Evolution of the atmosphere and oceans

The residence times of most constituents of the atmosphere and oceans are small fractions of the age of the Earth and, in general, their rate of output has been nearly equal to their rate of input. We are disturbing a number of these dynamic equilibria quite severely. The mineralogy of marine evaporites rules out drastic changes in the composition of sea water during the last 900 Myr. The chemistry of soils formed more than 1,000 Myr ago suggests that the atmosphere then contained significantly more CO2 and less O2 than at present. Hydrogen peroxide may well have been the principal oxidant and formaldehyde the main reductant in rain water between 3,000 and 1,000 Myr ago. Major changes in atmospheric chemistry since that time are almost certainly related to the evolution of the biosphere.     

Secular variation in carbon isotope ratios from Upper Proterozoic successions of Svalbard and East Greenland

Analyses of stratigraphically continuous suites of samples from Upper Proterozoic sedimentary successions of East Greenland, Spitsbergen and Nordaustlandet (Svalbard) provide an approximation to the secular variation in carbon isotope ratios during a geologically and biologically important period of change from around 900 million years ago to the beginning of the Cambrian period. Late Riphean carbonates and organic material show a stratigraphically useful pattern of enrichment in 13C relative to Phanerozoic or earlier Proterozoic samples. Isotopic compositions of isolated samples from other localities are consistent with a worldwide extended interval of enhanced organic burial and consequent net survival of oxidized material, probably O2, just before the initial radiation of metazoans.     

Organically preserved microbial endoliths from the late Proterozoic of East Greenland

Diverse microorganisms ranging from cyanobacteria to eukaryotic algae and fungi live endolithically within ooids, hardgrounds and invertebrate shells on the present-day sea floor. These organisms are involved in the mechanical destruction of carbonates, and are useful ecological indicators of water depth and pollution. The Phanerozoic history of microbial endoliths has been elucidated through the study of microborings (the trace fossils of endolithic microorganisms) and rare cellularly preserved individuals, but nothing was known of the possible Precambrian evolution of comparable microorganisms until Campbell documented the occurrence of microborings in late Proterozoic ooids from central East Greenland. We now report the discovery of large populations of organically preserved endolithic microorganisms in silicified pisolites from 700-800-Myr-old Limestone-Dolomite Series of East Greenland. This fossil assemblage is significant for three reasons: (1) It confirms the prediction that oolites, pisolites and hardgrounds--the substrates for pre-Phanerozoic endoliths--provide a hitherto poorly explored but rewarding set of environments into which the search for early microfossils must be broadened; (2) the assemblage is diverse, containing about 12 taxa of morphologically distinct and previously unknown endolithic cyanobacteria, plus associated epilithic and interstitial populations; and (3) at least six of the fossil populations are indistinguishable in morphology, pattern of development, reproductive biology and inferred ecology from distinctive cyanobacterial species that bore ooids today in the Bahama Banks.     

Internalization of polypeptide hormones and receptor recycling

Conclusion The insulin receptor is an integral protein of the plasma membrane of the cell. It is composed of two subunits: an subunit, which binds the hormone, and a subunit which is a tyrosine specific protein kinase capable of undergoing autophosphorylation. These independent subunits are synthesized by way of a higher molecular weight single chain precursor and thus are the product of a single gene^{29, 49, 85} localized to chromosome 19^{29, 91}. Assuming that the insulin receptor is synthesized in the same fashion as other integral membrane glycoproteins, then the nucleus, the rough endoplasmic reticulum, and the Golgi apparatus are involved in its biosynthesis. Further, there must be some form of transport of the mature receptor subunits to the plasma membrane where they are inserted.By contrast, the endocytotic route involves coated pits, coated vesicles, large clear vesicles or endosomes, multivesicular bodies and other lysosomal forms. In addition, it is possible that some other as yet unidentified organelle is involved in recycling (fig. 8). At the present time, with respect to the insulin receptor, the biosynthetic pathway and the endocytotic pathway appear to be separate. Further, it does not appear that either pathway, i. e. synthesis or endocytosis, exerts a regulatory function over the other.     

Position of the Y-chromosome at somatic metaphase in patients with chronic myelogenous leukemia (CML)

Summary A random distribution of the Y-chromosome at somatic metaphase was found in 50 patients with Ph' positive chronic myelogenous leukemia (CML). Thus, it is concluded that the positive of the Y-chromosome at somatic metaphase does not appear to influence the loss from bone marrow cells.     

Studies on some enzymes of the toad (Bufo melanostictus) testis and their probable role at the time of fertilization

Summary Glycosidases like sialidase,-galactosidase, -L-fucosidase, N-acetyl hexosaminidase and proteases were detected in toad testis. Neuraminic acid aldolase activity was also detected. The enzyme activities were found to vary as production of spermatozoa varied. All enzymes, except N-acetyl glucosaminidase, were shown to decrease after injection of toad pituitary extract and they were also found to be absent from testis containing no spermatozoa. The glycosidases were found to act on toad oviduct jelly and they may therefore be involved in the degradation of the jelly after fertilization, into smaller bits, which may be utilized as nutrients by the fertilized zygote.Acknowledgment. We thank Prof. T.R. Ramaiah, Head of the Department of Biochemistry, University of Mysore, for his help. We also acknowledge the financial assistance of University Grants Commission to one of us (MS) and CSIR through a grant No. 9 (165)83/EMR-II to HSS. Please address all correspondence to H.S. Seshadri.     

Loss of antibody production accompanied by chromosome loss in a cloned hybrid line secreting antibodies to sheep red blood cells

Summary Somatic cell hybrids between Sp2/O-Ag14 mouse myeloma cells and lymphocytes derived from BALB/c mice hyperimmunized with sheep red blood cells (SRBC) were produced. One hybrid producing IgG₁ antibody to SRBC was selected, cloned twice and subsequently transferred to BALB/c mice. After a number of transfers it was found that the antibody titer in ascitec fluid gradually decreased. Cytogenetic analysis revealed gradual chromosome loss in the hybrid clone, which produced progressively less antibody.     

Antidiuretic effects of oxytocin in the Brattleboro rat

Summary The antidiuretic activity of oxytocin (OT) was measured in Brattleboro rats with congenital diabetes insipidus. A dose dependent antidiuretic response was found in animals receiving chronic infusions of 0.1 g/h, 1.0 g/h, and 5 g/h of OT. OT infused at the rate of 5 g/h over a 7-day period completely reversed the symptoms of diabetes insipidus. The results support the concept that OT serves as a weak agonist of vasopressin at the level of the kidney and at pharmacological levels exhibits antidiuretic activity.     

Chemical attraction of the eastern yellowjacket,Vespula maculifrons (Hymenoptera: Vespidae)

Summary Workers and queens of the eastern yellowjacket,Vespula maculifrons, are attracted to the artificial long-range attractant pheromone of the predaceous pentatomid,Podisus maculiventris. A 11 mixture of linalool or -terpineol and (E)-2-hexenal is as attractive toV. maculifrons workers as the pheromone.We thank A.S. Menke of the Systematic Entomology Laboratory, USDA, for identifying the yellowjackets. Mention of a company name does not imply endorsement by the US Department of Agriculture.     

Determination of certain physical and chemical characteristics of the activating serum factor from preparturient women and women with habitual abortions

Summary Follow-up investigation of the blood sera from preparturient women and women with habitual, abortions showed the presence of a factor which has an activating effect on smooth muscle preparations because it causes the release of prostaglandins. Gel-chromatographic counter flow separation and microelectrophoresis of the blood sera have shown that the isolated serum factor is a water soluble glycopeptide with a molecular weight of about 2000.