Root trenching: a useful tool to estimate autotrophic soil respiration? A case study in an Austrian mountain forest

We conducted a trenching experiment in a mountain forest in order to assess the contribution of the autotrophic respiration to total soil respiration and evaluate trenching as a technique to achieve it. We hypothesised that the trenching experiment would alter both microbial biomass and microbial community structure and that fine roots (less than 2 mm diameter) would be decomposed within one growing season. Soil CO₂ efflux was measured roughly biweekly over two growing seasons. Root presence and morphology parameters, as well as the soil microbial community were measured prior to trenching, 5 and 15 months after trenching. The trenched plots emitted about 20 and 30% less CO₂ than the control plots in the first and second growing season, respectively. Roots died in trenched plots, but root decay was slow. After 5 and 15 months, fine root biomass was decreased by 9% (not statistically different) and 30%, (statistically different) respectively. When we corrected for the additional trenched-plot CO₂ efflux due to fine root decomposition, the autotrophic soil respiration rose to ~26% of the total soil respiration for the first growing season, and to ~44% for the second growing season. Soil microbial biomass and community structure was not altered by the end of the second growing season. We conclude that trenching can give accurate estimates of the autotrophic and heterotrophic components of soil respiration, if methodological side effects are accounted for, only.     

干旱胁迫对苗木蒸腾耗水日变化的影响

采用BP340 0精密电子天平 ,于 2 0 0 2年夏季研究了在不同水分胁迫条件下 ,4种北方主要造林树种苗木的日蒸腾耗水速率及实际耗水量变化规律 .结果表明 ,在正常水分条件下 ,各苗木的日最大耗水速率出现在 10 :0 0— 14 :0 0之间 ,阔叶树种的蒸腾耗水速率远远大于针叶树种 ,是针叶树种的 5～ 7倍 ,苗木的耗水速率排序为 :黄栌 >火炬树 >侧柏 >油松 ;1年生的黄栌和火炬树与 5年生侧柏的日耗水量相差不大 ,是油松的 1倍 .当苗木受到干旱胁迫后 ,苗木的日最大耗水速率会提前 ,蒸腾速率迅速下降 ,但下降幅度不同 ,耗水速率排序为 :火炬树 >黄栌 >油松 >侧柏 .在中等干旱胁迫下 ,油松、火炬树、侧柏、黄栌的日平均耗水速率分别下降了 5 4 0 %、6 8 6 %、87 2 %和 90 2 % ;侧柏和黄栌之间 ,油松和火炬树之间的日耗水量基本相同 ,但侧柏和黄栌只有油松和火炬树的一半 ;干旱胁迫继续加重后 ,油松、火炬树、侧柏、黄栌的日平均耗水速率只有水分正常条件下的 15 7%、12 1%、4 3%和 9 2 % ,日耗水总量下降到 5 %～10 % ,4个树种间相差不大 .     

Primary meningeal T-cell lymphoma in a harbor seal (Phoca vitulina).

A 15-year-old female harbor seal (Phoca vitulina) was referred to the Nantes Veterinary School, Nantes, France, with a clinical history of anorexia, seizures, and left hemiplegia. Cerebrospinal fluid analysis revealed large numbers of neoplastic lymphoid cells. After injection of a contrast agent into the cerebrospinal space, radiographs demonstrated an asymmetry of the right lateral ventricle. Necropsy examination revealed a marked edema of the right frontal lobe, extending to the basal nuclei and thalamus in the brain. Histological examination of the brain revealed leptomeningeal lymphoma. Immunohistochemical labeling demonstrated that the neoplasm was of T-cell origin. No significant macroscopic or microscopic lesions were observed in the other organs examined, including lymphoid organs. This is the first report of primary leptomeningeal lymphoma in a harbor seal.     

Two new genera and two new species of proteocephalidean tapeworms (Eucestoda) from reptiles and amphibians in Australia

The examination of the type series of Ophiotaenia Gallardi (Johnston, 1911) (syn. Proteocephalus gallardi Johnston, 1911) revealed that it is a mixture of two species of different genera. Lectotype of Ophiotaenia gallardi is designated and the species is redescribed on the basis of it, conspecific paralectotypes and additional materials. The remaining part of the type series belongs to Vandiermenia gen. n. (Acanthotaeniinae), with V Beveridgei sp. n. as the type- and only species. The new genus differs from all other acanthotaeniine genera, i.e. Rostellotaenia Freze, 1963, Acanthotaenia von Linstow, 1903 and Kapsulotaenia Freze, 1963, by the presence of cortical uterine stem and paramuscular vitelline follicles, particular structure of the internal longitudinal musculature (absent laterally and more developed than in the three above-mentioned genera) and testes limited in two fields separated medially. Type series of Ophiotaenia mjobergi (Nybelin, 1917) (syn. Crepidobothrium mjobergi Nybelin, 1917), O. amphiboluri (Nybelin, 1917) (syn. Crepidobothrium amphiboluri Nybelin, 1917), O. striata (Johnston, 1914) (syn. Acanthotaenia striata Johnston, 1914) and O. longmani Johnston, 1916 are revised and compared with Ophiotaenia gallardi. Australotaenia hylae (Johnston, 1912) comb. n. is proposed for Ophiotaenia hylae Johnston, 1912. Australotaenia gen. n. differs from the remaining genera of the subfamily Acanthotaeniinae by (1) the Type 2 of the formation of the uterus (sensu de Chambrier et al. 2004) (all the other acanthotaeniines have the Type 1 of uterine development), (2) the cortical position of the uterine stem (all the other genera have medullary uterine stem) and (3) the morphology of the internal longitudinal musculature, which is composed of few well-developed bundles of fibres (in contrast to the other genera). The new genus also differs from ?by eggs not in clusters, the presence of two testicular fields (versus one in Vandiermenia) and the structure of the longitudinal internal musculature with only 8-10 bundles (versus formed by numerous bundles and with the presence of secondary muscles in Vandiermenia). Ophiotaenia sp. sensu de Chambrier (2004), a parasite of Litoria moorei, is described as Australotaenia grobeli sp. n., which can be distinguished from Australotaenia hylae by the smaller number of testes (46-76 versus 74-106), greater cirrus-sac length/width of proglottis ratio (27-33% versus 17-19%) and the smaller ovary width/proglottis width ratio (55-63% versus 68-71%).     

ermB-mediated erythromycin resistance in Streptococcus uberis from bovine mastitis

The ermB gene was identified in 111 erythromycin resistant isolates of Streptococcus uberis from cases of bovine mastitis associated either with a constitutive (47/111) or an inducible (64/111) phenotype, as well as a phenotypic resistance to all macrolides tested. Resistance to lincosamides was identified in 14 other isolates of S. uberis from bovine mastitis cases and was mainly mediated by the linB gene; resistance conferred by a combination of two genes (linB–lnuD, ermB–linB) was also detected.     

Strong differentiation within Diplocarpon rosae strains based on microsatellite markers and greenhouse-based inoculation protocol on Rosa

The haploid ascomycete Diplocarpon rosae is the causal agent of black spot disease on roses, a widespread and devastating disease in the outdoor landscape. In this study, we established a Eurasian collection of 77 monoconidial strains of D. rosae: 50 strains collected on cultivated roses in Europe and Asia, and 27 strains on wild roses in Kazakhstan. To provide tools to describe its biology and to study its genetic diversity, we sequenced two strains of D. rosae using Illumina paired-end technology. The genome sizes of these two strains were estimated at 31.1 and 35.2 Mb, which are two times smaller than the genome size of the unique strain previously published. A BUSCO analysis confirmed a genome duplication of the strain previously sequenced and partial gene duplication of strains analysed in this study. Using the two genome sequences, 27 polymorphic microsatellite markers were identified. Polymorphism analysis of the 77 strains revealed a strong genetic differentiation between strains from cultivated and wild roses, and a lower diversity within the fungal population from cultivated roses compared to the population from wild roses. Pathogenicity of 10 strains was evaluated on 9 rose cultivars inoculated in the greenhouse. Disease scoring allowed the classification of strains into three groups and the characterization of resistance of rose cultivars. Good correlation observed between resistance scoring in greenhouse conditions and in the field indicates that pathogenicity assays in controlled conditions could be very useful in the near future to rapidly characterize the resistance of new rose varieties to black spot disease.     

Expression of adiponectin and its receptors (AdipoR1 and AdipoR2) in chicken ovary: potential role in ovarian steroidogenesis

Adiponectin and its receptors (AdipoR1 and AdipoR2) mRNAs are expressed in various chicken tissues including ovary. However, the cellular expression and the role of adiponectin system have never been investigated in chicken ovary. Here, we have shown that the level of adiponectin mRNA is about 10- to 30-fold higher (p < 0.001) in theca cells than in granulosa cells from each hierarchical yellow follicle studied (F4–F1). In contrast, the level of AdipoR1 mRNA expression was about two-fold lower in theca cells than in granulosa cells (p < 0.05) whereas those of AdipoR2 was similar in both ovarian cells. Whereas expression of adiponectin mRNA increased with follicular differentiation in theca cells, it decreased in granulosa cells. In contrast, mRNA expression of AdipoR1 and AdipoR2 in both theca and granulosa cells remained stable during yellow follicle development. To determine whether adiponectin is involved in the ovarian steroidogenesis, LH (100 ng/ml)-, FSH (100 ng/ml)- and IGF-1 (100 ng/ml)-induced progesterone production was measured in absence or presence of human recombinant adiponectin (10 μg/ml) for 36 h in cultured granulosa cells from F1, F2 and mixed F3 and F4 follicles. In absence of LH, FSH and IGF-1, adiponectin treatment had no effects on progesterone production whatever vitollegenic follicle studied. However, it increased by about two-fold IGF-1-induced progesterone secretion in F2 and F3/4 follicles whereas it halved progesterone production in response to gonadotropins (LH and FSH) in F3/4 follicles. Thus, in chicken, adiponectin, mainly expressed in theca cells, could exert paracrine or autocrine effect on the ovarian steroidogenesis.     

Measurement of plasma leucine flux in rainbow trout (Salmo gairneri R.) using osmotic pump. Preliminary investigations on influence of diet

A method for the direct measurement of plasma amino acid flux, in rainbow trout, using the continuous infusion of L-[U-¹⁴C]-leucine with ALZET mini-osmotic pumps implanted into the peritoneal cavity, was developed. The fish were fed successively on three different diets (a commercial control diet, a semi-purified diet and a purified diet) during the 4 weeks of experiment. The amounts of radioactivity in the free pool and the protein of both the plasma and skin mucus were measured in these fish. The total flux of leucine was calculated either from the specific activity of leucine in the plasma (61.8 mg leucine. 100 g^-1.d^-1) or from the amounts of labelled and unlabelled leucine flowing into the skin mucus protein (61.5 mg leucine. 100g^-1.day^-1). The total plasma flux was not affected by changes in the diet. The contributions of total leucine oxidation and whole body protein turnover to plasma leucine flux (80% and 20% respectively) were estimated in fish fed the semi-purified diet.     

Comparison and differentiation of Wheat Yellow Mosaic Virus(WYMV), Wheat Spindle Streak Mosaic Virus (WSSMV) and Barley Yellow Mosaic Virus (BaYMV) isolates using WYMV monoclonal antibodies

Twelve monoclonal antibodies (MAbs) were obtained by immunizing mice with a French isolate (F1) of wheat yellow mosaic virus (WYMV). Three of these (3D12, 2C1, 6C3) belong to the IgM class and the nine others to the IgG class (3D8, 3H1, 2B8, 1F2, 3C10, 4F12, 3H9, 1G5, 54). In antigen-coated plate (ACP) ELISA and indirect double antibody sandwich (IDAS) ELISA, all MAbs recognize the WYMV (F1) both in the form of purified particles and in wheat leaf extract. The analysis of numerous French isolates of WYMV shows a variable reactivity with MAbs 3D8, 3H1, 2B8, 3C10, 3H9 and 1G5 in IDAS — and ACP-ELISA. The Japanese isolate of WYMV and United States isolates of wheat spindle streak mosaic virus (WSSMV) were detected in IDAS- and ACP-ELISA by ten of the MAbs tested showing that the wheat bymoviruses originating from the three locations share a high epitopic homology. French isolates of barley yellow mosaic virus (BaYMV; pathotypes 1 and 2) were only detected in ACP-ELISA with MAbs 6C3, 3D8, 3H1 and 2B8 whereas the two Japanese strains (I-1, II-1) of MaYMV were recognized with these and also with that of 3C10. In IDAS-ELISA, the two Japanese strains were clearly detected by MAbs, 6C3, 3D8, 3H1, 1F2, 3C10 and 1G5 and the British and Belgian (pathotype 2) isolates only by that of 6C3. Only the Japanese strain of BaYMV, 1-1 could be detected with MAb 3H9 in this ELISA system.