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991.
E. C. Bernard 《Journal of nematology》1984,16(2):194-203
Four new species of hoplolaimoid nematodes (Merlinius adakensis, Pratylenchoides megalobatus, Pratylenchus pratensisobrinus, and Pratylenchus ventroprojectus) are described from Adak Island in the Aleutian chain. M. adakensis n. sp. is separated from other species by body length (0.96-1.3 mm), stylet length (32-36 μm), number of tail annules (49-68), and c'' (3.1-4.1). P. megalobatus n. sp. differs from all known Pratylenchoides spp. by having a very long esophageal gland lobe (b'' = 2.4-3.3, overlap 3-6 times the body width). P. pratensisobrinus n. sp. closely resembles P. pratensis (de Man) Filipjev, but has a longer stylet (15-17 μm), a longer tail (c = 12-15; c'' = 2.8-3.7), and more tail annules (23-37). P. ventroprojectus n. sp. is distinguished by body length (392-475 μm), three lip annules, low and flattened cephalic capsule, and presence of terminal subventral projection. Pratylenchoides variabilis Sher, Helicotylenchus amplius Anderson &Eveleigh, and H. spitsbergensis Loof are also reported from Adak and Amchitka Islands. 相似文献
992.
在福建省药用植物资源调查中,陆续发现了福建省被子植物地理分布新记录属及种多个,经整理鉴定,本文继续报道了1个分布新记录科霉草科(Triuridaceae),2个分布新记录属喜荫草属(Sciaphila)和红葱属(Eleutherine),以及败酱叶菊芹 Erechtites valerianaefolia、大柱霉草 Sciaphila secundiflora、红葱 Eleutherine plicata和纤草Burmannia itoana等4个分布新记录种。标本存放于福建中医药大学药用植物标本室(FJTCM)。 相似文献
993.
首次记述采自中国云南省藤Calamus platyacanthoides上的尼泊尔扁片蜡蚧Platylecanium nepalense Takagi,1975.主要鉴别特征为:体缘光滑,气门刺4或5根,肛板合成菱形和无足.文中对雌成虫形态特征进行了详细描述及绘图. 相似文献
994.
Lesley Hughes 《Austral ecology》2003,28(4):423-443
Abstract This review summarizes recent research in Australia on: (i) climate and geophysical trends over the last few decades; (ii) projections for climate change in the 21st century; (iii) predicted impacts from modelling studies on particular ecosystems and native species; and (iv) ecological effects that have apparently occurred as a response to recent warming. Consistent with global trends, Australia has warmed ~0.8°C over the last century with minimum temperatures warming faster than maxima. There have been significant regional trends in rainfall with the northern, eastern and southern parts of the continent receiving greater rainfall and the western region receiving less. Higher rainfall has been associated with an increase in the number of rain days and heavy rainfall events. Sea surface temperatures on the Great Barrier Reef have increased and are associated with an increase in the frequency and severity of coral bleaching and mortality. Sea level rises in Australia have been regionally variable, and considerably less than the global average. Snow cover and duration have declined significantly at some sites in the Snowy Mountains. CSIRO projections for future climatic changes indicate increases in annual average temperatures of 0.4–2.0°C by 2030 (relative to 1990) and 1.0–6.0°C by 2070. Considerable uncertainty remains as to future changes in rainfall, El Niño Southern Oscillation events and tropical cyclone activity. Overall increases in potential evaporation over much of the continent are predicted as well as continued reductions in the extent and duration of snow cover. Future changes in temperature and rainfall are predicted to have significant impacts on most vegetation types that have been modelled to date, although the interactive effect of continuing increases in atmospheric CO2 has not been incorporated into most modelling studies. Elevated CO2 will most likely mitigate some of the impacts of climate change by reducing water stress. Future impacts on particular ecosystems include increased forest growth, alterations in competitive regimes between C3 and C4 grasses, increasing encroachment of woody shrubs into arid and semiarid rangelands, continued incursion of mangrove communities into freshwater wetlands, increasing frequency of coral bleaching, and establishment of woody species at increasingly higher elevations in the alpine zone. Modelling of potential impacts on specific Australian taxa using bioclimatic analysis programs such as bioclim consistently predicts contraction and/or fragmentation of species' current ranges. The bioclimates of some species of plants and vertebrates are predicted to disappear entirely with as little as 0.5–1.0°C of warming. Australia lacks the long‐term datasets and tradition of phenological monitoring that have allowed the detection of climate‐change‐related trends in the Northern Hemisphere. Long‐term changes in Australian vegetation can be mostly attributed to alterations in fire regimes, clearing and grazing, but some trends, such as encroachment of rainforest into eucalypt woodlands, and establishment of trees in subalpine meadows probably have a climatic component. Shifts in species distributions toward the south (bats, birds), upward in elevation (alpine mammals) or along changing rainfall contours (birds, semiarid reptiles), have recently been documented and offer circumstantial evidence that temperature and rainfall trends are already affecting geographic ranges. Future research directions suggested include giving more emphasis to the study of climatic impacts and understanding the factors that control species distributions, incorporating the effects of elevated CO2 into climatic modelling for vegetation and selecting suitable species as indicators of climate‐induced change. 相似文献
995.
Cytochrome bd is a terminal quinol:O2 oxidoreductase of respiratory chains of many bacteria. It contains three hemes, b558, b595, and d. The role of heme b595 remains obscure. A CO photolysis/recombination study of the membranes of Escherichia coli containing either wild type cytochrome bd or inactive E445A mutant was performed using nanosecond absorption spectroscopy. We compared photoinduced changes of heme d-CO complex in one-electron-reduced, two-electron-reduced, and fully reduced states of cytochromes bd. The line shape of spectra of photodissociation of one-electron-reduced and two-electron-reduced enzymes is strikingly different from that of the fully reduced enzyme. The difference demonstrates that in the fully reduced enzyme photolysis of CO from heme d perturbs ferrous heme b595 causing loss of an absorption band centered at 435 nm, thus supporting interactions between heme b595 and heme d in the di-heme oxygen-reducing site, in agreement with previous works. Photolyzed CO recombines with the fully reduced enzyme monoexponentially with τ ∼ 12 μs, whereas recombination of CO with one-electron-reduced cytochrome bd shows three kinetic phases, with τ ∼ 14 ns, 14 μs, and 280 μs. The spectra of the absorption changes associated with these components are different in line shape. The 14 ns phase, absent in the fully reduced enzyme, reflects geminate recombination of CO with part of heme d. The 14-μs component reflects bimolecular recombination of CO with heme d and electron backflow from heme d to hemes b in ∼ 4% of the enzyme population. The final, 280-μs component, reflects return of the electron from hemes b to heme d and bimolecular recombination of CO in that population. The fact that even in the two-electron-reduced enzyme, a nanosecond geminate recombination is observed, suggests that namely the redox state of heme b595, and not that of heme b558, controls the pathway(s) by which CO migrates between heme d and the medium. 相似文献
996.
Lin Yang Gao-Yi Tan Yu-Qiang Fu Jin-Hai Feng Min-Hong Zhang 《Comparative biochemistry and physiology. Toxicology & pharmacology : CBP》2010,151(2):204-208
In order to investigate the effects of acute heat stress and subsequent stress removal on function of hepatic mitochondrial respiration, production of reactive oxygen species (ROS) and lipid peroxidation in broiler chickens, 128 six-week-old broiler chickens were kept in a controlled-environment chamber. The broiler chickens were initially kept at 25 °C (relative humidity, RH, 70 ± 5%) for 6 d and subsequently exposed to 35 °C (RH, 70 ± 5%) for 3 h, then the heat stress was removed and the temperature returned to 25 °C (RH, 70 ± 5%). Blood and liver samples were obtained before heat exposure and at 0 (at the end of the three-hour heating episode, this group is also abbreviated as the HT group), 1, 2, 4, 8, 12 h after the stress was removed. The results showed that acute heat stress induced a significant production of ROS, function of the mitochondrial respiratory chain, antioxidative enzymes [superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px)] activity, and formation of malondialdehybe (MDA). Within the first 12 h after removal of the heat stress, the acute modification of the above parameters induced by heat stress gradually approached to pre-heat levels. The results of the present study suggest that acute exposure to high temperatures may depress the activity of the mitochondrial respiratory chain. This leads to over-production of ROS, which ultimately results in lipid peroxidation and oxidative stress. When the high temperature was removed, the production of ROS, mitochondrial respiratory function and oxidative injury that were induced by acute heat exposure gradually approached the levels observed before heating, in a time-dependent manner. 相似文献
997.
998.
A new genus and species of troglobitic buthid scorpion are described on the basis of a single specimen collected in Brazil. This is the first cavernicolous scorpion ever found in Brazil, and only the second to be found in South America. Some considerations on troglobitic scorpions are proposed. 相似文献
999.
Ethan P. White 《Ecology letters》2004,7(4):329-336
The species–time relationship (STR) is a macroecological pattern describing the increase in the observed species richness with the length of time censused. Understanding STRs is important for understanding the ecological processes underlying temporal turnover and species richness. However, accurate characterization of the STR has been hampered by the influence of sampling. I analysed STRs for 521 breeding bird survey communities. I used a model of sampling effects to demonstrate that the increase in richness was not due exclusively to sampling. I estimated the time scale at which ecological processes became dominant over sampling effects using a two‐phase model combining a sampling phase and either a power function or logarithmic ecological phase. These two‐phase models performed significantly better than sampling alone and better than simple power and logarithmic functions. Most community dynamics were dominated by ecological processes over scales <5 years. This technique provides an example of a rigorous, quantitative approach to separating sampling from ecological processes. 相似文献
1000.
The Korean species of the genus Eudorylas Aczél have been studied. A total of 16 species are arranged herein. Among them, E. paraappendiculatus sp. nov. is new to science, and E. nomurai Morakote et Yano, 1990 is newly recorded in the Korean fauna. 相似文献