神经反馈调节失衡与帕金森病(Parkinson's desease)

机体的各种组织、器官和系统能维持正常的生理功能,离不开各种形式的反馈调节,这些调节包括神经调节,体液调节和局部的自身调节。机体生理活动的调节在分子、细胞和系统的各种水平都存在,而且每种反馈调节都必须得到精确控制,否则将会引起各种疾病。帕金森病的产生就是大脑有关脑区兴奋和抑制的反馈调节失衡造成的,它为我们理解生命活动过程中的反馈调节机制提供了一个极为典型的有重要价值的模型。[第一段]     

'神马'菊花的离体保存及遗传稳定性

用添加不同蔗糖与甘露醇配比的培养基对切花菊品种＇神马＇（Jinba）试管苗进行离体保存,并对保存材料再生后代的遗传稳定性进行了研究.结果表明,在温度（23±2）℃、光照强度2 000～3 000 lx、光照时间12 h/d的培养条件下,MS＋0.3 mg·L^-1 6-BA＋0.1 mg·L^-1NAA培养基中分别添加10 g·L^-1蔗糖和10 g·L^-1甘露醇、10 g·L^-1蔗糖和20 g·L^-1甘露醇、20 g·L^-1蔗糖和20 g·L^-1甘露醇或30 g·L^-1蔗糖和10 g·L^-1甘露醇均能使菊花试管苗连续保存12个月,其中10 g·L^-1蔗糖和20 g·L^-1甘露醇、20 g·L^-1蔗糖和20 g·L^-1甘露醇组合处理保存12个月后成活率较高,分别达到50.00%和60.00%,且均保持最高的增殖倍数2.67.保存12个月的试管苗在增殖、生根培养基上均能正常恢复生长,且其再生后代的田间生物学性状、过氧化物酶（POD）及酯酶（EST）同工酶酶谱、ISSR扩增图谱与对照株无差异,保持了良好的遗传稳定性,说明利用上述方法保存＇神马＇种质是可行的.     

Simulation d'un plan d'expérience en océanographie: Effets de la dispersion des organismes sur l'erreur d'échantillonnage

Seven spatial dispersions of organisms, reflecting some constraints of various physical and biological factors of the pelagic environment were simulated on computer. The relationships between the sampling methods (tow length, net size), the pelagic population dispersion patterns, and the sampling error were investigated by computer simulation. Two categories of dispersions were identified: 1) random or relatively uniform dispersions of organisms (including Poisson, gradient, and negative contagous dispersions), characterized by an index of dispersion $\text{s}{}^2\text{m}\text{< 1.5}$; and 2) overdispersed distributions of swarming or clustering organisms (including positive contagion and centric aggregation dispersions), characterized by a value of $\text{s}{}^2\text{m}\text{> 1.5}$.The origin and size of the sampling errors as deduced from the analysis of variance change, considerably from one group of dispersions to the other. In the first case, the net size was dominant, whereas in the second case the tow length and patch size effects are more critical. In general, the precision of estimations decreases as the over-dispersion of organisms increases. The confidence limits, for a simple estimation of abundance, vary considerably with the spatial dispersion, ranging from narrow values for the relatively uniform dispersions to very large values for the overdispersed distributions. There is an increasing imprecision in the estimate of population abundance as the dispersion coefficient $\text{s}{}^2\text{m}$ increases.Analysis of coefficients of variation indicates that more precise estimates of abundance may be obtained if a practical sampling procedure is applied to a group of specific organisms. Furthermore, it is suggested that a simulated approach, performed prior to ocean sampling, permits the establishment of the optimal sampling procedure for the species under study.     

mTORC2 Signaling: A Path for Pancreatic β Cell's Growth and Function

The mechanistic target of rapamycin (mTOR) signaling pathway is an evolutionary conserved pathway that senses signals from nutrients and growth factors to regulate cell growth, metabolism and survival. mTOR acts in two biochemically and functionally distinct complexes, mTOR complex 1 (mTORC1) and 2 (mTORC2), which differ in terms of regulatory mechanisms, substrate specificity and functional outputs. While mTORC1 signaling has been extensively studied in islet/β-cell biology, recent findings demonstrate a distinct role for mTORC2 in the regulation of pancreatic β-cell function and mass. mTORC2, a key component of the growth factor receptor signaling, is declined in β cells under diabetogenic conditions and in pancreatic islets from patients with type 2 diabetes. β cell-selective mTORC2 inactivation leads to glucose intolerance and acceleration of diabetes as a result of reduced β-cell mass, proliferation and impaired glucose-stimulated insulin secretion. Thereby, many mTORC2 targets, such as AKT, PKC, FOXO1, MST1 and cell cycle regulators, play an important role in β-cell survival and function. This indicates mTORC2 as important pathway for the maintenance of β-cell homeostasis, particularly to sustain proper β-cell compensatory response in the presence of nutrient overload and metabolic demand. This review summarizes recent emerging advances on the contribution of mTORC2 and its associated signaling on the regulation of glucose metabolism and functional β-cell mass under physiological and pathophysiological conditions in type 2 diabetes.     

Dérivés d'acides 3-(β-d-érythrofuranosyl)-pyrazolecarboxyliques

Treatment of 2,5-anhydro-1-bromo-1-deoxy-2,3-O-isopropylidene-1-p-nitrophenylhydrazono-d-ribose with methyl acetylenecarboxylate gave methyl 3-(2,3-O-isopropylidene-β-d-erythrofuranosyl)-1-p-nitrophenylpyrazole- (8) and 5-carboxylate (9). Amidification at C-5 of 8 was easier than at C-4 of 9. Similarly, dimethyl 3-(2,3-O-isopropylidene-β-d-erythrofuranosyl)- 1 - p-nitrophenylpyrazole-4,5-dicarboxylate gave specifically a 5-carbamoyl derivative, the structure of which was established by comparison of the ¹³C-n.m.r.spectrum with those of a series of glycosylpyrazoles. The correlation between the experimental values of the chemical shifts of the carbon atoms of the pyrazole ring and the values calculated by addition of the contributions of the various groups linked to the ring was better (R 0.98) than the correlations obtained by calculation by the CNDO/2 method of the total electron population (R 0.92) or of the π-electron population of each carbon atom (R 0.85).     

常见绿化树种绦柳(Salix matsudana cv.'Pendula')耗水特性

于2005年5—10月,利用Granier热扩散技术对北京城市绿化树种绦柳液流速率进行连续测定,并同时监测林地光合有效辐射、风速和空气温湿度等气象因子。结果表明：绦柳液流速率具有稳定的昼夜变动规律,日变化曲线呈“宽单峰型”,且晴天比阴天的昼夜差异大;绦柳月平均液流速率从5月开始升高,8月达到最大值,为0.0050 cm·s^-1,随后逐渐下降,10月达到最小值,为0.0013 cm·s^-1;与绦柳液流速率相关性最大的环境因子是光合有效辐射和空气温度,最小的是风速;绦柳每小时的耗水量与边材面积和胸径的相关性大于与树高和树冠投影面积的相关性。     

Coupling of glucose oxidase and Fenton's reaction for a simple and inexpensive assay of β-glucosidase

A simple and inexpensive assay for β-glucosidase, based on the coupling of glucose oxidase and Fenton's reagent has been described. Hydrogen peroxide formed as a result of the action of glucose oxidase on glucose (derived from the action of β-glucosidase on cellobiose) oxidizes ferrous sulphate, resulting in an increase in absorbance. The oxidation products produced a peak of maximum absorbance at 340 nm. Using this assay system, a linear relationship between glucose concentration in the range 5.55–27.78 mmol l^?1(100–500 mg dl^?1) and absorbance was obtained, indicating conformity to Beer's law. The preciseness of the glucose oxidase/Fenton's reagent for the assay of glucose was shown to be satisfactory. β-Glucosidase was assayed using the hexokinase assay reagent and the glucose oxidase/ferrous sulphate reagent. The values obtained using both reagents did not differ significantly. Although 2.6 times less sensitive than the hexokinase reagent when absorbance is measured at 340 nm, the glucose oxidase/Fenton's reagent is 10 times cheaper and could be used satisfactorily for routine assays of β-glucosidase and other carbohydrases including cellulase and amylase. In this respect, fructose, mannose, xylose, sucrose and cellobiose did not affect the sensitivity of the reagent. Of several metals tested, only aluminium interfered with the reagent, decreasing its sensitivity.     

Why don't plants fix nitrogen?

The process of biological nitrogen fixation is restricted to a small number of prokaryotic organisms and the majority of the world's crop plants depend on chemical fertilizers to achieve optimum yields. Need this always be the case or have recent advances in the genetic analysis of nitrogen fixation made the construction of nitrogen-fixing plants a realistic goal?     

Epizootiology of Minchinia costalis in susceptible oysters in Seaside Bays of Virginia's Eastern Shore, 1959–1976

“Seaside Disease” of oysters caused by Minchinia costalis (Haplosporida, Sporozoa) produced annual mortalities on the Seaside of the Delmarva Peninsula along the middle Atlantic Coast from Chesapeake Bay to Delaware Bay, U.S.A. The May–June mortalities occurred from 1959 to 1976 without exception; deaths began in late May, peaked in June, and were usually over by July 1. The pathogen developed rapidly from March to May, and sporulation occurred in connective tissues of all organs in May and June. Exposure to a May–June enzootic was required to obtain infections. The pathogen remained subclinical until late winter of the following year. A sympatric pathogen, Minchinia nelsoni, which kills oysters extensively in lower Chesapeake Bay, was present but caused only minor mortalities. Salinities > 30 parts per thousand seem to favor M. costalis and inhibit M. nelsoni. Prevalences of both diseases in live oysters or gapers are given for 11 of the 18 years monitored.     

利用固定化啤酒酵母合成5'-核苷三磷酸

固定化啤酒酵母细胞由5’-核苷一磷酸(NMPs)合成5’-核苷三磷酸(NTPs)。在250mL摇瓶中加入20g固定化酵母细胞和20mL反应液(NMP 40mmol/L,葡萄糖150mmol/L,K2HPO4-KH2PO4缓冲液250 mmol/L,硫酸镁10mmol/L),pH 7.0,35℃,反应2.5h,NTP转化率达到80%。底物溶液添加NAD 后,该固定化酵母细胞可反复使用10次,NTP的转化率稳定维持在70%以上。     

Safeguarding China′s Botanical HeritageFoundation item: BGCI′S Program in China——BGCI′s integrated conservation programme in China

China′s rich floral diversity includes more than 33000 vascular plant species, representing approximately 10 percent of all known plant species. Over half of these species are endemic to China. However, China′s rapid economic development in the last 30 years and continuous population growth have seriously damaged plant resources in the wild and the ecological environment, resulting in a dramatic increase in the number of endangered species. There are nearly 4000 to 5000 higher plants that are now threatened or on the verge of extinction. To help halt the loss of Chinese plant diversity, Botanic Gardens Conservation International (BGCI) has developed a China programme and opened its first office based in Guangzhou in 2008. This office works along with Chinese partners aiming to secure Chinese plant diversity through integrated conservation approaches with reintroduction/population reinforcement, engagement of local communities in conservation activities, capacity building in horticulture and environmental education and public outreach.     

Vitellogenin’s putative role in <Emphasis Type="Italic">Tegillarca granosa</Emphasis>’s cadmium detoxification

The bloody clam, Tegillarca granosa, is a commercial benthic bivalve, having a strong accumulation ability and torrelence to cadmium. To investigate whether vitellogenin (Vg) is involved in cadmium (Cd) detoxification, the full-length cDNA of T. granosa Vg was cloned, and its expression pattern in response to cadmium exposure was studied compared with the reference metallothionein (MT) gene. The full T. granosa Vg sequence consisted of 8988 bp, including a 6930-bp open reading frame that encoded a 2309 amino acid polypeptide. The deduced Vg protein contained a Vg N-terminal domain, domain of unknown function (DUF1943), SbcC domain, and von Willebrand factor type D domain (VWD). Multiple metal-binding sites were predicted in the deduced T. granosa Vg protein, suggesting its potential in functioning as a metal-binding protein. In addition, Vg expression increased in the T. granosa digestive gland and hemolymph in time-dependent manner after exposure to 1, 3, 6 and 9 μg/L Cd for 28 days. MT expression was measured in parallel with Vg expression, and the latter was more sensitive to Cd induction than the former. Together, results of the present research suggested that Vg may play an important role in T. granosa metal detoxification.     

Un nouvel heteroside nitré extrait d'Annona squamosa

A new glycoside was isolated from a 60% methanol extract of dried leaves and stems of Annona squamosa. Its chemical structure was determined as 4-(-2-nitroethyl)-1-[(6-O-β-d-xylopyranosyl-β-d-glucopyranosyl)oxy] benzene.     

Impact of Women’s Harvest Practices on <Emphasis Type="Italic">Pandanus guillaumetii</Emphasis> in Madagascar’s Lowland Rainforests<Superscript>1</Superscript>

Impact of Women’s Harvest Practices on Pandanus guillaumetii in Madagascar’s Lowland Rainforests. Pandanus guillaumetii B.C. Stone is endemic to the east coast rainforests of Madagascar. The plant is an important non-timber forest product (NTFP) for the local population living near these forests, and its leaves are collected by women to be woven into mats. These mats have economic value and are also used for daily activities. At present, little is known about how local harvesting practices impact this plant species. In this study, we describe women’s local harvest practices and quantify their impact on the P. guillaumetii population. We carried out plant inventories as well as interviews and participatory observations with local people harvesting P. guillaumetii in two villages with different population densities in the Manompana region. Inventories were conducted at varying distances from the villages in order to better understand the influence of human pressure on the plant population. The results suggest that local communities apply practices that tend to minimize the harvest impact on the plant. Harvesting seems to have no effect on the actual density of P. guillaumetii. However, the availability of plants with leaves of sufficient quality for mat production is influenced by human pressure. Considering the decreasing number of plants suitable for handicraft, we assume that their availability in the long term may not fulfill the needs of the local people.