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971.
We assessed diurnal variation of Chironomidae exuviae in two small upland streams in temperate Australia, during summer. Understanding
the diel periodicity of exuviae can be an important consideration for biomonitoring purposes or to investigate adult emergence
patterns. We collected 1,813 floating exuviae, comprising 54 taxa from four subfamilies, from flowing water using a drift
net. Unlike many northern hemisphere temperate studies, we observed that peak exuviae abundance (7.3 exuviae per m3) and taxon
richness (1.7 taxa per m3) occurred in the dusk and night hours, with the lowest numbers (0.9 exuviae per m3) and taxon richness
(0.6 taxa per m3) recorded in the late morning to early afternoon. We suggest that this could be an adaptation to avoid stressful
weather during the heat of summer days, or it could be to avoid visual predators. The numerically dominant taxa exhibited
peak abundance in the dusk/night samples which indicates predominant crepuscular/nocturnal patterns of adult emergence. This
pattern was consistent across both streams surveyed. Our taxon inventory rose steeply during the first 24-h occasion, then
at a reduced rate during the second and third days of sampling. For flowing water collections of exuviae that utilise drift-netting,
we suggest that sampling at all sites includes at least three 24-h cycles and avoids periods of heavy rainfall and increased
stream flow. 相似文献
972.
Primary production of aquatic macrophytes and their epiphytes in two shallow lakes (Peipsi and Võrtsjärv) in Estonia 总被引:1,自引:0,他引:1
In shallow lakes with large littoral zones, epiphytes and submerged macrophytes can make an important contribution to the total annual primary production. We investigated the primary production (PP) of phytoplankton, submerged macrophytes, and their epiphytes, from June to August 2005, in two large shallow lakes. The production of pelagic and littoral phytoplankton and of the dominant submerged macrophytes in the littoral zone (Potamogeton perfoliatus in Lake Peipsi and P. perfoliatus and Myriopyllum spicatum in Lake Võrtsjärv) and of their epiphytes was measured using a modified 14C method. The total PP of the submerged macrophyte area was similar in both lakes: 12.4 g C m?2 day?1 in Peipsi and 12.0 g C m?2 day?1 in Võrtsjärv. In Peipsi, 84.2% of this production was accounted for by macrophytes, while the shares of phytoplankton and epiphytes were low (15.6 and 0.16%, respectively). In Võrtsjärv, macrophytes contributed 58%, phytoplankton 41.9% and epiphytes 0.1% of the PP in the submerged macrophyte area. Epiphyte production in both lakes was very low in comparison with that of phytoplankton and macrophytes: 0.01, 5.04, and 6.97 g C m?2 day?1, respectively, in Võrtsjärv, and 0.02, 1.93, and 10.5 g C m?2 day?1, respectively, in Peipsi. The PP of the littoral area contributed 10% of the total summer PP of Lake Peipsi sensu stricto and 35.5% of the total summer PP of Lake Võrtsjärv. 相似文献
973.
Chien-Chih Chen Li-Wen Hsu Li-Tung Huang Tiao-Lai Huang 《Neurochemical research》2010,35(7):1098-1104
Neurotrophins, including the brain-derived neurotrophic factor (BDNF), are essential for regulating neuronal differentiation
in developing brains. BDNF and its receptor tyrosine kinase receptor B (TrkB) are involved in neuronal signaling, survival
and plasticity. Cyclosporine A (CsA) is a potent immunosuppressive agent which prevents allograft rejection in organ transplantation
and various immunological diseases. We investigated whether chronic administration of CsA decreases BDNF gene expression in
rats, and the influence of CsA on mRNA levels of TrkB receptors was also examined. For 30 days of CsA (10 mg/kg/day) administration,
the expression of BDNF and TrkB mRNA was significantly decreased in the hippocampus and midbrain, but there was no significant
difference in the cortex. CsA (0, 1, 5 10, 15 ug/ml) down-regulated BDNF and TrkB gene expression through cultured SH-SY5Y
cells, as did all-trans retinoic acid (ATRA), and there was no effect on cell viability. These experimental results indicate
that suppression of the BDNF and TrkB mRNA, protein level of BDNF expression in the hippocampus and midbrain may be related
to altered behavior observed following chronic administration of CsA. A common mechanism of adverse effects of CsA induced
depressive symptoms may involve neurotoxicity mediated by down-regulation of brain BDNF and TrkB. 相似文献
974.
口腔病灶被证实与许多系统性疾病的发生及发展有很大的相关关系,全身系统性疾病的治疗又会加重口腔病灶的感染,影响患者的生存质量,干扰系统性疾病的治疗,严重则造成全身感染。可能诱发或加重口腔病灶感染的系统性疾病治疗有:口服抗癫痫药物、免疫抑制剂等药物导致的药物性牙龈炎;恶性肿瘤放化疗并发的口腔黏膜炎;长期应用抑制肿瘤骨转移或预防骨质疏松的双磷酸盐造成的颌骨坏死;异基因造血干细胞移植后的口腔排异反应等。 相似文献
975.
Katherine J. Kayser-Bricker Matthew P. Glenn Sang Hoon Lee Said M. Sebti Jin Q. Cheng Andrew D. Hamilton 《Bioorganic & medicinal chemistry》2009,17(4):1764-1771
Akt has emerged as a critical target for the development of anti-cancer therapies. It has been found to be amplified, overexpressed, or constitutively activated in numerous human malignancies with oncogenesis derived from the simultaneous promotion of cell survival and suppression of apoptosis. A valuable alternative to the more common ATP-mimetic based chemotherapies is a substrate-mimetic approach, which has the potential advantage of inherent specificity of the substrate-binding pocket. In this paper we present the development of high affinity non-peptidic, substrate-mimetic inhibitors based on the minimum GSK3β substrate sequence. Optimization of initial peptidic leads resulted in the development of several classes of small molecule inhibitors, which have comparable potency to the initial peptidomimetics, while eliminating the remaining amino acid residues. We have identified the first non-peptidic substrate-mimetic lead inhibitors of Akt 29a–b, which have affinities of 17 and 12 μM, respectively. This strategy has potential to provide a useful set of molecular probes to assist in the validation of Akt as a potential target for anti-cancer drug design. 相似文献
976.
Cheng‐Hong Yang Yu‐Huei Cheng Li‐Yeh Chuang Hsueh‐Wei Chang 《Biotechnology progress》2009,25(3):745-753
To provide feasible primer sets for performing a polymerase chain reaction (PCR) experiment, many primer design methods have been proposed. However, the majority of these methods require a relatively long time to obtain an optimal solution since large quantities of template DNA need to be analyzed. Furthermore, the designed primer sets usually do not provide a specific PCR product size. In recent years, evolutionary computation has been applied to PCR primer design and yielded promising results. In this article, a memetic algorithm (MA) is proposed to solve primer design problems associated with providing a specific product size for PCR experiments. The MA is compared with a genetic algorithm (GA) using an accuracy formula to estimate the quality of the primer design and test the running time. Overall, 50 accession nucleotide sequences were sampled for the comparison of the accuracy of the GA and MA for primer design. Five hundred runs of the GA and MA primer design were performed with PCR product lengths of 150–300 bps and 500–800 bps, and two different methods of calculating Tm for each accession nucleotide sequence were tested. A comparison of the accuracy results for the GA and MA primer design showed that the MA primer design yielded better results than the GA primer design. The results further indicate that the proposed method finds optimal or near‐optimal primer sets and effective PCR products in a dry dock experiment. Related materials are available online at http://bio.kuas.edu.tw/ma‐pd/ . © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 相似文献
977.
The carotenoid synthetic genes, crtM and crtN, derived from Staphylococcus aureus, were introduced into B. subtilis, resulting in yellow pigmentation. Absorption maxima of pigments and MALDI-TOF mass spectrometry demonstrated that the pigmented
strain accumulated two C30 carotenoids, 4,4′-diapolycopene and 4,4′-diaponeurosporene. A survival test using H2O2 revealed that the pigmented strain was more resistant to oxidative stress than the strain harboring an empty-vector. These
findings indicate that B.
subtilis can produce carotenoids, and the strain accumulating the carotenoids, CarotenoBacillus, will become a basal host for production
of C30 carotenoids and evaluation of their antioxidative effects. 相似文献
978.
Georgi Z. Genchev Morten Källberg Gamze Gürsoy Anuradha Mittal Lalit Dubey Ognjen Perisic Gang Feng Robert Langlois Hui Lu 《Cell biochemistry and biophysics》2009,55(3):141-152
Efficient communication between the cell and its external environment is of the utmost importance to the function of multicellular
organisms. While signaling events can be generally characterized as information exchange by means of controlled energy conversion,
research efforts have hitherto mainly been concerned with mechanisms involving chemical and electrical energy transfer. Here,
we review recent computational efforts addressing the function of mechanical force in signal transduction. Specifically, we
focus on the role of steered molecular dynamics (SMD) simulations in providing details at the atomic level on a group of protein
domains, which play a fundamental role in signal exchange by responding properly to mechanical strain. We start by giving
a brief introduction to the SMD technique and general properties of mechanically stable protein folds, followed by specific
examples illustrating three general regimes of signal transfer utilizing mechanical energy: purely mechanical, mechanical
to chemical, and chemical to mechanical. Whenever possible the physiological importance of the example at hand is stressed
to highlight the diversity of the processes in which mechanical signaling plays a key role. We also provide an overview of
future challenges and perspectives for this rapidly developing field. 相似文献
979.
The chitosan with three-dimensional porous structure greatly increased the effective electrode surface for loading of platinum nanoparticles and promoted efficient electron transfer. The resulting biosensor had a response time (within 5 s) and a linear response from 6 μM to 4.2 mM glucose with a detection limit of 2 μM (S/N = 3). Moreover, the methodology can be applied for the immobilization of other enzymes. 相似文献
980.