Anaerobic Naphthalene Degradation by Microbial Pure Cultures under Nitrate-Reducing Conditions

Pure bacterial cultures were isolated from a highly enriched denitrifying consortium previously shown to anaerobically biodegrade naphthalene. The isolates were screened for the ability to grow anaerobically in liquid culture with naphthalene as the sole source of carbon and energy in the presence of nitrate. Three naphthalene-degrading pure cultures were obtained, designated NAP-3-1, NAP-3-2, and NAP-4. Isolate NAP-3-1 tested positive for denitrification using a standard denitrification assay. Neither isolate NAP-3-2 nor isolate NAP-4 produced gas in the assay, but both consumed nitrate and NAP-4 produced significant amounts of nitrite. Isolates NAP-4 and NAP-3-1 transformed 70 to 90% of added naphthalene, and the transformation was nitrate dependent. No significant removal of naphthalene occurred under nitrate-limited conditions or in cell-free controls. Both cultures exhibited partial mineralization of naphthalene, representing 7 to 20% of the initial added ¹⁴C-labeled naphthalene. After 57 days of incubation, the largest fraction of the radiolabel in both cultures was recovered in the cell mass (30 to 50%), with minor amounts recovered as unknown soluble metabolites. Nitrate consumption, along with the results from the ¹⁴C radiolabel study, are consistent with the oxidation of naphthalene coupled to denitrification for NAP-3-1 and nitrate reduction to nitrite for NAP-4. Phylogenetic analyses based on 16S ribosomal DNA sequences of NAP-3-1 showed that it was closely related to Pseudomonas stutzeri and that NAP-4 was closely related to Vibrio pelagius. This is the first report we know of that demonstrates nitrate-dependent anaerobic degradation and mineralization of naphthalene by pure cultures.     

The insect cellular immune response

The innate immune system of insects is divided into humoral defenses that include the production of soluble effector molecules and cellular defenses like phagocytosis and encapsulation that are mediated by hemocytes. This review summarizes current understand- ing of the cellular immune response. Insects produce several terminally differentiated types of hemocytes that are distinguished by morphology, molecular and antigenic markers, and function. The differentiated hemocytes that circulate in larval or nymphal stage insects arise from two sources： progenitor cells produced during embryogenesis and mesodermally derived hematopoietic organs. Regulation of hematopoiesis and hemocyte differentiation also involves several different signaling pathways. Phagocytosis and encapsulation require that hemocytes first recognize a given target as foreign followed by activation of downstream signaling and effector responses. A number of humoral and cellular receptors have been identified that recognize different microbes and multicellular parasites. In turn, activation of these receptors stimulates a number of signaling pathways that regulate different hemocyte functions. Recent studies also identify hemocytes as important sources Of a number of humoral effector molecules required for killing different foreign invaders.     

Permafrost Distribution Drives Soil Organic Matter Stability in a Subarctic Palsa Peatland

Palsa peatlands, permafrost-affected peatlands characteristic of the outer margin of the discontinuous permafrost zone, form unique ecosystems in northern-boreal and arctic regions, but are now degrading throughout their distributional range due to climate warming. Permafrost thaw and the degradation of palsa mounds are likely to affect the biogeochemical stability of soil organic matter (that is, SOM resistance to microbial decomposition), which may change the net C source/sink character of palsa peatland ecosystems. In this study, we have assessed both biological and chemical proxies for SOM stability, and we have investigated SOM bulk chemistry with mid-infrared spectroscopy, in surface peat of three distinct peatland features in a palsa peatland in northern Norway. Our results show that the stability of SOM in surface peat as determined by both biological and chemical proxies is consistently higher in the permafrost-associated palsa mounds than in the surrounding internal lawns and bog hummocks. Our results also suggest that differences in SOM bulk chemistry is a main factor explaining the present SOM stability in surface peat of palsa peatlands, with selective preservation of recalcitrant and highly oxidized SOM components in the active layer of palsa mounds during intense aerobic decomposition over time, whereas SOM in the wetter areas of the peatland remains stabilized mainly by anaerobic conditions. The continued degradation of palsa mounds and the expansion of wetter peat areas are likely to modify the bulk SOM chemistry of palsa peatlands, but the effect on the future net C source/sink character of palsa peatlands will largely depend on moisture conditions and oxygen availability in peat.     

Identification to the species level of <Emphasis Type="Italic">Lactobacillus</Emphasis> isolated in probiotic prospecting studies of human,animal or food origin by 16S-23S rRNA restriction profiling

Background  

The accurate identification of Lactobacillus and other co-isolated bacteria during microbial ecological studies of ecosystems such as the human or animal intestinal tracts and food products is a hard task by phenotypic methods requiring additional tests such as protein and/or lipids profiling.     

Type-C RNA Virus Gene Expression in Human Tissue

Partially purified fractions of human tissues have been analyzed by competition radioimmunoassay for the presence of two of the principle structural components of type-C RNA viruses, the major core protein (p27 to p30) and the major envelope glycopeptides (gp69/71). Screening of tissues was carried out by use of a heterologous assay system of (125)I-labeled Rauscher murine virus p30 antigen and anti-RD 114 virus serum which was found to detect a class of interspecies determinants common to murine, feline, and primate viruses. A competitor with the same apparent affinity for antibody binding as that of purified viral core proteins was found in relatively high concentration in tissues from patients with systemic lupus erythematosus, in some neoplastic tissues, and also in normal human tissues. This competitor from a lupus spleen chromatographed on phosphocellulose and showed size fractionation during gel filtration similar to known p27 to p30 viral proteins. An immunologically reactive protein was also demonstrated by immunodiffusion and by immunoprecipitation of (125)I-labeled human protein with anti-RD 114 p28 serum. Analysis of these human competitor proteins with homologous assay systems of viral core proteins and corresponding antisera showed that all, including the normal tissue extracts, appear similar to core proteins of known viruses, especially the RD 114 and woolly monkey species. A hypothesis suggested by these data is that many, if not all, humans harbor at least part of the genome of one or more type-C viruses, the properties of which are similar to those of viruses from other mammalian species, particularly primates.     

Susceptibility of spotted wolffish Anarhichas minor to experimental infection with nodavirus and infectious pancreatic necrosis virus

The spotted wolffish Anarhichas minor is a promising new species for cold-water aquaculture. The broad host-range of piscine nodavirus (NV) and infectious pancreatic necrosis virus (IPNV) makes them potentially pathogenic to new fish species in aquaculture. IPNV and NV strains highly pathogenic in farmed Atlantic salmon Salmo salar and halibut Hippoglossus hippoglassus, respectively, in Norway were used for the challenge of spotted wolffish. In general, water-borne infection with IPNV and NV resulted in significant mortality among juveniles <1 g. Cumulative mortality after bath-challenge and cohabitation was 60 to 75% in the smallest juveniles (0.3 g). Intramuscular and intraperitoneal injection of NV was 100% lethal to wolffish of 10 g, and the groups at 12 degrees C died before those at 7 degrees C. No cohabitants of this size died, but NV was still detectable in these individuals after 10 wk. A persistent IPNV infection with low mortality developed in bath-challenged juveniles of 0.7 g, in which IPNV was still detectable 4 mo later. This study comprises a demonstration of experimental viral infections in cultured spotted wolffish, although to date no natural outbreaks of viral diseases have been reported in this species.