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1.
Endothelial progenitor cells (EPC) participate in revascularization and angiogenesis. EPC can be cultured in vitro from mononuclear cells of peripheral blood, umbilical cord blood or bone marrow; they also can be transdifferentiated from mesenchymal stem cells (MSC). We isolated EPCs from Wharton's jelly (WJ) using two methods. The first method was by obtaining MSC from WJ and characterizing them by flow cytometry and their adipogenic and osteogenic differentiation, then applying endothelial growth differentiating media. The second method was by direct culture of cells derived from WJ into endothelial differentiating media. EPCs were characterized by morphology, Dil-LDL uptake/UEA-1 immunostaining and testing the expression of endothelial markers by flow cytometry and RT-PCR. We found that MSC derived from WJ differentiated into endothelial-like cells using simple culture conditions with endothelium induction agents in the medium.  相似文献   
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The asexual nature of the first cortical reorganization of conjugation in Stylonychia was analyzed by comparing the effect of amputation performed at different stages of early conjugation to that performed on vegetative cells at different stages of the cell cycle. Amputation of vegetative cells delineated a point of commitment to binary fission at 0.51–0.57 of the cell cycle. Cells amputated before this point were induced to undergo the regenerative mode of asexual development, but those amputated after this point continued with binary fission. In parallel, during conjugation a similar commitment was made around the time of formation of tight mating-pairs: early conjugants amputated around this time might undergo regeneration, and those operated on after this stage continued with the first cortical reorganization as in typical conjugants. The two mates of a pair might differ in their response to amputation, suggesting that the timing of commitment to the first cortical reorganization is not related to the events of conjugation, but rather is individually determined in the vegetative cycle of the cells before they pair up in mating. These observations provide support for the notion that the first cortical reorganization of conjugants is homologous to the asexual mode of cortical development in dividers, according to the theory of developmental heterochrony in the sexual reproduction of hypotrichs. The timing of commitment to the first cortical reorganization was found to temporally correlate with the entrance of the micronuclei into meiosis. Since the first cortical reorganization can proceed without the micronucleus, this raises the possibility that initiation of micronuclear meiosis is closely coupled with, and may be determined by, the commitment to the first cortical reorganization.  相似文献   
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对多种生物薄样品和标样进行电子探针X射线能谱显微定量分析,分别以电子束轰击后样品的O Kα峰计数和介于4.2-6.2keV区间的连续X-射线计数变化监测质量损失,结果显示样品O Kα峰计数减少幅度大于连续X-射线计数减少幅度,在相同的分析条件下,各样品质量损失程度不相同(P<0.05)。培养肝癌细胞冷冻干燥超薄切片、明胶冷冻干燥超薄切片、BSA薄膜、氨基塑料超薄切片、红细胞冷冻干燥超薄切片和卵黄高磷蛋白薄膜样品的质量损失分别为33%、28%、26%、18%、13%和13%,以上结果提示:以O Kα峰计数的减少监测样品的质量损失较敏感,在进行生物薄试样定量EPMA时应对各样品的质量损失进行相应校正。  相似文献   
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Liver fibrosis is a growing global health problem characterized by excess deposition of fibrillar collagen, and activation of hepatic stellate cells (HSCs). Adiponectin is known to possess anti-fibrotic properties; however a high physiological concentration and multiple forms circulating in blood prohibit clinical use. Recently, an adiponectin-like small synthetic peptide agonist (ADP355: H-DAsn-Ile-Pro-Nva-Leu-Tyr-DSer-Phe-Ala-DSer-NH2) was synthesized for the treatment of murine breast cancer. The present study was designed to evaluate the efficacy of ADP355 as an anti-fibrotic agent in the in vivo carbon tetrachloride (CCl4)-induced liver fibrosis model. Liver fibrosis was induced in eight-week old male C57BL/6J mice by CCl4-gavage every other day for four weeks before injection of a nanoparticle-conjugated with ADP355 (nano-ADP355). Control gold nanoparticles and nano-ADP355 were administered by intraperitoneal injection for two weeks along with CCl4-gavage. All mice were sacrificed after 6 weeks, and serum and liver tissue were collected for biochemical, histopathologic and molecular analyses. Biochemical studies suggested ADP355 treatment attenuates liver fibrosis, determined by reduction of serum aspartate aminotransferase (AST), alanine aminotransferase ALT) and hydroxyproline. Histopathology revealed chronic CCl4-treatment results in significant fibrosis, while ADP355 treatment induced significantly reversed fibrosis. Key markers for fibrogenesis–α-smooth muscle actin (α-SMA), transforming growth factor-beta1 (TGF-β1), connective tissue growth factor (CTGF), and the tissue inhibitor of metalloproteinase I (TIMP1) were also markedly attenuated. Conversely, liver lysates from ADP355 treated mice increased phosphorylation of both endothelial nitric oxide synthase (eNOS) and AMPK while AKT phosphorylation was diminished. These findings suggest ADP355 is a potent anti-fibrotic agent that can be an effective intervention against liver fibrosis.  相似文献   
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Craniometric data of nine characters from 260 skulls of Oryctolagus cuniculus from western Europe and northern Africa were gathered to examine phenotypic variation in size, using both univariate and multivariate analyses. Although animals from the northern part of Europe were found to be larger than those from southern Europe, variation in size occurred in a continuous cline. Skull size was positively correlated with latitude and negatively correlated with ambient temperature. On the basis of skull morphology, there is no evidence for separation of O. cuniculus into the two or more subspecies commonly described. Further data, particularly from genetic material, are required to clarify the taxonomic status of the rabbit in Europe.  相似文献   
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Net ecosystem productivity (NEP) was continuously measured using the eddy covariance (EC) technique from 2003 to 2005 at three forest sites of ChinaFLUX. The forests include Changbaishan temperate mixed forest (CBS), Qianyanzhou subtropical coniferous plantation (QYZ), and Dinghushan subtropical evergreen broad‐leaved forest (DHS). They span wide ranges of temperature and precipitation and are influenced by the eastern Asian monsoon climate to varying extent. In this study, we estimated ecosystem respiration (RE) and gross ecosystem productivity (GEP). Comparison of ecosystem carbon exchange among the three forests shows that RE was mainly determined by temperature, with the forest at CBS exhibiting the highest temperature sensitivity among the three ecosystems. The RE was highly dependent on GEP across the three forests, and the ratio of RE to GEP decreased along the North–South Transect of Eastern China (NSTEC) (i.e. from the CBS to the DHS), with an average of 0.77 ± 0.06. Daily GEP was mainly influenced by temperature at CBS, whereas photosynthetic photon flux density was the dominant factor affecting the daily GEP at both QYZ and DHS. Temperature mainly determined the pattern of the interannual variations of ecosystem carbon exchange at CBS. However, water availability primarily controlled the interannual variations of ecosystem carbon exchange at QYZ. At DHS, NEP attained the highest values at the beginning of the dry seasons (autumn) rather than the rainy seasons (summer), probably because insufficient radiation and frequent fog during the rainy seasons hindered canopy photosynthesis. All the three forest ecosystems acted as a carbon sink from 2003 to 2005. The annual average values of NEP at CBS, QYZ, and DHS were 259 ± 19, 354 ± 34, and 434 ± 66 g C m−2 yr−1, respectively. The slope of NEP that decreased with increasing latitude along the NSTEC was markedly different from that observed on the forest transect in the European continent. Long‐term flux measurements over more forest ecosystems along the NSTEC will further help verify such a difference between the European forest transect and the NSTEC and provide insights into the responses of ecosystem carbon exchange to climate change in China.  相似文献   
10.

Background

Cooperation and conflict in social insects are closely linked to the genetic structure of the colony. Kin selection theory predicts conflict over the production of males between the workers and the queen and between the workers themselves, depending on intra-colonial relatedness but also on other factors like colony efficiency, sex ratios, cost of worker reproduction and worker dominance behaviour. In most bumblebee (Bombus) species the queen wins this conflict and often dominates male production. However, most studies in bumblebees have been conducted with only a few selected, mostly single mated species from temperate climate regions. Here we study the genetic colony composition of the facultative polyandrous neotropical bumblebee Bombus wilmattae, to assess the outcome of the queen-worker conflict over male production and to detect potential worker policing.

Results

A total of 120 males from five colonies were genotyped with up to nine microsatellite markers to infer their parentage. Four of the five colonies were queen right at point of time of male sampling, while one had an uncertain queen status. The workers clearly dominated production of males with an average of 84.9% +/- 14.3% of males being worker sons. In the two doubly mated colonies 62.5% and 96.7% of the male offspring originated from workers and both patrilines participated in male production. Inferring the mother genotypes from the male offspring, between four to eight workers participated in the production of males.

Conclusions

In this study we show that the workers clearly win the queen-worker conflict over male production in B. wilmattae, which sets them apart from the temperate bumblebee species studied so far. Workers clearly dominated male production in the singly as well the doubly mated colonies, with up to eight workers producing male offspring in a single colony. Moreover no monopolization of reproduction by single workers occurred.  相似文献   
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