sphingobacterium. They differed from all of the known species of Sphingobacterium in being psychrotrophic. The G+C contents of the DNA of the two strains were found to be 39.3 and 40.3 mol%, and DNA-DNA hybridization studies indicated 7% homology with S. multivorum and S. spiritivorum. The name Sphingobacterium antarcticus sp. nov. is proposed for the two Antarctic strains. The type strain is 4BY (MTCC 675), and it has been deposited with the Microbial Type Culture Collection, Institute of Microbial Technology, Chandigarh, India.

Isolates of Arthrobacter from the soils of Schirmacher Oasis, Antarctica

SummaryThirteen isolates of bacteria from the soils of Schirmacher Oasis, Antarctica have been identified as members of the genus Arthrobacter. All the isolates exhibited a rod-coccus cycle during growth; were gram positive, catalase positive, non-motile and non-fermentative; did not form endospores; and contained MK-8 (H2) as the major menaquinone. The mole %G + C in DNA of the isolates ranged from 58% to 72%. Based on their morphology, physiology, nutritional requirements, biochemical characteristics, and mole %G + C of their DNA, the isolates were identified as A. globiformis, A. pascens and A. protophormiae. However, unlike the mesophilic isolates the Antarctic Arthrobacter could be considered to be unique as they were psychrotrophic, contained glucose and lysine in the cell wall, and did not hydrolyze starch.

Isolation and identification ofMicrococcus roseus andPlanococcus sp. from schirmacher oasis, antarctica

Five cultures isolated from soil samples collected in Schirmacher oasis, Antarctica, have been identified as members of the familyMicrococcaceae, with 3 belonging to the genusMicrococcus and two toPlanococcus. The 3Micrococcus isolates (37R, 45R and 49R) were red-pigmented and h a d ∼ 75 mol% G + C in their DNA; they were identified asMicrococcus roseus. The twoPlanococcus isolates (30Y and Lz3OR) were yellow and orange in colour, and had 43.5 and 40.9 mol % G + C in their DNA respectively; they were identified asPlanococcus sp.

Yeast strains from the Schirmacher Oasis, Antarctica

SummarySoil samples from the Schirmacher Oasis of Antarctica were examined for the presence of yeasts. The number of yeast cells in the samples varied between 600 and 3000 g of wet soil. Eight pure cultures were obtained. All of the eight isolates were nonfermentative and all but one was Diazonium Blue B (DBB)-positive, indicating their basidiomycetous affinity. Based on their morphology, reproductive behavior, growth at different temperatures and salt concentrations, nutritional characteristies and various biochemical tests, all the eight cultures have been identified. Three of them are red yeasts, Rhodotorula rubra, one Bullera alba, one a dimorphic, Candida humicola and one Candida famata. The remaining two cultures have been tentatively identified as Candida ingeniosa and Candida auriculariae.

A new pyrimidine-specific ribonuclease from bovine seminal plasma that is active on both single and double-stranded polyribonucleotides and that can distinguish between Mg2+-containing and Mg2+-depleted naturally occurring RNAs.

The purification to homogeneity of a new ribonuclease, named RNAase SPL, from bovine seminal plasma is described. This nuclease, like the bovine pancreatic RNAase A, is pyrimidine specific. Its activity on single-stranded synthetic polyribonucleotides such as poly(rU) is significantly higher than that of RNAase A. However, unlike RNAase A, RNAase SPL is highly active on a double-stranded RNA such as poly[r(A · U)], and shows extremely limited activity on naturally occurring RNAs, such as Escherichia coli RNA, prepared with Mg2+ present throughout the isolation procedure. Under conditions of limiting hydrolysis in which RNAase A degrades 60 to 90% of total E. coli RNA to acid-soluble material and the remaining to material having a molecular weight lower than that of transfer RNA, RNAase SPL does not yield any acid-soluble products: it does not appear to degrade tRNA or 5 S RNA, and causes only a small number of nicks in the remaining RNAs to yield a limiting digest containing products with molecular weights ranging between 10,000 and 150,000. Absence of Mg2+ during the isolation procedure, or heat denaturation of the RNA makes it as susceptible to RNAase SPL as it is to RNAase A. The above and other related observations reported here support the view that there are Mg2+-dependent structural features, besides single and doublestrandedness, in naturally occurring RNAs, that can be distinguished by using the two nucleases RNAase SPL and RNAase A.

Bacteriolytic Activity of Seminalplasmin

Seminalplasmin, an antimicrobial protein from bovine seminal plasma, lysed both Gram-positive and Gram-negative bacteria but not Candida albicans. The lytic activity was not lysozyme-like and was not affected by inhibitors of RNA or protein synthesis or by azide; it was strongly inhibited by divalent cations like Ca2+, Mn2+ and Mg2+ at millimolar concentrations. Maximum lysis of Escherichia coli was obtained at 37 degrees C; heat treatment of E. coli drastically reduced its susceptibility to lysis by seminalplasmin. E. coli cells in the stationary phase of growth were lysed much less than those in the exponential phase, and those grown in an enriched medium were lysed much more than those grown in a minimal medium. It appears that the lytic activity of seminalplasmin is due to the activation of an autolysin.

Isolation and characterization of autolysis-defective mutants of Escherichia coli that are resistant to the lytic activity of seminalplasmin.

Two temperature-sensitive autolysis-defective mutants of Escherichia coli were isolated and shown to be resistant to lysis induced by seminalplasmin, an antimicrobial protein from bovine seminal plasma, as well as to lysis induced by ampicillin, D-cycloserine and nocardicin, at 37 or 42 degrees C but not at 30 degrees C. The mutants were, however, sensitive to inhibition of RNA synthesis by seminalplasmin even at the nonpermissive temperature. Temperature-resistant revertants of the mutants were sensitive to lysis induced by the various antibiotics at 37 or 42 degrees C. The mutations in both strains were mapped at 58 min on the E. coli linkage map. The lysis resistance of the mutants was phenotypically suppressed by the addition of NaCl. Partial suppression of the lysis-resistant phenotype was also observed in a relA genetic background.

The minimum requirements for the evolution of a cell

Most scientists would agree that chemical evolution has occurred on our planet after its formation some 4.5 billion years ago. During this evolution, increasingly complex substances (including polyribonucleotides and polypeptides), in increasing variety, were formed as time progressed, from the simpler chemical constituents of Earth’s primordial atmosphere, aided by climatic and geological changes. The evidence for this comes from laboratory experiments simulating conditions that are likely to have been prevalent in the Earth’s earliest atmosphere, and from the analysis of carbon-containing compounds in meteorites, comets and interstellar space. It seems most likely that chemical evolution would be an inevitable outcome on any planet on which conditions similar to those on Earth when it was formed, would exist.

Regulation of cell division and malignant transformation.

The problem of regulation of cell division is essentially a problem of understanding regulation of transition from the resting state of a cell to the dividing state and vice versa. In malignancy the ability to revert back to a normal resting state is impaired. A model is presented which attempts to explain the control of the above transitions through control of uptake of essential nutrients by a transport-inhibitory protein. Experimental evidence in favour of the model is given.

Biotechnology in India: The beginnings

India has a well-documented tradition of science and technology spanning five millennia. Even though there have been ups and downs – golden periods and dark ages – the tradition has had a thread of continuity. Otherwise the Royal Society of Britain would not have elected A. Cursetjee working in the Mazgaon docks of the then Bombay city as its first Indian Fellow as far back as 1841 for his expertise in marine engineering and naval architecture from which the British benefited substantially. Few countries in the world have some 5000 years of documented political, social and scientific history. It is widely recognized that until about 500 years ago – in some areas such as naval architecture, agriculture and number theory, until a hundred years ago – India was a world leader. And our successes in science and technology covered a vast range that included mathematics, astronomy, chemistry, medicine, anatomy, surgery, botany, zoology, metallurgy and perfumery. In biology, our successes were specially remarkable [1]. Thus, the basic human anatomy including every bone in the human body that we know today, the process of digestion, the entire sequence of fetal development week by week, the classification of plants and animals, the internal structure of a leaf, the recognition of the six basic tastes (sweet, sour, salty, pungent, bitter and astringent), understanding of many diseases including those like small pox that were spread by agents that were invisible to the naked eye, the mechanism of human reproduction, the principles of nutrition, circulation of blood, and certain principles of heredity, were reasonably well understood in ancient and medieval India. In fact, the widely-held impression that all of India was in a state of a decline in the late 18th century when the British acquired dominance over the country, is argued against by the fact that inoculation against small pox was practiced in the subcontinent before it became generally acceptable in Europe. In 1720, the wife of the then British Ambassador in Turkey got her children successfully inoculated against small pox using the indigenous Indian technique, which led to the introduction of the technique into Britain. There were primarily three reasons for our successes in science and technology in the ancient and medieval periods: (a) our ability to observe accurately and record our observations faithfully; (b) draw inferences and establish correlations on the basis of the observations made; and (c) learn from trial and error. Indeed, our ancestors must have been compulsive observers, so much so that nothing that could have been observed with the naked eye ever seems to have escaped their notice. Somewhere on the way, perhaps during the last half century, we have, as a nation, lost this quality to our great disadvantage. This is not to say that Indian science, including biology, has not had its failures in ancient and medieval India.All through those periods of our history, untruths had been perpetuated and scientific progress retarded in the Indian subcontinent for the following reasons. India Biotech Highlight