Semen biology of vendace (<Emphasis Type="Italic">Coregonus albula</Emphasis> L.)

The objective of this study was to describe the morphometry and motility parameters of vendace (Coregonus albula) spermatozoa. Morphometric parameters of vendace sperm head and tail were of values similar to rainbow trout. The effects of pH, sodium, potassium and calcium ion concentrations on computer-assisted sperm analysis (CASA) sperm motility characteristics were tested. Vendace sperm was motile in a wide pH range of 6.0–10.5 with the optimum pH established at 9.0. Increases in potassium and calcium ions caused decreases in the percentage of motile sperm. The CASA parameters and erratic sperm movement pattern of vendace spermatozoa were similar to whitefish (C. lavaretus) sperm motility, suggesting that there is a coregonid-specific sperm motility pattern.     

Application of macroinvertebrate multimetrics as a measure of the impact of anthropogenic modification of spring habitats

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The use of bromelain as a feed additive in fish diets: Growth performance,intestinal morphology,digestive enzyme and immune response of juvenile Sterlet (Acipenser ruthenus)

Bromelain is a proteolytic enzyme extracted from Ananas comosus and has great potential to affect several physiological functions. The current study examined the effect of bromelain added to commercial feed at concentrations of 0 g (control), 10 g (B1) and 20 g (B2) per kg diet on growth, feed utilization, intestinal morphology, digestive enzyme and immune response of juvenile Sterlet (Acipenser ruthenus) for 56 days. At the end of this experiment, the highest final body weight was detected in fish fed diet of B2 compared to control. The protein content of whole fish was higher in fish fed diet of B1 and B2, but the content of calcium, iron, copper and zinc was noted lower in fillets of fish fed diet of B1 and B2. Supplementation with bromelain significantly increased the height of mucosal folds, enterocytes and the supranuclear zone of the epithelial cells compared to control diet. The enzymatic activity of lipase and pepsin was significantly (p < 0.05) higher in fish fed diet of B1 and B2. The highest activity of lysozyme, total protein level and total immunoglobulin and the proliferative activity of T and B cells were detected in fish fed diet of B2 compared to control, where no significant (p > 0.05) difference was found in ceruloplasmin, metabolic activity of spleen macrophages and potential killing activity of spleen phagocytes between different treatments.     

Calcium deficiency and gibberellic acid enhance susceptibility of pumpkin and sunflower seedlings to Sclerotinia sclerotiorum infection

Pumpkin (Cucurbita pepo L.) and sunflower (Helianthus annuus L.) seedlings were grown in culture deficient in calcium and inoculated with Sclerotinia sclerotiorum (Lib.) de Bary. Three days after inoculation the seedlings showed a susceptibility to the pathogen that was inversely proportional to the calcium content of the nutrient solution. Plants treated with gibberellic acid (GA₃) became more susceptible to infection by S. sclerotiorum. Increased addition of GA₃ resulted in increases in infection both in rate and severity. Sunflower was more susceptible to the pathogen than was pumpkin. GA₃ treatment consistently decreased the calcium content in both species. The effect of calcium deficiency on infection by S. sclerotiorum was greatly amplified by GA₃ addition.     

Drought in the forest breaks plant–fungi interactions

European Journal of Forest Research - Drought in the forest is not only a prolonged state of water shortage, but also an occasion where interactions between plants and fungi are affected. Water...     

Assessment of 137Cs and 239,240Pu Distribution in Forest Soils of the Opole Anomaly

Distribution of ¹³⁷Cs and ^239,240Pu in the forest soils horizons of the Opole Anomaly was established. Gamma and alpha spectrometry was used for determination of these isotopes. It was found that the ¹³⁷Cs activity was approx. 1,000 times higher than that of ^239,240Pu. The highest activities of both radioisotopes were found close to the boundary region in soil profile where the organic horizon turns into the inorganic one. Cluster analysis did not clearly indicate the group’s existence in data in respect to ¹³⁷Cs and ^239,240Pu activities and organic matter content. Distributions of ¹³⁷Cs and ^239,240Pu in soil horizons were non-normal but similar to each other. These distributions were substantially different from that one for organic matter content. The data were separated into two groups, for organic and inorganic soil horizons, respectively. Data transformation using Box–Cox formula was performed following by standardization. Mutual relationships between variables were investigated using ordinary and robust regression methods. Good correlation between ¹³⁷Cs and ^239,240Pu was found. No significant relationship between organic matter content and radioisotopes activity was asserted.     

PCR在安祖花和白鹤芋属间杂交种早期鉴定中的应用

采用以PCR技术为基础的tRNALeuCAA基因内序列细胞核标记和内部改写空间2(ITS2)序列2种方法对7个安祖花属的红鹤芋(Anthurium andraeanum)和白鹤芋属的矮小苞叶芋(Spathiphyllum wallissii)的属间杂交种进行鉴定.使用tRNALeuCAA基因内序列细胞标记共扩增出13个位点,供试杂种中均无父本特异性谱带出现,仅在1个杂种中出现新的谱带,表明该杂种为真正的属间杂种.ITS2序列法扩增出28个位点,杂种谱带表现3种类型:无父本特异性谱带出现;出现新谱带;既出现父本特异性谱带又出现新谱带.应用ITS2序列法有6个假定杂交种均被鉴定为真正的属间杂交种.试验结果表明,tRNALeuCAA基因内序列细胞核标记和内部改写空间2(ITS2)序列2种方法可以用于属间杂种的鉴定.     

Efficient deactivation of a model base pair via excited-state hydrogen transfer

We present experimental and theoretical evidence for an excited-state deactivation mechanism specific to hydrogen-bonded aromatic dimers, which may account, in part, for the photostability of the Watson-Crick base pairs in DNA. Femtosecond time-resolved mass spectroscopy of 2-aminopyridine clusters reveals an excited-state lifetime of 65 +/- 10 picoseconds for the near-planar hydrogen-bonded dimer, which is significantly shorter than the lifetime of either the monomer or the 3- and 4-membered nonplanar clusters. Ab initio calculations of reaction pathways and potential-energy profiles identify the mechanism of the enhanced excited-state decay of the dimer: Conical intersections connect the locally excited 1pipi* state and the electronic ground state with a 1pipi* charge-transfer state that is strongly stabilized by the transfer of a proton.