4种红景天植物的组织培养研究

以大花红景天、云南红景天、长鞭红景天和库页红景天的茎和叶为外植体进行组织培养,结果表明：大花红景天以茎为外植体诱导芽效果最好,其它3种红景天以叶为外植体诱导芽效果最好。云南红景天和长鞭红景天适合的芽诱导激素组合是0．1mg／L NAA和2．5mg／L 6-BA的组合,在该激素水平下两种红景天的出芽频率分别达到71％和84％;大花红景天和库叶红景天适合的芽诱导激素组合是0．5mg／L NAA和2．5mg／L 6-BA的组合,在该激素水平下两种红景天的出芽频率均达到80％。长鞭红景天和库叶红景天在添加IBA的培养基上容易生根形成完整植株,生根率分别达到87％和73％;经过炼苗后,长鞭红景天再生苗能够成功移栽,成活率达66％。     

Structural Determinants and Proliferative Consequences of Connexin 37 Hemichannel Function in Insulinoma Cells

Connexin (Cx) 37 suppresses vascular and cancer cell proliferation. The C terminus and a channel able to function are necessary, and neither by itself is sufficient, for Cx37 to mediate growth suppression. Cx37 supports transmembrane and intercellular signaling by forming functional hemichannels (HCs) and gap junction channels (GJCs), respectively. Here we determined whether Cx37 with HC, but not GJC, functionality would suppress proliferation of rat insulinoma (Rin) cells comparably to wild-type Cx37 (Cx37-WT). We mutated extracellular loop residues hypothesized to compromise HC docking but not HC function (six cysteines mutated to alanine, C54A,C61A,C65A, C187A,C192A,C198A (designated as C₆A); N55I; and Q58L). All three mutants trafficked to the plasma membrane and formed protein plaques comparably to Cx37-WT. None of the mutants formed functional GJCs, and Cx37-C₆A did not form functional HCs. Cx37-N55I and -Q58L formed HCs with behavior and permeation properties similar to Cx37-WT (especially Q58L), but none of the mutants suppressed Rin cell proliferation. The data indicate that determinants of Cx37 HC function differ from other Cxs and that HC functions with associated HC-supported protein-protein interactions are not sufficient for Cx37 to suppress Rin cell proliferation. Together with previously published data, these results suggest that Cx37 suppresses Rin cell proliferation only when in a specific conformation achieved by interaction of the C terminus with a Cx37 pore-forming domain able to open as a GJC.     

Moms at Work and Dads at Home: Children's Evaluations of Parental Roles

Children's evaluations of two parental roles, working outside the home, and staying home to take care of children, were assessed in second (M = 7.13 years, SD = .39) and fifth grade (M = 10.42, SD = .57) students (N = 121). Children viewed it as acceptable for both mothers and fathers to work full-time, and used personal choice and social conventional reasons as justifications. In contrast, children found it less acceptable for fathers to stay at home than for mothers to stay at home, and they used gender stereotypes about domestic roles as justifications. With age, children were more flexible in their reasoning and used fewer stereotypes in their evaluations; children from traditional family structures used more stereotypic expectations than did children from non-traditional ones. Overall, children's interpretations of competence in a caretaker role was highly contingent on the gender of the parent.     

Work Characteristics and Personal Social Support as Determinants of Subjective Well-Being

Background

Well-being is an important health outcome and a potential national indicator of policy success. There is a need for longitudinal epidemiological surveys to understand determinants of well-being. This study examines the role of personal social support and psychosocial work environment as predictors of well-being in an occupational cohort study.

Methods

Social support and work characteristics were measured by questionnaire in 5182 United Kingdom civil servants from phase 1 of the Whitehall II study and were used to predict subjective well-being assessed using the Affect Balance Scale (range -15 to 15, SD = 4.2) at phase 2. External assessments of job control and demands were provided by personnel managers.

Results

Higher levels of well-being were predicted by high levels of confiding/emotional support (difference in mean from the reference group with low levels of confiding/emotional support  =  0.63, 95%CI 0.38–0.89, p_trend<0.001), high control at work (0.57, 95%CI 0.31–0.83, p_trend<0.001; reference low control) and low levels of job strain (0.60, 95%CI 0.31–0.88; reference high job strain), after adjusting for a range of confounding factors and affect balance score at baseline. Higher externally assessed work pace was also associated with greater well-being.

Conclusions

Our results suggest that the psychosocial work environment and personal relationships have independent effects on subjective well-being. Policies designed to increase national well-being should take account of the quality of working conditions and factors that facilitate positive personal relationships. Policies designed to improve workplaces should focus not only on minimising negative aspects of work but also on increasing the positive aspects of work.     

Interaction of Fibroblast Growth Factor-2 (FGF-2) with Free Gangliosides: Biochemical Characterization and Biological Consequences in Endothelial Cell Cultures

Exogenous gangliosides affect the angiogenic activity of fibroblast growth factor-2 (FGF-2), but their mechanism of action has not been elucidated. Here, a possible direct interaction of sialo-glycolipids with FGF-2 has been investigated. Size exclusion chromatography demonstrates that native, but not heat-denatured, ¹²⁵I-FGF-2 binds to micelles formed by gangliosides GT_1b, GD_1b, or GM₁. Also, gangliosides protect native FGF-2 from trypsin digestion at micromolar concentrations, the order of relative potency being GT_1b > GD_1b > GM₁ = GM₂ = sulfatide > GM₃ = galactosyl-ceramide, whereas asialo-GM₁, neuraminic acid, and N-acetylneuramin-lactose were ineffective. Scatchard plot analysis of the binding data of fluorochrome-labeled GM₁ to immobilized FGF-2 indicates that FGF–2/GM₁ interaction occurs with a K_d equal to 6 μM. This interaction is inhibited by the sialic acid-binding peptide mastoparan and by the synthetic fragments FGF-2(112–129) and, to a lesser extent, FGF-2(130–155), whereas peptides FGF-2(10–33), FGF-2(39–59), FGF-2(86–96), and the basic peptide HIV-1 Tat(41–60) were ineffective. These data identify the COOH terminus of FGF-2 as a putative ganglioside-binding region. Exogenous gangliosides inhibit the binding of ¹²⁵I-FGF-2 to high-affinity tyrosine-kinase FGF-receptors (FGFRs) of endothelial GM 7373 cells at micromolar concentrations. The order of relative potency was GT_1b > GD_1b > GM₁ > sulfatide a = sialo-GM₁. Accordingly, GT_1b,GD_1b, GM₁, and GM₂, but not GM₃ and asialo-GM₁, prevent the binding of ¹²⁵I-FGF-2 to a soluble, recombinant form of extracellular FGFR-1. Conversely, the soluble receptor and free heparin inhibit the interaction of fluorochrome-labeled GM₁ to immobilized FGF-2. In agreement with their FGFR antagonist activity, free gangliosides inhibit the mitogenic activity exerted by FGF-2 on endothelial cells in the same range of concentrations. Also in this case, GT_1b was the most effective among the gangliosides tested while asialo-GM₁, neuraminic acid, N-acetylneuramin-lactose, galactosyl-ceramide, and sulfatide were ineffective. In conclusion, the data demonstrate the capacity of exogenous gangliosides to interact with FGF-2. This interaction involves the COOH terminus of the FGF-2 molecule and depends on the structure of the oligosaccharide chain and on the presence of sialic acid residue(s) in the ganglioside molecule. Exogenous gangliosides act as FGF-2 antagonists when added to endothelial cell cultures. Since gangliosides are extensively shed by tumor cells and reach elevated levels in the serum of tumor-bearing patients, our data suggest that exogenous gangliosides may affect endothelial cell function by a direct interaction with FGF-2, thus modulating tumor neovascularization.     

On NCATE Standards and Culture at Work: Conversations, Hegemony, and (Dis-)Abling Consequences

Many are unaware of the power of the NCATE standards for the accreditation of schools of education. In this article, I first trace the development of the political authority of these standards, and their imposition on hundreds of schools of education. I then focus on the discourse of these standards, particularly the emphasis on "knowledge, skills and dispositions" as personal properties to control. I conclude with a call to highlight the struggles in which all involved are engaged.     

Determinants and Consequences of Failure of Linkage to Antiretroviral Therapy at Primary Care Level in Blantyre, Malawi: A Prospective Cohort Study

Background

Poor rates of linkage from HIV diagnosis to ART initiation are a major barrier to universal coverage of ART in sub-Saharan Africa, with reasons for failure poorly understood. In the first study of this kind at primary care level, we investigated the pathway to care in the Malawian National Programme, one of the strongest in Africa.

Methods and Findings

A prospective cohort study was undertaken at two primary care clinics in Blantyre, Malawi. Newly diagnosed HIV-positive adults (>15 years) were followed for 6-months to assess completion of eligibility assessments, initiation of ART and death. Two hundred and eighty participants were followed for 82.6 patient-years. ART eligibility assessments were problematic: only 134 (47.9%) received same day WHO staging and 121 (53.2%) completed assessments by 6-months. Completion of CD4 measurement (stage 1/2 only) was 81/153 (52.9%). By 6-months, 87/280 (31.1%) had initiated ART with higher uptake in participants who were ART eligible (68/91, 74.7%), and among participants who received same-day staging (52/134 [38.8%] vs. 35/146 [24.0%] p = 0.007). Non-completion of ART eligibility assessments (adjusted hazard ratio: 0.11, 95% CI: 0.06–0.21) was associated with failure to initiate ART. Retention in pre-ART care for non-ART initiators was low (55/193 [28.5%]). Of the 15 (5.4%) deaths, 11 (73.3%) occurred after ART initiation.

Conclusions

Although uptake of ART was high and prompt for patients with known eligibility, there was frequent failure to complete eligibility assessment and poor retention in pre-ART care. HIV care programmes should urgently evaluate the way patients are linked to ART. In particular, there is a critical need for simplified, same-day ART eligibility assessments, reduced requirements for hospital visits, and active defaulter follow-up.     

Phytoremediation Efficiency of a PCP-Contaminated Soil using Four Plant Species as Mono- and Mixed Cultures

Bioremediation of soil polluted by pentachlorophenol (PCP) is of great importance due to the persistence and carcinogenic properties of PCP. Phytoremediation has long been recognized as a promising approach for removal of PCP from soil. The present study was conducted to investigate the capability of four plant species; white clover, ryegrass, alfalfa, and rapeseed grown alone and in combination to remediate pentachlorophenol contaminated soil. After 60 days cultivation, white clover, raygrass, alfalfa, and rapeseed all significantly enhanced the degradation of PCP in soils. Alfalfa showed highest efficiency for the removal of PCP in single cropping flowed by rapeseed and ryegrass. Mixed cropping significantly enhanced the remediation efficiencies as compared to single cropping; about 89.84% of PCP was removed by mixed cropping of rapeseed and alfalfa, and 72.01% of PCP by mixed cropping of rape and white clover. Mixed cropping of rapeseed with alfalfa was however far better for the remediation of soil PCP than single cropping. An evaluation of soil biological activities as a monitoring mechanism for the bioremediation process of a PCP-contaminated soil was made using measurements of microbial counts and dehydrogenase activity.     

Carbonyl Stress in Bacteria: Causes and Consequences

Pathways of synthesis of the α-reactive carbonyl compound methylglyoxal (MG) in prokaryotes are described in this review. Accumulation of MG leads to development of carbonyl stress. Some pathways of MG formation are similar for both pro- and eukaryotes, but there are reactions specific for prokaryotes, e.g. the methylglyoxal synthase reaction. This reaction and the glyoxalase system constitute an alternative pathway of glucose catabolism–the MG shunt not associated with the synthesis of ATP. In violation of the regulation of metabolism, the cell uses MG shunt as well as other glycolysis shunting pathways and futile cycles enabling stabilization of its energetic status. MG was first examined as a biologically active metabolic factor participating in the formation of phenotypic polymorphism and hyperpersistent potential of bacterial populations. The study of carbonyl stress is interesting for evolutionary biology and can be useful for constructing highly effective producer strains.     

Growth Rate-Dependent Modulation of Carbon Flux through Central Metabolism and the Kinetic Consequences for Glucose-Limited Chemostat Cultures of Corynebacterium glutamicum

The physiological behavior of Corynebacterium glutamicum in glucose-limited chemostat cultures was examined from both growth kinetics and enzymatic viewpoints. Metabolic fluxes within the central metabolism were calculated from growth kinetics and analyzed in relation to specific enzyme activities. At high growth rates, incomplete glucose removal was observed, and this was attributed to rate-limiting capacity of the phosphotransferase system transporter and the probable contribution of a low-affinity permease uptake mechanism. The improved biomass yield observed at high growth rates was related to a shift in the profile of anaplerotic carboxylation reactions, with pyruvate carboxylase replacing malic enzyme. Phosphoenolpyruvate carboxylase, an activity often assumed to be the major anaplerotic reaction during growth of C. glutamicum on glucose, was present at only low levels and is unlikely to contribute significantly to tricarboxylic acid cycle fuelling other than at low growth rates.     

Hair: Its Power and Meaning in Asian Cultures

Hair: Its Power and Meaning in Asian Cultures. Alf Hiltebeitel and Barbara D. Miller. eds. Albany: State University of New York Press, 1998. 298 pp.