Nucleolus size varies with sex,ploidy and gene dosage in insects

The nucleolus constitutes a cytologically visible phenotype for ribosomal DNA (rDNA). Nucleolar size, as determined by silver staining, is a good indicator of cell proliferation rate and biosynthetic activity. Nevertheless, the relationship between rDNA content and sexual dimorphism for nucleolar size is not well documented. In the present study, the impact of sex and ploidy level on nucleolar size is investigated in three haplo/diploid and three diplo/diploid species of insect. Nucleolar sizes are found to be proportional to ploidy level in the haplo/diploid hymenopterans Trypoxylon albitarse and Nasonia vitripennis. Conversely, in the ant Messor barbarus, nucleolar sizes are larger in haploid males (winged) than diploid females (apterous). Among the diplo/diploid species, evidence for gene dosage compensation on nucleolar activity is suggested by the absence of sex differences in Drosophila simulans, a species in which rDNA is limited to the X chromosome. By contrast, in the grasshopper Stenobothrus festivus, another species with rRNA genes restricted to the X chromosome, the size of the nucleolus is significantly larger in females than in males. Additionally, in the grasshopper Chorthippus parallelus, where rDNA is distributed evenly on several autosomes of males and females, the females also show larger nucleoli than males. In both grasshopper species, the magnitude of the female/male ratio for nucleolus area is very similar to the body size ratio, suggesting that body size, as well as sex, ploidy, gene dosage and physiological activity, may be an important determinant of nucleolus area.     

31P NMR of phospholipid glycerol phosphodiester residues

Saponification of extracted tissue phospholipids yields a set of isolated glycerol 3-phosphoryl phospholipid polar headgroups from which semi-quantitative 31P NMR spectra can be obtained. The resonance signals from these molecules, which frequently have been reported as uncharacterized phosphate signals observed in perchloric acid extracts of tissue, can be used as an aid in the characterization of isolated phospholipids and of tissue phospholipid 31P NMR profiles. 31P NMR chemical-shift values of the resonances at pH 7 in water and relative to 85% phosphoric acid are: glycerol 3-phosphocholine (-0.13 delta), glycerol 3-phosphoethanolamine (0.42 delta), glycerol 3-phospho(monomethyl)ethanolamine (0.29 delta), glycerol 3-phospho(dimethyl)ethanolamine (0.16 delta), glycerol 3-phosphoserine (0.14 delta), glycerol 3-phosphoinositol (-0.07 delta), glycerol 3-phosphoglycerol (0.92 delta), bis(glycerol 3-phospho)glycerol (0.79 delta), serine ethanolamine phosphodiester (-0.46 delta), glycerol 3-phosphate (0.60 delta; 4.29 delta at pH 10) glycerol 2-phosphate (0.15 delta; 3.92 delta at pH 10). In addition, analysis of extracted cancer tissue phospholipid samples yielded a new and uncharacterized polar headgroup fragment with a chemical-shift value of 0.29 delta that is independent of sample pH.     

Differential protein expression in alligator leukocytes in response to bacterial lipopolysaccharide injection

Blood was collected from three juvenile alligators (Alligator mississippiensis) before, and again 24 h after, injection with bacterial lipopolysaccharide (LPS). The leukocytes were collected from both samples, and the proteins were extracted. Each group of proteins was labeled with a different fluorescent dye and the differences in protein expression were analyzed by two dimensional differential in-gel expressions (2D-DIGE). The proteins which appeared to be increased or decreased by treatment with LPS were selected and analyzed by MALDI-TOF to determine mass and LC–MS/MS to acquire the partial protein sequences. The peptide sequences were compared to the NCBI protein sequence database to determine homology with other sequences from other species. Several proteins of interest appeared to be increased upon LPS stimulation. Proteins with homology to human transgelin-2, fish glucose-6-phosphate dehydrogenase, amphibian α-enolase, alligator lactate dehydrogenase, fish ubiquitin-activating enzyme, and fungal β-tubulin were also increased after LPS injection. Proteins with homology to fish vimentin 4, murine heterogeneous nuclear ribonucleoprotein A3, and avian calreticulin were found to be decreased in response to LPS. In addition, five proteins, four of which were up-regulated (827, 560, 512, and 650%) and one that exhibited repressed expression (307%), did not show homology to any protein in the database, and thus may represent newly discovered proteins. We are using this biochemical approach to isolate and characterize alligator proteins with potential relevant immune function.     

Ultrastructural and autoradiographic observations of hamster cheek pouch epithelium grown in vitro

Summary Epithelial outgrowths from hamster cheek pouch explants were cultured for varying peroids of time up to 22 days. Growth of the epithelial sheets was monitored, employing colcemid for demonstrating mitotic activity and tritiated thymidine for DNA synthesis. Mitoses and thymidine uptake were observed among epithelial outgrowths at a considerable distance from the original explant. The epithelial nature of the growing cell sheets was confirmed, employing electron microscopic techniques. The cells exhibited the presence of tonofilaments, desmosomes, ribosomes, Golgi, mitochondria, and rough endoplasmic reticulum. The cultured explants were treated with cyclic nucleotides in order to investigate their modulatory effects on epithelial cell differentiation. Dibutyryl cAMP induced marked mitotic inhibition (46.3%) in our assay, which was increased to 57% with the addition of theophylline. Dibutyryl cGMP showed only a mild (5%) stimulatory effect on mitotic activity. Dibutyryl cAMP enhanced keratinization in the epithelial cell out-growths with the biogenesis of keratohyalin granules, whereas dibutyryl cGMP did not produce any observable alterations.     

Biochemical and physiological impacts of zinc sulphate,potassium phosphite and hydrogen sulphide in mitigating stress conditions in soybean

Soybean is the most widely grown oilseed in the world. It is an important source of protein and oil which are derived from its seeds. Drought stress is a major constraint to soybean yields. Finding alternative methods to mitigate the water stress for soybean is useful to maintain adequate crop yields. The aim of this study was to evaluate the morpho-physiological, biochemical and metabolic changes in soybean plants in two ontogenetic stages, under exposure to water deficit and treatment with zinc sulphate (ZS), potassium phosphite (PP) or hydrogen sulphide (HS). We carried out two independent experiments in the V4 and R1 development stages consisting of the following treatments: well-watered control (WW, 100% maximum water holding capacity, MWHC), water deficit (WD, 50% MWHC), PP + WW, PP + WD, HS + WW, HS + WD, ZS + WW and ZS + WD. The experimental design consisted of randomized blocks with eight treatments with five replicates. Morphological, physiological and metabolic analyses were performed 8 days after the start of the treatments for both experiments. We identified two tolerance mechanisms acting in response to compound application during water stress: the first involved the upregulation of antioxidant enzyme activity and the second involved the accumulation of soluble sugars, free amino acids and proline to facilitate osmotic adjustment. Both mechanisms are related to the maintenance of the photosynthetic parameters and cell membrane integrity. This report suggests the potential agricultural use of these compounds to mitigate drought effects in soybean plants.     

Spring phenology in boreal Eurasia over a nearly century time scale

It has been widely reported that tree leaves have tended to appear earlier in many regions of the northern hemisphere in the last few decades, reflecting climate warming. Satellite observations revealed an 8-day advance in leaf appearance date between 1982 and 1991 in northern latitudes. In situ observations show that leaf appearance dates in Europe have advanced by an average of 6.3 days from 1959 to 1996. Modelling of leaf appearance on the basis of temperature also shows a marked advance in temperate and boreal regions from 1955 to 2002. However, before 1955, reported studies of phenological variations are restricted to local scale. Modelling, ground observations and satellite observations are here combined to analyse phenological variations in Eurasian taiga over nearly a century. The trend observed by remote sensing consists mainly in a shift at the end of the 1980s, reflecting a shift in winter and spring temperature. In western boreal Eurasia, a trend to earlier leaf appearance is evident since the mid-1930s, although it is discontinuous. In contrast, the strong advance in leaf appearance detected over Central Siberia using satellite data in 1982–1991 is strengthened by late springs in 1983–1984; moreover, in this region the green-up timing has displayed successive trends with opposite signs since 1920. Thus, such strong trend is not unusual if considered locally. However, the recent advance is unique in simultaneously affecting most of the Eurasian taiga, the leaf appearance dates after 1990 being the earliest in nearly a century in most of the area.