Paleoecology and dynamics of forest ecosystems in Central Evenkia during the past 2400 years

New data on the composition of surface assemblages of plant macroremains from soil and swamp samples have been obtained in the study of geomorphologically different localities in the middle reaches of the Nizhnyaya Tunguska River. The results of paleocarpological analysis of forest soil sections supported by relevant palynological and geochronological data are presented. Natural changes of the forest cover over the past 2400 years and quantitative characteristics of the paleoclimate during each stage are described.Translated from Ekologiya, No. 1, 2005, pp. 3–10.Original Russian Text Copyright © 2005 by Koshkarova, Koshkarov.     

Fetal phenotype of Prader–Willi syndrome due to maternal disomy for chromosome 15

Prader–Willi syndrome (PWS) results from either paternal deletion of 15q11–q13, or maternal uniparental disomy (UPD) of chromosome 15 or imprinting center mutation. Prenatal diagnosis of PWS is currently indicated for chromosomal parental translocation involving chromosome 15 and for decreased fetal movements during the third trimester of gestation. Here we present the prenatal diagnosis of PWS during the first trimester of gestation and autopsy findings. Chorionic villus sampling (CVS) was performed for advanced maternal age at 13 weeks' gestation. CVS showed mosaicism including cells with a normal karyotype and cells with trisomy 15. Amniocentesis showed cells with a normal karyotype. Molecular analysis demonstrated that the fetus had a typical PWS abnormal methylation profile and maternal disomy for chromosome 15. Fetal ultrasound examination showed slightly enlarged lateral ventricles and hypoplasic male external genitalia without intra-uterine growth retardation. The autopsy showed a eutrophic male fetus with facial dysmorphy, hypoplasic genitalia, abnormal position of both feet and posterior hypoplasia of the corpus callosum. This report points out that in a karyotypically normal fetus with ambiguous male external genitalia and cerebral anomalies, extensive cytogenetic and molecular biology studies are strongly recommended because of risk of PWS. Copyright © 2003 John Wiley & Sons, Ltd.     

A study of the growth and decay of cigarette smoke NOx in ambient air under controlled conditions

The amount of NO₂ and NO produced by the machine smoking of cigarettes was determined for 15 commercial Canadian brands. Average yield of NO was 1.44 μmoles or about 13% of the average reported for American cigarettes. Levels of NO₂ were less than 12% of NO and were probably due to the oxidation of NO. In order to assess the contribution of tobacco smoke to levels of NO in ambient air, 5 brands of cigarettes were smoked in 27 cubic meter controlled environment room. Ventilation conditions were either 2.5 or 5.0 air changes per hour (ACH) and each experiment was replicated 3 times for a total of 30 experiments. Ventilation rates of 0.3 and 1.5 ACH were also selected in a second series of experiments in which only one brand of cigarette was smoked. Least squares estimates for the effective ventilation rates were obtained in the usual manner after linearizing the decay portion of the NO time curve. In each of the experiments, the regression explained at least 95% of the variation in the levels of NO with time. Loss of NO due to factors other than ventilation appeared to be constant within experimental error and averaged 2.22 ACH. Equilibrium values for NO were grossly underestimated when results from currently accepted proecedures for smoke analysis were used in modeling the growth and decay of NO. Goodness-of-fit was improved when equilibrium values were estimated based on observed levels in ambient air. This approach may be more suitable for evaluating the potential contribution of cigarette smoke to levels of indoor air pollutants.     

Risky health and safety habits related to perceived value of the future

Risk homeostasis theory postulates that people accept a specific level (target level) of risk in a given activity in return for benefits accruing from that activity. It follows that, if people expect a great deal from the future, the less likely they are to jeopardise it by taking risks in respect of their health and safety. One effective method for reducing target level of risk are incentives, and the available literature contains ample evidence of the effectiveness of incentives programmes in accident prevention. As incentives essentially imply an enhanced quality of life in the future, the question arises as to how expectations of the future may be related to health and safety habits. In order to explore the relationship between perceived value of the future and health and safety habits, an analysis of the psychological literature on individual differences in future time orientation/perspective is presented. Four factors are identified: (1) clear ideation of the future, (2) active planning for the future, (3) time pressure, and (4) optimistic expectations about events outside one's own control. It is hypothesised that factors (1) and (2) are associated with positive health and safety habits, while factors (3) and (4) may characterise individuals with relatively high target levels of physical risk. Research questions and procedures for the study of these relationships are discussed.     

Loss of genetic diversity in Harpacticoida near offshore platforms

Offshore oil and gas production platforms can be a source of chronic stress that could lead to sublethal impacts on resident benthic organisms. In June 1993 and January 1994, genetic diversity of Harpacticoida (Copepoda) living proximal to operating, offshore platforms in the Gulf of Mexico was estimated to test if platforms are associated with strong selective pressures. Because harpacticoids have short generation times and direct benthic development, they are suitable organisms for examining population responses. Genetic diversity was estimated by comparing restriction fragment length polymorphisms generated from mitochondrial DNA amplified by the polymerase chain reaction on individuals of five species (Cletodes sp., Enhydrosoma pericoense, Normanella sp., Robertsonia sp., and Tachidiella sp.). Populations living at Near regions (stations<50 m from a platform) had significantly less haplotype diversity than populations of the same species living at Far regions (stations>3 km from a platform). The levels of haplotype diversity exhibited by the Far populations were similar at three different platforms located hundreds of kilometers apart. The differences in haplotype diversity between Near and Far regions were the result of a higher proportion of dominant haplotypes, and a loss of less common haplotypes. Haplotypic diversity was inversely correlated with a multivariate measurement of levels of sediment contaminants. The pattern of haplotype diversity on the Gulf of Mexico continental shelf seems to consist of a uniform level of haplotype diversity, punctuated by islands of lower diversity around oil and gas platforms. The selective pressures that lead to a loss of genetic diversity may be the result of contaminants, other differences in the physico-chemical environment, or disturbance in general.     

Planktonic bioluminescence in the pack ice and the marginal ice zone of the Beaufort Sea

An icebreaker cruise into the Beaufort Sea in the fall of 1986 provided a unique opportunity for studying planktonic bioluminescence in ice fields and in the marginal ice zone. Bathyphotometer casts (bioluminescence intensity, seawater temperature, beam attenuation coefficient, and salinity) and biological collections were made to a depth of 100 m. A light budget, which describes the planktonic species responsible for the measured bioluminescence, and a dinoflagellate species budget were constructed from the mean light output from luminescent plankton and plankton counts. The vertical distribution of bioluminescence among the ice stations was similar. The maximum intensities were 2 to 8×10⁶ photons s^-1 cm^-3 in the upper 50 m of the sea-ice interface. The marginal ice zone station (MIZ) exhibited a maximum intensity of 2 to 3×10⁸ photons s^-1 cm^-3 between 5 and 30 m depth. At Ice Station 2, Metridia longa and their nauplii contributed approximately 80% of stimulable bioluminescence in the upper 10 m but, overall, Protoperidinium spp. dinoflagellates contributed most of the light to a depth of 100 m. In the MIZ, Protoperidinium spp. dinoflagellates contributed 90% of the light within the upper 10 m, decreasing to 43% of the contributed light at a depth of 40 m. Below 40 m, dinoflagellate bioluminescence decreased to a few percent of the total to a depth of 90 m. Metridia spp. copepods contributed more than 50% of the light at depths from 40 to 90 m. Ostracods, larvaceans, and euphausiid furcilia contributed <1% of all bioluminescence at all depths sampled. Correlation analyses between measured bioluminescence (photons s^-1 cm^-3), the number of bioluminescent dinoflagellates and the light budget for the MIZ indicated highly significant associations: r=0.919, p=0.001, and r=0.912, p<0.001, respectively (Student's two-tailed t-tests). Bioluminescence was negatively correlated with seawater salinity at all stations (p=0.001). Maximum bioluminescence was measured in the less saline surface waters at all stations.     

Bacterivory: a novel dual role for thraustochytrids in the sea

Two thraustochytrids, Thraustochytrium striatum Schneider and Schizochytrium mangrovei Raghukumar, isolated in 1989 in axenic cultures using pine pollen in seawater from mangroves in Goa, India, were observed in continuous-flow chambers. When grown in the presence of bacteria, both species produced amoebae, which moved using pseudopodia and phagocytosed bacterial cells. Several amoebae were produced in sporangia, or isolated vegetative cells transformed directly into amoebae. These findings were confirmed with several single-cell isolations of the protists. The demonstration of phagotrophic amoebae in these organisms suggests a dual role for thraustochytrids in nature, namely a fungus-like breakdown of complex organic molecules as well as bacterivory. This phenomenon also places the thraustochytrics in a unique relationship with many other protistan groups.     

Laboratory observations on spawning,fecundity and early development of a mesopelagic ostracod,Conchoecia pseudodiscophora,from the Japan Sea

The fate of the polycyclic aromatic hydrocarbon [³H]benzo[a]pyrene (BaP) was examined in two species of scleractinian corals, Favia fragum (Esper) and Montastrea annularis (Ellis and Solander), which were collected in the patch reefs surrounding Alina's Reef (25°23.25N; 80°09.8W) in Biscayne National Park, Florida, USA, in July, 1990. Corals were exposed to initial concentrations of 5 g/l in a simple static system for 25 h. BaP uptake was estimated from the disappearance of BaP from the water. Uptake rates were 6.5±0.7 and 10.8±0.2 g BaP cm^-2h^-1 for F. fragum and M. annularis, respectively, at initial BaP concentrations and were directly proportional to the concentration of BaP in the water. The separation of zooxanthellae from coral tissue revealed that zooxanthellae can accumulate up to 53 and 64% of the total BaP-derived radioactivity present in F. fragum and M. annularis, respectively. Both corals metabolized BaP slowly, as most of the accumulated radioactivity was present as the unmetabolized chemical. However, aqueous and organic-soluble metabolites were found in both the animal and zooxanthellae fractions. Analysis by high-performance liquid chromatography (HPLC) revealed that both species of corals metabolized BaP to various tetrols, triols, dihydrodiols, quinones and phenols, although the pattern of metabolites differed between species. Zooxanthellae contained some of the same Phase I metabolites found in the animal tissue; however, tetrols and triols were absent in extracts from the zooxanthellae. The elimination of BAP from corals was also slow; approximately 38 and 65% of the accumulated radioactivity was still present in F. fragum and M. annularis, respectively, 144 h following the transfer of exposed corals to an uncontaminated flow-through seawater system.