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941.
Tingey DT Lee EH Phillips DL Rygiewicz PT Waschmann RS Johnson MG Olszyk DM 《Plant, cell & environment》2007,30(11):1400-1410
We investigated the effects of elevated CO(2) (EC) [ambient CO(2) (AC) + 190 ppm] and elevated temperature (ET) [ambient temperature (AT) + 3.6 degrees C] on net ecosystem exchange (NEE) of seedling Douglas fir (Pseudotsuga menziesii) mesocosms. As the study utilized seedlings in reconstructed soil-litter-plant systems, we anticipated greater C losses through ecosystem respiration (R(e)) than gains through gross photosynthesis (GPP), i.e. negative NEE. We hypothesized that: (1) EC would increase GPP more than R(e), resulting in NEE being less negative; and (2) ET would increase R(e) more than GPP, resulting in NEE being more negative. We also evaluated effects of CO(2) and temperature on light inhibition of dark respiration. Consistent with our hypothesis, NEE was a smaller C source in EC, not because EC increased photosynthesis but rather because of decreased respiration resulting in less C loss. Consistent with our hypothesis, NEE was more negative in ET because R(e) increased more than GPP. The light level that inhibited respiration varied seasonally with little difference among CO(2) and temperature treatments. In contrast, the degree of light inhibition of respiration was greater in AC than EC. In our system, respiration was the primary control on NEE, as EC and ET caused greater changes in respiration than photosynthesis. 相似文献
942.
Thelander M Nilsson A Olsson T Johansson M Girod PA Schaefer DG Zrÿd JP Ronne H 《Plant molecular biology》2007,64(5):559-573
The yeast Snf1, animal AMPK, and plant SnRK1 protein kinases constitute a family of related proteins that have been proposed
to serve as metabolic sensors of the eukaryotic cell. We have previously reported the characterization of two redundant SnRK1
encoding genes (PpSNF1a and PpSNF1b) in the moss Physcomitrella patens. Phenotypic analysis of the snf1a snf1b double knockout mutant suggested that SnRK1 is important for the plant’s ability to recognize and adapt to conditions of
limited energy supply, and also suggested a possible role of SnRK1 in the control of plant development. We have now used a
yeast two-hybrid system to screen for PpSnf1a interacting proteins. Two new moss genes were found, PpSKI1 and PpSKI2, which encode highly similar proteins with homologues in vascular plants. Fusions of the two encoded proteins to the green
fluorescent protein localize to the nucleus. Knockout mutants for either gene have an excess of gametophores under low light
conditions, and exhibit reduced gametophore stem lengths. Possible functions of the new proteins and their connection to the
SnRK1 kinase are discussed. 相似文献
943.
Denis-Quanquin S Lamouroux L Lougarre A Mahéo S Saves I Paquereau L Demange P Fournier D 《Journal of biotechnology》2007,131(3):223-230
Construction of synthetic genes is today the most elegant way to optimize the heterologous expression of a recombinant protein. However, the selection of positive clones that incorporate the correct synthetic DNA fragments is a bottleneck as current methods of gene synthesis introduce 3.5 nucleotide deletions per kb. Furthermore, even when all predictable optimizations for protein production have been introduced into the synthetic gene, production of the protein is often disappointing: protein is produced in too low amounts or end up in inclusion bodies. We propose a strategy to overcome these two problems simultaneously by cloning the synthetic gene upstream of a reporter gene. This permits the selection of clones devoid of frame-shift mutations. In addition, beside nucleotide deletion, an average of three non-neutral mutations per kb are introduced during gene synthesis. Using a reporter protein downstream of the synthetic gene, allows the selection of clones with random mutations improving the expression or the folding of the protein of interest. The problem of errors found in synthetic genes is then turned into an advantage since it provides polymorphism useful for molecular evolution. The use of synthetic genes appears as an alternative to the error-prone PCR strategy to generate the variations necessary in protein engineering experiments. 相似文献
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948.
Henry SL Concannon MJ Kaplan PA Diaz-Arias AA 《Plastic and reconstructive surgery》2007,120(1):80-8; discussion 89-90
949.
Murai T Mohamed M Bernard H Mahedi PA Saburi R Higashi S 《Primates; journal of primatology》2007,48(2):117-121
Successful or unsuccessful female transfers were observed seven times during a 32-month field study of proboscis monkeys (Nasalis larvatus) inhabiting a riverine forest along a tributary of the Kinabatangan River, Sabah, Malaysia. In all cases, the females voluntarily
left their own groups and immediately joined with another one. When adult females tried to shift to other groups, adult males
called them back to their own groups, but appeared to be indifferent to subadult females. When the adult females returned,
the males never attacked the females physically, but instead often emitted herding sounds to them. One subadult female was
repelled by a resident adult female. When one adult female transferred into a new one-male group, she left her behind son
in an all-male group. The number of females often fluctuated in most study groups, with this fluctuation being more prominent
among subadult females than adult females. It is likely that female transfer in proboscis monkeys is not a rare occurrence
and that it is especially common among sub-adult females. 相似文献
950.
Upper-to-lower limb proportions of Homo habilis are often said to be more ape-like than those of its reputed ancestor, Australopithecus afarensis. Such proportions would either imply multiple evolutionary reversals or parallel development of a relatively short upper limb in A. afarensis and later Homo. However, assessments of limb proportions are complicated by the fragmentary nature of the two known H. habilis skeletons, OH 62 and KNM-ER 3735. Initially, KNM-ER 3735 was compared to A.L. 288-1 (A. afarensis) using a single modern human and chimpanzee as reference. Here, based on a larger comparative sample, we find that the relative size of the distal humerus, radial head, and shaft of both KNM-ER 3735 and A.L. 288-1 lie within the range of variation of modern humans, whereas their sacra are small as is the case for all early hominids. In addition, their manual phalanges are similar in having a gracile base but robust midshaft. Contrary to earlier studies, the fossils are not differentiable from each other statistically with respect to all features listed above. On the other hand, they differ in robusticity of the scapular spine and relative length of the radial neck. An exact randomization test suggests only a very low probability of finding a similar degree of difference within a single species of extant hominoids. In contrast to the consensus view, we conclude that A.L. 288-1 had a short, human-like forearm, whereas KNM-ER 3735 possessed a distinctly longer forearm and more powerful shoulder girdle. This interpretation fits with earlier conclusions that suggested human-like humerofemoral proportions but chimpanzee-like brachial proportions for Homo habilis. Thus, the scenario of a unidirectional, progressive change in limb proportions within the hominid lineage is not supported by our work. 相似文献