INTRACELLULAR LOCALIZATION OF THE TASTE/ODOR METABOLITE 2-METHYLISOBORNEOL IN OSCILLATORIA LIMOSA (CYANOPHYTA)1

The monoterpene derivative, 2-methylisoborneol (MIB), is produced by many blue-green algae and often is responsible for the “musty” taste/odor in aquaculturally raised finfish and potable water supplies. Although previous researchers have suggested that taste/odor metabolites are partitioned among cell constituents and that coregulation with pigment biosynthesis occurs, no structural evidence for these hypotheses exists. MIB was localized in cells of Oscillatoria limosa (Roth) Agardh at the ultrastructural level using standard gold-labeled antibody techniques. There was no apparent relationship between age of the cells and MIB synthesis; cells that were and were not undergoing active division had similar amounts of MIB label. There was no consistent partitioning of MIB label within cells. However, occasionally, specific label was observed along photosynthetic lamellae, suggesting a potential linkage of MIB synthesis and/or binding to the pigment systems.     

Extent of polyteny in the pericentric heterochromatin of polytene chromosomes of pseudonurse cells of otu (ovarian tumor) mutants of Drosophila melanogaster

In the polytene nuclei of germ-line cells (ovarian pseudonurse cells) of Drosophila melanogaster females mutant for otu ¹¹ (ovarian tumor), the pericentric heterochromatin is much more abundant than in somatic salivary gland cells. This is due to the degree of heterochromatin compaction (and consequently the level of underreplication) being lower in the nurse cells than in the salivary gland cells. The lower level of compaction probably results in a very low degree of position effect gene inactivation in the ovarian nurse cells.     

安徽宿县夹沟寒武-奥陶系界线附近生物群演变及地球化学特征

对宿县夹沟地区跨寒武系与奥陶系的三山子组的碳、氧同位素和微量元素地球化学的研究表明,寒武－奥陶系界线附近有δ＾１３Ｃ和δ＾１８Ｏ的负异常,亲铁元素、亲铜元素的正异常。这些异常与生物群面貌的变化在时间上是同步的。据此认为研究区在寒武纪末可能存在灾变事件。同时,考虑到寒武纪末和奥陶纪初生物群面貌的重大差异,综合国内,外有关研究,认为寒武纪末期可能存在全球性的重大地质事件。     

Reexamination of the immature hominid maxilla from Tangier,Morocco

Reexamination of the immature Upper Pleistocene hominid maxilla from Mugharet el-'Aliya (Tangier), Morocco is undertaken in light of new evidence on the growth and development of Upper Pleistocene hominids. Metric and qualitative comparisons were made with 17 immature Upper Pleistocene maxillae, and with a recent Homo sapiens sapiens sample. No unambiguous criteria for aligning the maxilla with Neandertals were found, although one character, the degree of maxillary flexion on the zygoma, strongly suggests that this child could be a representative of H. s. sapiens. The probable lack of a canine fossa in Mugharet el-'Aliya 1, the primary criterion used previously to align it with Neandertals, cannot be accurately extrapolated to its adult form from this juvenile. The present evidence suggests that it is inappropriate to refer to this fossil as “Neandertal-like” or as a North African “neandertaloid.” Thus, the Tangier maxilla should not be cited as evidence for the presence of Neandertal facial features in North Africa during the Upper Pleistocene. © 1993 Wiley-Liss, Inc.     

Genetic studies of water buffalo blood markers. I. Red cell acid phosphatase,albumin, catalase,red cell α-esterase-3, group-specific component,and protease inhibitor

We have developed the methodologies for typing and family studies to establish the modes of inheritance of water buffalo red cell acid phosphatase (Acp), protease inhibitor (Pi), and group-specific component (Gc) on isoelectric focusing and albumin (Alb), red cell -esterase-3 (Est-3), and catalase (Cat) on polyacrylamide gel electrophoresis. Family studies showed that Pi, Gc, Alb, and Cat are coded by autosomal genes with two codominant alleles, while Est-3 is autosomal with two codominant alleles and a recessive null allele and Acp exhibits three codominant alleles.This project was funded by the Australian Centre for International Agricultural Research through Grant PN 8364 and the Malaysian programme for Intensification of Research in Priority Areas through Grant IRPA 1-07-05-057.     

Partitioning behavior and enrichment of proteins with reversed micellar extraction: I. forward extraction of proteins from aqueous to reversed micellar phase

Protein extractions using aerosol OT (AOT)-isooctane reverse micelle solutions have been studied to explore the potential for separating and enriching proteins with the reversed micellar extraction. The effects of pH, ionic strength, and different cations of chlorides in a bulk aqueous phase and of AOT concentration in an organic phase on the partitioning of lysozyme and myoglobin and the solubilization of water are presented in detail. The extraction of lysozyme was affected by the concentration of potassium or barium but was almost independent of that of sodium or calcium, whose ionic diameter is smaller than that of potassium and barium. For the extraction of myoglobin, however, the effect of barium concentration was not appreciable. Lysozyme could be enriched into the reversed micellar phase up to 30 times the aqueous feed concentration. (c) 1993 John Wiley & Sons, Inc.     

Evolution of insect-plant relationships — a devil''s advocate approach

Most hypotheses concerning the evolution of insect-plant relationships are based on the assumptions that, (1) phytophagous insects reduce plant fitness, and that (2) insect-plant relationships are the result of unconstrained selection. It can be shown, however, that there is little evidence to support these assumptions. As an alternative, it is proposed that the evolution of insect-plant relationships results primarily from autonomous evolutionary events; namely from heritable functional changes within the insects' nervous system that determine plant recognition and ultimately host plant specificity. These changes cannot be evoked by selective ecological agents. They originate from intrinsic changes (mutationssensu lato) within the insect genome. Ecological factors play a secondary role: by either supporting or preventing the establishment of the new genotype with the novel food preference. This paper has been dedicated in warm friendship to Professor Louis M. Schoonhoven, the leading scientist in sensory physiology of phytophagous insects, on the occasion of his 60th birthday.     

An ecosystems approach to base-rich freshwater wetlands,with special reference to fenlands

A survey of base-rich wetlands in The Netherlands is presented. The main area of their occurrence is the low-lying Holocene part of the country, until some thousand years ago a large and coherent wetland landscape: the Holland wetland. The development of various parts of the Holland wetland into marshes, fens and bogs can be understood from hydrological relations in mire basins, as recognized in the distinction of primary, secondary and tertiary mire basin stages. Presently, the remnants of the Holland wetland are separate base-rich wetlands. The succession of their vegetation reflects various abiotic conditions and human influences. Three main developmental periods are distinguished as regards these factors. The first, geological period of mire development is seen as a post-glacial relaxation, with the inertia due to the considerable mass of wetland as a stabilizing factor. Biological “grazing” influences, as an aspect of utilization by humans, converted base-rich wetlands to whole new types in the second, historical period. Presently, mass and harvesting have decreased in importance, and actual successions in terrestrializing turbaries seem to reflect rapidly changing environmental conditions. Human control could well become the most important factor in the future development of wetland nature. The present value of open fen vegetation strongly depends on the continuation of the historical harvesting. The development of wooded fen may help to increase the mass of wetland in the future. Best results in terms of biodiversity are expected when their base state is maintained through water management. The vegetation and hydrology of floating fens in terrestrializing turbaries is treated in some more detail. Various lines and phases in the succession are distinguished. Open fen vegetation at base-rich, yet nutrient-poor sites is very rich in species threatened elsewhere. The fast acidification of certain such fens is attributed to hydrological and management factors. This acidification is illustrated in the profile of a floating raft sample. At the scale of these small fens, the elemental structure comprising base-rich fen, transitional fen and bog vegetation, is not as stable as it was in the large Holland wetland. A critical role seems to be played by the supply of bases with the water influx. The changing base state is supposed to change the nutrient cycling to such an extent that it would be correct to call this trophic excitation of the ecosystem, rather than just eutrophication. Eutrophication indicates a quantitative reaction to an increased nutrient supply, the internal system being unaltered. The drainage of fens, resulting in an increased productivity of the vegetation, provides another example of excitation, to the effect that the functional system is dramatically changed internally.     

Culture of rotifers with reference to some physico-chemical properties of water in nursery pond

Rotifers were cultured with five different organic and inorganic fertilizers in nursery ponds. Of the fertilizers used, mustard oil cake gave significantly (p < 0.01) higher production of rotifers than that of mohua oil cake followed by cow-dung, wheat bran, mixture of NPK and control. The higher production of rotifers was directly related with the higher doses of fertilizers. Among the rotifer species identified, the abundance of Brachionus caudatus and B. forficula were significantly (p < 0.01) higher than others. Available N, available P, exchangeable K and exchangeable Ca and exchangeable Mg were generally higher in ponds where organic fertilizers were used. Proximate composition of rotifers varied depending on the kinds of fertilizers. The multiple correlations of physico-chemical properties were highly significant (p < 0.01) with the growth and production of B. caudatus (R = 0.995), B. forficula (R = 0.932), Trichocerca capucina (R = 0.917), B. patulus (R = 0.901) and B. angularis (R = 0.892) and simply significant (p < 0.05) in the case of Keratella tropica (R = 0.880), Hexarthra intermadia (R = 0.875), B. calyciflorus (R = 0.864) and Filinia spp. (R = 0.856) contributing 91.20%, 86.86%, 84.09%, 81.18%, 79.57%, 77.44%, 76.56%, 74.65% and 73.27% of total effect of water properties on the growth of these species, respectively. The residual effect of nine different physico-chemical properties of water on the production of rotifers was 78.92% which indicates that these properties of water had only 21.08% influence on the production of rotifers.     

Seasonal succession of phytoplankton in a lake of the Paraná river floodplain,Argentina

Phytoplankton biomass, morphological and taxonomic composition, species diversity and productivity were analyzed in a shallow lake of the Middle Paraná River floodplain (El Tigre, 31 ° 41 S and 60° 42 W), between November 1986 and July 1988. Lake inundation (filling and through-flow phases) constituted an intense long-term perturbation in the physical and chemical environment. As the lake filled with river water, K-selected species (netplanktonic filamentous bluegreens, > 37 µm, with low surface area/volume (SA/V) ratios) that had existed prior to filling (late spring 1986) were replaced in summer-fall by r-selected species (nannoplanktonic chlorophytes and cryptophytes, < 37 µm, mainly stout forms with high SA/V ratios). During the through-flow phase, lentic phytoplankton was replaced by lotic flagellate populations due to the direct flushing by river water. During the period of falling water (drainage and isolation phases), nanoplanktonic algae with similar characteristics to those of the filling phase dominated in late winter-spring. Later in the isolation phase, these were succeeded by K-selected species (netplanktonic algae, mainly motile spherical dinoflagellates and filamentous bluegreens with low SA/V ratios). Simultaneously, primary production per unit biomass decreased and total biomass and specific diversity increased. Seasonal changes of phytoplankton in floodplain lakes can be interpreted as the interaction between true successional development (as observed in the drainage and isolation phases) and intermediate disturbance. Using Reynolds' terminology, short-term disturbance (slight inflow of nutrient-rich river water) caused reversion to an earlier stage in the former succession, and long-term disturbance (lake inundation) truncated the successional progression and a new (or shifted) succession was initiated.