Variable survival across low pH gradients in freshwater fish species

A series of 14 day experiments was conducted on five common New Zealand fish species (redfin bully Gobiomorphus huttoni, inanga Galaxias maculatus, brown trout Salmo trutta, longfin eel Anguilla dieffenbachii and koaro Galaxias brevipinnis) to assess the effect of pH on survival and changes in body mass. No species survived in water of pH <4 although there was 100% survival of all adults at pH 4·5, G. maculatus larvae were also tested and had high mortality at this pH. Results suggest that adults are tolerant of low‐pH waters; however, successful remediation of anthropogenically acidified streams will require an understanding of the susceptibility to low pH on different life cycle stages.     

凋落物输入改变对亚热带两种米槠次生林土壤酶活性的影响

酶在土壤有机质分解中起重要作用。为深入了解全球变化背景下森林凋落物产量的改变对森林生态系统过程的影响, 以亚热带米槠(Castanopsis carlesii)人促更新次生林(米槠人促林)和米槠次生林为研究对象, 设置凋落物加倍(DL)、凋落物去除(NL)和对照(CT) 3种处理, 探讨土壤6种胞外酶活性的变化。研究结果表明: 米槠次生林中土壤纤维素水解酶(CBH)、β-N-乙酰氨基葡萄糖苷酶(NAG)、酚氧化酶(PhOx)和过氧化酶(PerOx)活性高于米槠人促林, 而酸性磷酸酶(AP)和β-葡萄糖苷酶(βG)活性没有差异; NL和DL处理均降低了两种不同更新方式森林土壤的AP、βG和NAG活性, CBH和PerOx活性均无显著变化, 而PhOx活性仅在DL处理后降低; 除NAG活性外, 米槠人促林的AP、βG、PhOx活性在凋落物处理后下降的幅度均高于次生林; Pearson相关分析和冗余分析表明, 土壤酶活性与土壤含水量、碳(C)、氮(N)含量和微生物生物量碳(MBC)、氮(MBN)含量显著相关。因此, 凋落物输入的改变(无论增加和减少), 引起了土壤含水量、C、N以及MBC和MBN含量的下降, 进而可能会导致亚热带米槠次生林和米槠人促林土壤某些胞外酶(如AP、βG和NAG)活性降低。从土壤酶活性角度看, 米槠次生林比米槠人促林更有利于亚热带森林生态系统C、N养分循环。     

A conserved helix-unfolding motif in the naturally unfolded proteins

Among the naturally unfolded proteins there are many polypeptides that retain an extended conformation in the absence of any apparent signal. Using sequence alignment and secondary structure prediction tools, a conserved (LS/SL)(D/E)(D/E)(D/E)X(E/D) motif is uncovered in the vicinity of the N-terminus of their unfolded helices. A comparison of these data with published observations allows one to propose that the (LS/SL)(D/E)(D/E)(D/E)X(E/D) motif is a helix-unfolding signal. Furthermore, the strong similarity between this motif and the STXXDE casein kinase II phosphorylation site suggests a regulatory mechanism for the naturally unfolded proteins within the cell.     

Changing concepts in plant hormone action

Summary A plant hormone is not, in the classic animal sense, a chemical synthesized in one organ, transported to a second organ to exert a chemical action to control a physiological event. Any phytohormone can be synthesized everywhere and can influence different growth and development processes at different places. The concept of physiological activity under hormonal control cannot be dissociated from changes in concentrations at the site of action, from spatial differences and changes in the tissue's sensitivity to the compound, from its transport and its metabolism, from balances and interactions with the other phytohormones, or in their metabolic relationships, and in their signaling pathways as well. Secondary messengers are also involved. Hormonal involvement in physiological processes can appear through several distinct manifestations (as environmental sensors, homeostatic regulators and spatio-temporal synchronizers, resource allocators, biotime adjusters, etc.), dependent on or integrated with the primary biochemical pathways. The time has also passed for the hypothesized ‘specific’ developmental hormones, rhizocaline, canlocaline, and florigen: root, stem, and flower formation result from a sequential control of specific events at the right places through a coordinated control by electrical signals, the known phytohormones and nonspecific molecules of primary and secondary metabolism, and involve both cytoplasmic and apoplastic compartments. These contemporary views are examined in this review.     

Transfer of genome fragments in double infection of E. coli with T5 and phi X174 bacteriophages.

Double infection of Escherichia coli by two DNA phages (phi X174 and T5) resulted in encapsidation into T5 particles of T5 DNA containing linked fragments of phi X174 DNA. The phi X474 sequences in T5 "hybrid" DNA were detected by RNA-DNA hybridization.     

13C-NMR spectroscopy of biflavanoids

The ¹³C-NMR spectra of nine naturally occurring CC linked biflavanoids have been assigned. The signals for the carbon atoms I-6, I-8, II-6, and II-8 appear in the region 90.0 ppm to 105.0 ppm. On the basis of the chemical shifts of these signals and their multiplicities in the off-resonance spectra, it is possible to determine the interflavonoid linkage in biflavanoids, provided that the A ring is involved. The level of oxidation of the ring C can be readily determined by a consideration of the chemical shift value of the carbonyl resonances. The position of the methoxyl substitution can also be inferred.     

In vivo formation of Plasmodium falciparum ribosomal stalk — A unique mode of assembly without stable heterodimeric intermediates

Background

The ribosomal stalk composed of P-proteins constitutes a structure on the large ribosomal particle responsible for recruitment of translation factors and stimulation of factor-dependent GTP hydrolysis during translation. The main components of the stalk are P-proteins, which form a pentamer. Despite the conserved basic function of the stalk, the P-proteins do not form a uniform entity, displaying heterogeneity in the primary structure across the eukaryotic lineage. The P-proteins from protozoan parasites are among the most evolutionarily divergent stalk proteins.

Methods

We have assembled P-stalk complex of Plasmodium falciparum in vivo in bacterial system using tricistronic expression cassette and provided its characteristics by biochemical and biophysical methods.

Results

All three individual P-proteins, namely uL10/P0, P1 and P2, are indispensable for acquisition of a stable structure of the P stalk complex and the pentameric uL10/P0-(P1-P2)₂ form represents the most favorable architecture for parasite P-proteins.

Conclusion

The formation of P. falciparum P-stalk is driven by trilateral interaction between individual elements which represents unique mode of assembling, without stable P1–P2 heterodimeric intermediate.

General significance

On the basis of our mass-spectrometry analysis supported by the bacterial two-hybrid assay and biophysical analyses, a unique pathway of the parasite stalk assembling has been proposed. We suggest that the absence of P1/P2 heterodimer, and the formation of a stable pentamer in the presence of all three proteins, indicate a one-step formation to be the main pathway for the vital ribosomal stalk assembly, whereas the P2 homo-oligomer may represent an off-pathway product with physiologically important nonribosomal role.     

北京动物园大熊猫繁殖记录

北京动物园在三十年中,共繁殖大熊猫28胎（其中双胎18次）,产仔46只,成活21只,成活率为45．65％,为大熊猫的迁地保护作出了杰出的贡献。1963年第一次在人工饲养下自然繁殖成功大熊猫“明明”;1978年第一次用人工授精方法繁殖成功大熊猫“元晶”;1980年第一次以纯超低温保存的大熊猫冷冻精液人工授精成功产下二仔;1987年第一次在人工饲养下繁殖出子三代;1990年第一次实现不同地理位置的大熊猫自然交配繁殖成功幼仔“亚庆”;1992年第一次繁殖成功大熊猫人工授精第三代幼仔“京京”;1992年第一次以人工授精繁殖长大的雄性大熊猫自然交配成功繁殖“永明”和“永亮”;1992～1993年第一次以人工哺育的方法使未食母乳的大熊猫幼仔“永亮”成活;1993年第一次达到1992年所产的3仔全部成活,成活率为100％。     

Vaccination strategies in tauopathies and synucleinopathies

Vaccination therapies constitute potential treatment options in neurodegenerative disorders such as Alzheimer disease or Parkinson disease. While a lot of research has been performed on vaccination against extracellular amyloid β, the focus recently shifted toward vaccination against the intracellular proteins tau and α‐synuclein, with promising results in terms of protein accumulation reduction. In this review, we briefly summarize lessons to be learned from clinical vaccination trials in Alzheimer disease that target amyloid β. We then focus on tau and α‐synuclein. For both proteins, we provide important data on protein immunogenicity, and put them into context with data available from both animals and human vaccination trials targeted at tau and α‐synuclein. Together, we give a comprehensive overview about current clinical data, and discuss associated problems.

     

Increased inferior olivary neuron and cerebellar granule cell numbers in transgenic mice overexpressing the human Bcl-2 gene

Neuron-target interactions during development are critical for determining the final numbers of neurons in the nervous system. To investigate the role of Purkinje cells and programmed cell death in the regulation of afferent neuron numbers, we have counted olivary neurons and granule cells in two lines of transgenic mice (NSE73a and NSE71) that overexpress a human gene for bcl-2 (Hu-bcl-2) in Purkinje cells and olivary neurons, but not in granule cells. Bcl-2 overexpression in vivo reduces naturally occurring neuronal cell death and cell death following axotomy, target removal, or ischemia. Olivary neuron numbers in NSE73a and NSE71 transgenic mice are significantly increased compared to controls by 28% and 27%, respectively, while granule cell numbers are only increased in NSE73a mice (29% above controls). We have previously shown that Purkinje cell number is increased by 43% in NSE73a transgenics and by 23% in NSE71 transgenics. The ratio of Purkinje cells to olivary neurons is not significantly different between the control and transgenic mice, while the ratio of granule cells to Purkinje cells is significantly decreased in the NSE71 transgenic mice compared to controls and NSE73a transgenics. The increased numbers of olivary neurons suggest that bcl-2 overexpression rescues these neurons from programmed cell death. The increase in granule cell number in only one transgenic line is discussed with respect to hypotheses that Purkinje cells regulate both granule cell progenitor proliferation and the survival of differentiated granule cells. © 1997 John Wiley & Sons, Inc. J Neurobiol 32: 502–516, 1997