Geothermal bryophyte habitats in the South Sandwich Islands,maritime Antarctic

Question: How does geothermal activity influence terrestrial plant colonization, species composition and community development in the Antarctic? Location: South Sandwich Islands, maritime Antarctic. Methods: Bryophytes were documented during a biological survey of the archipelago in January and February 1997. Particular attention was given to sites under current or recent influence of geothermal activity. Temperature profiles obtained across defined areas of activity on several islands were linked with the presence of specific bryophytes. Results: Greatest bryophyte richness was associated with geothermally influenced ground. Of 35 moss and nine liverwort species recorded, only four mosses were never associated with heated ground, while eight of the liverworts and 50% of the mosses were found only on actively or recently heated ground. Some species occur in unheated sites elsewhere in the maritime Antarctic, but were absent from such habitats on the South Sandwich Islands. Several species occurred in distinct zones around fumaroles. Maximum temperatures recorded within the upper 0.5 cm of the vegetation surface were 40 ‐ 47 °C, with only Campylopus introflexus tolerating such temperatures. Maximum temperatures 2.5 or 5 cm below the vegetation surface of this moss reached 75 °C. Other bryophytes regularly present in zoned vegetation included the mosses Dicranella hookeri, Sanionia georgico‐uncinata, Pohlia nutans and Notoligotrichum trichodon, and the liverworts Cryptochila grandiflora and Marchantia berteroana. Surface temperatures of 25 ‐ 35 °C and subsurface temperatures of 50 ‐ 60 °C were recorded in these species. Conclusions: These exceptional plant communities illustrate the transport of viable propagules into the Antarctic. Individually ephemeral in nature, the longer term existence of geothermal habitats on islands along the Scotia Arc may have provided refugia during periods of glacial expansion, facilitating subsequent recolonization of Antarctic terrestrial habitats.     

The Effect of a Spinal Cord Hemisection on Changes in Nitric Oxide Synthase Pools in the Site of Injury and in Regions Located Far Away from the Injured Site

1. The present study was designed to examine the nitric oxide synthase activities (constitutive and inducible) in the site of injury in response to Th10-Th11 spinal cord hemisection and, to determine whether unilateral disconnection of the spinal cord influences the NOS pools on the contra- and ipsilateral sides in segments located far away from the epicentre of injury.2. A radioassay detection was used to determine Ca²⁺-dependent and inducible nitric oxide synthase activities. Somal, axonal and neuropil neuronal nitric oxide synthase was assessed by immunocytochemical study. A quantitative assessment of neuronal nitric oxide synthase immunoreactivity was made by an image analyser. The level of neuronal nitric oxide synthase protein was measured by the Western blot analysis.3. Our data show the increase of inducible nitric oxide synthase activity and a decrease of Ca²⁺-dependent nitric oxide synthase activity in the injured site analysed 1 and 7 days after surgery. In segments remote from the epicentre of injury the inducible nitric oxide synthase activity was increased at both time points. Ca²⁺-dependent nitric oxide synthase activity had decreased in L5-S1 segments in a group of animals surviving for 7 days. A hemisection performed at thoracic level did not cause significant difference in the nitric oxide synthase activities and in the level of neuronal nitric oxide synthase protein between the contra- and ipsilateral sides in C6-Th1 and L5-S1 segments taken as a whole. Significant differences were observed, but only when the spinal cord was analysed segment by segment, and/or was divided into dorsal and ventral parts. The cell counts in the cervicothoracic (C7-Th1) and lumbosacral (L5-S1) enlargements revealed changes in neuronal nitric oxide synthase immunoreactivity on the ipsilateral side of the injury. The densitometric area measurements confirmed the reduction of somal, neuropil and axonal neuronal nitric oxide synthase immunoreactive staining in the ventral part of rostrally oriented segments.4. Our findings provide evidence that the changes in nitric oxide synthase pools are limited not only to impact zone, but spread outside the original lesion. The regional distribution of nitric oxide synthase activity and neuronal nitric oxide synthase immunoreactivity, measured segment by segment shows that nitric oxide may play a significant role in the stepping cycle in the quadrupeds.     

A simple, rapid and effective method for total RNA extraction from Lentinula edodes

A rapid, inexpensive and reliable method for total RNA extraction from fruiting bodies of Lentinula edodes containing large quantities of polysaccharides and secondary metabolites is described. An initial extraction step using saturated NaCl solution facilitates the separation of nucleic acids from contaminants and, after further extraction with organic solvents and precipitation with 2-propanol, total RNA of high purity and suitable for applications such as cDNA synthesis, RT-PCR and Northern blot hybridization was obtained. The procedure may also have wider applicability for total RNA extraction from the tissues of other mushrooms.     

Analysis by enzyme-linked immunosorbent assay and immunoblot of the antibody responses of patients infected with Mycobacterium marinum

The serum antibody responses of a total of 14 patients with active or recently cured Mycobacterium marinum infections were analysed via a combination of enzyme-linked immunosorbent assay (ELISA) and the immunodevelopment of Western blots of M. marinum antigen. Normal human sera and sera from patients with active pulmonary tuberculosis were also analysed as controls. The detectable IgG response of M. marinum patients, as demonstrated by ELISA, was highly variable and did not differ significantly from normal controls. IgA and IgM levels were generally low in the M. marinum patients and were not significantly different from normal controls. Immunodevelopment of Western blots of M. marinum antigen with the sera of patients with M. marinum infections revealed that a number of antigens were recognised. Of particular note was an 18-kDa species that was recognised by 11 out of 14 patients (and by none of the normal controls). The 18-kDa antigen may be a useful serodiagnostic marker in the identification of M. marinum infections.     

博莱霉素同系物对癌基因表达的影响

应用快速酶联免疫法（ELISA）及Northern印迹杂交法研究了博莱霉素（BLM）同系物诱导癌基因表达的作用．通过检测P21和c－myc蛋白表达的改变和药物在RNA的转录水平上对癌基因表达的影响,证明BLM能够抑制c－myc基因的表达．这种抑制作用不仅发生在蛋白质的翻译水平,而且可能发生在RNA的转录水平上．BLMA6及A2对Ras基因亦有极显著的抑制,提示其亦为以p21蛋白为靶点的抗癌抗生素．A6、A2与A5之间的区别提示在同系物之间可能存在不同的抗癌机理     

Disruptive effects of prefeeding and haloperidol administration on multiple measures of food-maintained behavior in rats

Four rats responded under a choice reaction-time procedure. At the beginning of each trial, the rats were required to hold down a center lever for a variable duration, release it following a high- or low-pitched tone, and press either a left or right lever, conditionally on the tone. Correct choices were reinforced with a probability of .95 or .05 under blinking or static houselights, respectively. After performance stabilized, disruptive effects of free access to food pellets prior to sessions (prefeeding) and intraperitoneal injection of haloperidol were examined on multiple behavioral measures (i.e., the number of trials completed, percent of correct responses, and reaction time). Resistance to prefeeding depended on the probability of food delivery for the number of trials completed and reaction time. Resistance to haloperidol, on the other hand, was not systematically affected by the probability of food delivery for all dependent measures.     

alpha B-crystallin is a cytoplasmic interaction partner of the kidney-specific cadherin-16

The Ca^2 +-dependent membrane-spanning classical cadherins bind directly to cytosolic catenins. This cadherin-catenin interaction is known to be critical for the fundamental role of cadherins in cell-cell adhesion. The small subfamily of the 7D-cadherins, however, cannot interact with catenins due to their highly truncated cytoplasmic tail. Thus far, no cytoplasmic interaction partner for the 7D-cadherins has been described. With the use of the cytoplasmic domain of the Ksp (kidney-specific)-cadherin, which belongs to the family of 7D-cadherins, as bait in affinity chromatography with human kidney lysates, the small heat-shock protein αB-crystallin was identified by matrix-assisted laser desorption/ionization-time-of-flight analysis as a cytosolic binding partner of Ksp-cadherin. This interaction was verified by co-immunoprecipitation analysis. With the use of overlapping peptides representing the entire αB-crystallin molecule, the N-terminal part of αB-crystallin, which does not possess chaperone activity, was identified as responsible for the binding to Ksp-cadherin. This interaction was found to be specific since only the cytoplasmic domain of Ksp-cadherin, but not LI (liver-intestine)-cadherin (another member of the 7D-cadherin family), interacted with αB-crystallin. In the human kidney, both αB-crystallin and Ksp-cadherin co-localize to cells of the collecting duct. They also co-localize with the actin cytoskeleton and co-precipitate with the latter. These findings suggest that the interaction of Ksp-cadherin with αB-crystallin is important for the connection of Ksp-cadherin to the cytoskeleton and thus for maintaining tissue integrity in the kidney.