粘虫的发育和成活与环境湿度的关系——Ⅰ.卵和一龄幼虫

在25℃中,相对湿度为20—100%的范围内,卵的孵化率受湿度的影响不明显,在32℃中,相对湿度为40-100%的范围内,湿度对卵孵化率的影响亦不显著,但当相对湿度降至20%时,孵化率即有明显的下降;在25℃及32℃中,相对湿度对卵的发育速度有明显的影响,随相对湿度的增加,发育加快,二者呈直线正相关。 卵期湿度对一龄幼虫的成活及发育有明显的影响,在32℃中,随着卵期湿度的增加,幼虫成活率提高,二者呈正相关;在25℃及60%以下的相对湿度中,亦获得了相似的结果;25℃及32℃中,一龄幼虫的发育速率与卵期相对湿度呈正相关,随卵期湿度的增加,发育加快。 一龄幼虫期的湿度条件,对一龄幼虫有明显的影响,在25℃中,幼虫的成活率和发育速率与相对湿度均呈正相关,在32℃中,这种影响更为显著,当湿度降低到40%时,全部幼虫均不能存活,在60%以上的相对湿度中,成活率和发育速率均随湿度的提高而增加。     

望谟县蚊类初步调查报告

望谟县位于我省的最南部,在北纬25°—25°30′,东经106°—106°20′区内,南面隔红水河与广西呲隣。1958年3—5月间我们在该县南端的蔗乐板、陈乐康等乡迸行疟疾流行病学调查的同寸,对当地蚊虫孳生与栖息场所进行了全面的普查。据蔗乐水文站记录:当地海拔为400米左右,1953—1957年的年平均温度为20.16℃,月平均温度最低为11.52℃(1月),最高为27.08℃(7     

Microalbuminuria as predictor of increased mortality in elderly people.

OBJECTIVE--Correlation of the urinary albumin excretion rate and the risk of death among elderly subjects. DESIGN--216 Subjects aged 60-74 whose urinary albumin excretion rate had been determined were followed up 62-83 months later. SETTING--Municipality of Fredericia, Denmark. SUBJECTS--223 People who had been selected as control subjects for diabetics found during a systematic screening for diabetes of all people aged 60-74 living in the municipality of Fredericia, Denmark. Of these subjects, 216 had an extensive clinical and biochemical examination within a few weeks of selection. MAIN OUTCOME MEASURE--Death. RESULTS--The median urinary albumin excretion rate was 7.52 micrograms/min. Eight of those with a rate below the median died compared with 23 with a rate equal to or greater than the median (p = 0.0078). The median albumin excretion rate in the 31 who died was 15.00 micrograms/min. Cardiovascular disease was the most common cause of death in both groups. A multivariate regression analysis of survival data was performed using the proportional hazards model. Besides albumin excretion rate, male sex, serum creatinine concentration, and hypertension were found to be of prognostic value. CONCLUSIONS--The association between the albumin excretion rate and mortality that has been described in recent years in patients with diabetes mellitus may be present in elderly people in general, even when other known risk factors are taken into account.     

Microtubule polarities indicate that nucleation and capture of microtubules occurs at cell surfaces in Drosophila

Hook decoration with pig brain tubulin was used to assess the polarity of microtubules which mainly have 15 protofilaments in the transcellular bundles of late pupal Drosophila wing epidermal cells. The microtubules make end-on contact with cell surfaces. Most microtubules in each bundle exhibited a uniform polarity. They were oriented with their minus ends associated with their hemidesmosomal anchorage points at the apical cuticle-secreting surfaces of the cells. Plus ends were directed towards, and were sometimes connected to, basal attachment desmosomes at the opposite ends of the cells. The orientation of microtubules at cell apices, with minus ends directed towards the cell surface, is opposite to the polarity anticipated for microtubules which have elongated centrifugally from centrosomes. It is consistent, however, with evidence that microtubule assembly is nucleated by plasma membrane-associated sites at the apical surfaces of the cells (Mogensen, M. M., and J. B. Tucker. 1987. J. Cell Sci. 88:95-107) after these cells have lost their centriole-containing, centrosomal, microtubule-organizing centers (Tucker, J. B., M. J. Milner, D. A. Currie, J. W. Muir, D. A. Forrest, and M.-J. Spencer. 1986. Eur. J. Cell Biol. 41:279-289). Our findings indicate that the plus ends of many of these apically nucleated microtubules are captured by the basal desmosomes. Hence, the situation may be analogous to the polar-nucleation/chromosomal-capture scheme for kinetochore microtubule assembly in mitotic and meiotic spindles. The cell surface-associated nucleation-elongation-capture mechanism proposed here may also apply during assembly of transcellular microtubule arrays in certain other animal tissue cell types.     

Water Relations and Cell Wall Elasticity Quantities in Phaseolus vulgaris Leaves

The investigations were designed to test osmotic adjustment,cell wall bulk elastic modulus and stomatal behaviour duringand after water stress and rewatering in the primary and firsttrifoliolate leaf of Phaseolus vulgaris. Leaf water relationsquantities fully recovered after rewatering within a few hours;diffusion resistance to vapour flow, however, required 6 h.Leaf growth recovery was considerably delayed. Osmotic adjustmentwas absent during water stress in both the primary and the firsttrifoliolate leaf. The bulk elastic modulus (_v), however, waslower for the primary leaf (higher elasticity) than for thetrifoliolate leaves. These two types of leaves differed in theirdrought resistance in that the primary leaf exhibited wiltingat the end of the stress period (7 d) while the trifoliolateleaf remained relatively turgid. The bulk elastic modulus ofthe cell wall changed almost proportionally with the turgorpressure (_p). The structure coefficient (), an indicator forthe intensity of change of the bulk elastic modulus with turgorwas higher for the primary than for the first trifoliolate leaf.The leaf diffusion resistance (r), below the turgor loss point,changed proportionally with the solute potential with very similarregression lines for the relation of (r) versus RWC ¹. The datasuggest that greater drought resistance of the first trifoliolateleaf is related to a decreased bulk elastic modulus, but notto osmotic adjustment nor to differences in stomatal resistanceduring water stress. Key words: Phaseolus vulguris, Water stress, Recovery, Cell wall elasticity     

Soluble invertase expression is an early target of drought stress during the critical,abortion-sensitive phase of young ovary development in maize

To distinguish their roles in early kernel development and stress, expression of soluble (Ivr2) and insoluble (Incw2) acid invertases was analyzed in young ovaries of maize (Zea mays) from 6 d before (-6 d) to 7 d after pollination (+7 d) and in response to perturbation by drought stress treatments. The Ivr2 soluble invertase mRNA was more abundant than the Incw2 mRNA throughout pre- and early post-pollination development (peaking at +3 d). In contrast, Incw2 mRNAs increased only after pollination. Drought repression of the Ivr2 soluble invertase also preceded changes in Incw2, with soluble activity responding before pollination (-4 d). Distinct profiles of Ivr2 and Incw2 mRNAs correlated with respective enzyme activities and indicated separate roles for these invertases during ovary development and stress. In addition, the drought-induced decrease and developmental changes of ovary hexose to sucrose ratio correlated with activity of soluble but not insoluble invertase. Ovary abscisic acid levels were increased by severe drought only at -6 d and did not appear to directly affect Ivr2 expression. In situ analysis showed localized activity and Ivr2 mRNA for soluble invertase at sites of phloem-unloading and expanding maternal tissues (greatest in terminal vascular zones and nearby cells of pericarp, pedicel, and basal nucellus). This early pattern of maternal invertase localization is clearly distinct from the well-characterized association of insoluble invertase with the basal endosperm later in development. This localization, the shifts in endogenous hexose to sucrose environment, and the distinct timing of soluble and insoluble invertase expression during development and stress collectively indicate a key role and critical sensitivity of the Ivr2 soluble invertase gene during the early, abortion-susceptible phase of development.