Getting closer to a pre-vertebrate genome: the non-LTR retrotransposons of Branchiostoma floridae

Non-LTR retrotransposons are common in vertebrate genomes and although present in invertebrates they appear at a much lower frequency. The cephalochordate amphioxus is the closest living relative to vertebrates and has been considered a good model for comparative analyses of genome expansions during vertebrate evolution. With the aim to assess the involvement of transposable elements in these events, we have analysed the non-LTR retrotransposons of Branchiostoma floridae. In silico searches have allowed to reconstruct non-LTR elements of six different clades (CR1, I, L1, L2, NeSL and RTE) and assess their structural features. According to the estimated copy number of these elements they account for less than 1% of the haploid genome, which reminds of the low abundance also encountered in the urochordate Ciona intestinalis. Amphioxus (B. floridae) and Ciona share a pre-vertebrate-like organization for the non-LTR retrotransposons (<150 copies, < 1% of the genome) versus the complexity associated to higher vertebrates (Homo sapiens >1.3.10(6) copies, > 20% of the genome).     

Lymphoepithelioid cell lymphoma (Lennert's lymphoma). Report of a case with fine needle aspiration cytology

BACKGROUND: Lymphoepithelioid cell lymphoma (LCL) is a rare morphologic variant of peripheral T-cell lymphoma. Although their histopathologic and immunohistochemical findings are well known, the cytopathologic features have not been well documented. This report describes the fine needle aspiration cytology (FNAC) findings of a case of LCL. CASE: A 75-year-old woman presented with cervical, supraclavicular, axillary and mediastinal lymphadenopathy. FNAC of a cervical lymph node was performed. The smears contained a polymorphous infiltrate formed by abundant histiocytes disposed singly or in clusters, small and medium-sized to large atypical lymphoid cells and reactive cells, including eosinophils and plasma cells. Isolated capillary-sized vessels also were observed. Histopathologic and immunohistochemical examination confirmed the diagnosis of Lennert's lymphoma. CONCLUSION: Although histopathologic and immunohistochemical studies were required for a definitive diagnosis, the findings of FNAC in this case appeared distinctive and suggested the possibility of LCL.     

Organelle selection determines agonist-specific Ca2+ signals in pancreatic acinar and beta cells

How different extracellular stimuli can evoke different spatiotemporal Ca2+ signals is uncertain. We have elucidated a novel paradigm whereby different agonists use different Ca2+-storing organelles ("organelle selection") to evoke unique responses. Some agonists select the endoplasmic reticulum (ER), and others select lysosome-related (acidic) organelles, evoking spatial Ca2+ responses that mirror the organellar distribution. In pancreatic acinar cells, acetylcholine and bombesin exclusively select the ER Ca2+ store, whereas cholecystokinin additionally recruits a lysosome-related organelle. Similarly, in a pancreatic beta cell line MIN6, acetylcholine selects only the ER, whereas glucose mobilizes Ca2+ from a lysosome-related organelle. We also show that the key to organelle selection is the agonist-specific coupling messenger(s) such that the ER is selected by recruitment of inositol 1,4,5-trisphosphate (or cADP-ribose), whereas lysosome-related organelles are selected by NAADP.     

Effects of putrescine accumulation in tobacco transgenic plants with different expression levels of oat arginine decarboxylase

Arginine decarboxylase (ADC; EC 4.1.1.19) is a key enzyme in one of the two possible ways to synthesize putrescine (Put) in plants. In previous work ( Masgrau et al. 1997 ), we observed an altered phenotype (growth inhibition, leaf chlorosis and necrosis) in tobacco transgenic plants ( Nicotiana tabacum L. var. Wisconsin-38) containing the oat ADC cDNA under the control of a tetracycline inducible promoter, the severity of which was correlated with Put content. Now we have analysed the T₂ generation of a selected transgenic line (line 52), which in previous generations was characterized by presenting a moderate increase in ADC activity and polyamine levels, but no phenotype alterations. Studying two selected individuals, one with a high expression level of the transgene and the other with a moderate expression level, we demonstrate that only the one with increased polyamine content displays the altered (toxic) phenotype. The possible causes of toxicity have been analysed. The results suggest that either Put or its oxidation products, via diamine oxidase (DAO; EC 1.4.3.6), are the responsible factors for the deleterious effects observed in the transgenic plants.     

Nitrate reductase in cotyledons of cucumber seedlings as affected by nitrate, phytochrome and calcium

Regulation by the active form of phytochrome (P_FR) and the effect of Ca²⁺ was examined with nitrate reductase (NR) in etiolated cucumber ( Cucumis sativus cv. Beilpuig). Nitrate reductase activity (NRA) was studied in excised cotyledons of cucumber seedlings grown in distilled water and in darkness for seven days at 24 ± 0.5°C. All experiments were performed in the dark and a dim green safelight was used during analyses. In etiolated cucumber cotyledons NRA was induced by nitrate and a brief irradiation (15 min) with red light (R) resulted in 62% increase in NRA. This effect was nullified when R was followed immediately by a brief (5 min) far-red light (FR). NRA also showed a semidian (12 h) rhythmicity. Both P_FR, and nitrate effects were age dependent. Calcium seemed to be involved since the phytochrome effect was only observed when calcium was supplied in the external solution. The effect of R on NRA depended on the period of calcium nitrate incubation. An external supply of calcium ionophore mimicked the effect of R and, if supplied to R-irradiated cotyledons, produced a higher NR level than that caused by R alone. This suggested that intracellular free calcium was involved.     

Genetic fine localization of the arrestin (S-antigen) gene 4 cM distal from D2S172

Arrestin is a component of the light transduction cascade that takes place in the outer segment of retinal rods. In situ hybridization and linkage analysis have localized the arrestin gene to a region of 50 cM between CRYG and D2S23/D2S55 on chromosome 2q24–37. We have performed pairwise and multipoint linkage analysis between arrestin and four highly polymorphic markers from this region. The results indicate tight linkage between the gene and the microsatellite D2S172 (Z _max = 9.25 at =0.038). This fine localization of the gene should provide a useful tool for cosegregation analyses involving the arrestin gene.     

Optimizing captive short-beaked echidna (Tachyglossus aculeatus) fecal sample identification and hormonal analysis

The objectives of this study were to develop a fecal marking protocol to distinguish male from female samples during the echidna breeding season and to determine if normalizing fecal progesterone metabolite data for inorganic content improves the detection of biologically relevant changes in metabolite concentrations. Over a period of 6 weeks, four echidnas were provided with green food coloring powder mixed into 20 g of their regular feed with the dose adjusted weekly by 0.05 g. The proportion of organic (feces) versus inorganic matter (sand) in the fecal samples of three echidnas was determined by combustion of organic matter. Hormonal data was then expressed as metabolite concentration per total dry mass (with sand) of extracted sample versus metabolite concentration per total mass of organic material (without sand). The optimal dose of food coloring powder was 0.30 g: this was excreted in the feces of all echidnas within 24 h of consumption with color present for two consecutive days. Correction for inorganic content (sand) did not significantly affect variability of fecal progesterone metabolite levels (mean CV ± SE with sand: 142.3 ± 13.3%; without sand: 127.0 ± 14.4%; W = 6, p = .2500), or the magnitude of change from basal to elevated fecal progesterone metabolite concentrations (mean ± SE with sand: 8.4 ± 1.7; without sand: 6.6 ± 0.5, W = 10, p = .1250). Furthermore, progesterone metabolite concentrations before and after correction for sand contamination correlated strongly (r = .92, p = < .001). These methods will facilitate future reproductive endocrinology studies of echidna and other myrmecophagous species.     

A note on 'plotless' methods for estimating bacterial cell densities

R oser , D., N edwell , D.B. & G ordon , A. 1984. A note on "plotless" methods for estimating bacterial cell densities. Journal of Applied Bacteriology 56 , 343–347.
'Plotless' techniques for determining population densities have been developed for, and applied to, higher plant populations. They can often be carried out more rapidly than techniques involving total counts of individuals in plots, or quadrants, but such plotless techniques have not been generally applied to the estimation of densities of bacterial cells. Direct microscopical counting of cell numbers in a field of view, an example of a plot-related method, has been traditionally used for micro-bial cell counts. In this study 'plot' and 'plotless' methods on a variety of bacterial samples are compared. Estimates of bacterial cell density were obtained by measuring the distance of cells from a fixed point in a field of view. The values, which were more rapidly obtained, were directly correlated with total cell counts. Although there was some apparent deviation from a perfect 1:1 relationship with total counts, as indicated by a correlation coefficient less than 1.0, there were no significant differences between the replicated counts of bacteria on samples of tissue from the surface of Hypholoma basidiocarps ( P < 0.05). This indicated that the methods of enumeration were comparable. The distance-related estimates could readily be obtained from fields of view with cell densities varying over several orders of magnitude. It was more rapidly applied, particularly at high density, and the method was applicable not only to random cell distributions but also to the non-random distributions encountered when microbial cells aggregated into micro-colonies. The method appears to be particularly well-suited for automated, digitized, direct counting procedures, as well as to estimating bacterial numbers on membrane filters and natural substrates.     

Adoptive immunotherapy of leukemia in the rat, without graft-VS-host complications.

PVG rats bearing a transplantable T cell leukemia were treated with large inocula of lymphoid cells from AUG rats sensitized either against the leukemia or against PVG lymphocytes. AUG and PVG bear identical Ag-B antigens but differ at minor loci, including the Pta loci, which code for differentiation antigens expressed only on peripheral T lymphocytes. Treatment with AUG cells immune to either the PVG leukemia or normal PVG cells resulted in prolonged survival of leukemic rats, a profound but ephemeral leukopenia and prolonged disappearance of leukemic cells from lymphoid tissue. All treated animals, however, eventually died with large, discrete deposits of leukemic cells in both hard and soft tissues. Despite the deliberate mismatching of host and donor cells for minor transplanation antigens, no evidence of GVH symptoms was observed in treated rats. This was interpreted as a result of directing the adoptive immune response to antigens of restricted distribution, i.e., on leukocytes and not on somatic cells.