Metabolic machinery encrypted in the Raman spectrum of influenza A virus-inoculated mammalian cells

Raman spectroscopy was applied with a high spectral resolution to a structural study of Influenza (type A) virus before and after its inoculation into Madin–Darby canine kidney cells. This study exploits the fact that the major virus and cell constituents, namely DNA/RNA, lipid, and protein molecules, exhibit peculiar fingerprints in the Raman spectrum, which clearly differed between cells and viruses, as well as before and after virus inoculation into cells. These vibrational features, which allowed us to discuss viral assembly, membrane lipid evolution, and nucleoprotein interactions of the virus with the host cells, reflected the ability of the virus to alter host cells’ pathways to enhance its replication efficiency. Upon comparing Raman signals from the host cells before and after virus inoculation, we were also able to discuss in detail cell metabolic reactions against the presence of the virus in terms of compositional variations of lipid species, the formation of fatty acids, dephosphorylation of high-energy adenosine triphosphate molecules, and enzymatic hydrolysis of the hemagglutinin glycoprotein.     

Symbiotic Crab Sestrostoma balssi (Shen, 1932) (Varunidae: Gaeticinae) from Vostok Bay, Sea of Japan: A New Species for the Fauna of Russia

A symbiotic crab Sestrostoma balssi (Shen, 1932) (Varunidae: Gaeticinae) that lives in burrows of the large ghost shrimp Upogebia major (De Haan, 1841) and U. issaeffi (Balss, 1913) (Upogebiidae) was found in Vostok Bay (Peter the Great Bay, Sea of Japan) for the first time. The occurrence of mature and juvenile specimens indicates the existence of a stable population of this species in the investigated region. This finding substantially extends the distribution area of S. balssi in the Sea of Japan.     

Density-dependent regulation of growth in somatic hybrids between normal Chinese hamster fibroblasts and V79-8 (G1) cells

The purpose of this work was to determine the relationship between the presence of a G1 period in the mitotic cycle and a cell's ability to respond to density-dependent regulation of growth (DDR). Somatic hybrids were obtained between normal fibroblasts from newborn Chinese hamsters, which show a strong response to DDR, and V79-8 Chinese hamster cells, which are insensitive to DDR. Two variant V79-8 sublines were used, one reported to lack a G1 period (G1-) and the other with a G1 period (G1+). Fourteen hybrid clones were isolated in selective medium and analysed for growth properties and cell cycle parameters; their hybrid nature was supported by chromosome counts. All hybrid clones, irrespective of whether a V79-8 G1- or G1+ cell was one of the parents, showed pronounced DDR and had G1 periods of various lengths. Previous experiments had shown the absence of G1 to be dominant in somatic hybrids between V79-8 G1- and G1+ cell lines. Our results may mean that the G1- property provided by V79-8 is unable to overcome the very long G1 of normal fibroblasts, or in cells that can be arrested in G1 in response to DDR, some function prevents the dominant effect of the G1- cell on at least part of the G1 period.     

DNA PROBES AND A RECEPTOR-BINDING ASSAY FOR DETECTION OF PSEUDO-NITZSCHIA (BACILLARIOPHYCEAE) SPECIES AND DOMOIC ACID ACTIVITY IN CULTURED AND NATURAL SAMPLES

Large-subunit ribosomal RNA-targeted probes for Pseudo-nitzschia australis Frenguelli, P. multiseries (Hasle) Hasle, P. pseudodelicatissima (Hasle) Hasle, and P. pungens (Grunow) Hasle were applied to cultured and natural samples using whole-cell and sandwich hybridization. Testing of the latter method is emphasized here, and technique refinements that took place during 1996–1997 are documented. Application of the sandwich hybridization test showed that the signal intensity obtained for a given number of target cells remained constant as batch cultures of these organisms progressed from active through stationary growth phases. This suggests that cellular rRNA content for each target species remained relatively stable despite changes in growth state. Application of whole-cell and sandwich hybridization assays to natural samples showed that both methods could be used to detect wild P. australis, P. pseudodelicatissima, and to a lesser degree P. multiseries, but detection of P. pungens was prone to error. A receptor-binding assay for domoic acid (DA) enabled detection of this toxin activity associated with a particulate fraction of the plankton and provided a context in which to view results of the rRNA probe tests. In one case, the probe for P. australis cross-reacted with P. cf. delicatissima. The sample that contained the latter species also contained a low amount of DA activity. Under certain field conditions, results of whole-cell and sandwich hybridization tests disagreed. Detailed analysis of selected field samples illustrates how such situations arose. Collectively, the rRNA probe and toxin analyses suggest that manifestation of DA in the environment is possible in the absence of readily recognizable intact cells.     

Centrosome competition: a possibility?

A recent theory on the evolution of sexuality, has hypothesized heritable variation in the functional properties of centrosomes, leading to competition for the organization of the mitotic spindle when different centrosomes enter a common cytoplasm. We present here data on polyethylene glycol-induced polykaryocytes of cultured Chinese hamster fibroblasts indirectly supporting centrosome competition. On the assumption that sib centrosomes are similar and variation increases with cell generations, the frequencies of multipolar mitoses were compared in cultures fused under conditions favoring sib cell fusion or fusion of distantly related cells. Multipolar mitoses were considerably more frequent in the former, when the average difference between pairs of centrosomes was assumed to be too small for one centrosome to "outcompete" the other.