A cDNA clone encoding Brassica calmodulin

A 834 bp cDNA encoding calmodulin (CaM) has been isolated from Brassica juncea. On Northern analysis this cDNA hybridises this cDNA to mRNAs of about 0.9 kb in leaf, silique and peduncle. Genomic Southern analysis indicates the presence of a CaM multigene family in Brassica juncea. Comparison of the predicted amino acid sequence of Brassica CaM with that of Arabidopsis CaM ACaM-2 and ACaM-3 showed 100% homology, which is not unusual, since both plants belong to the family Cruciferae. In situ hybridisation studies on Brassica seedlings using a digoxigenin-labelled RNA probe showed that high levels of CaM mRNA were detected in the leaf primordia and the shoot apical meristem, and to a lesser degree, in the zone of root elongation of the root tip. The occurrence of a higher rate of cell division and growth in these regions than its surrounding tissue may possibly be related to higher levels of CaM mRNA.     

肌肽对绵羊精子无氧酵解的影响

在无氧条件下,绵羊精子通过酵解途径获得能量,代谢结果产生大量乳酸,本实验通过测定精子悬液中果糖摄取以及乳酸生成量,研究肌肽、棉酚对绵羊精子酵解途径的影响,结果表明：４ｍＭ肌肽对绵羊精子酵解有显著增强作用,并能刺激精子对果糖的摄取。１２μＭ棉酚对绵羊精子无明显抑制,棉酚能部分抑制肌肽对精子的酵解作用。     

Limitations to net photosynthesis as affected by nitrogen status in jack pine (Pinus banksiana Lamb.) seedlings

Relative limitations of nitrogen (N) status on the processescontributing to photosynthetic rate (A) were investigated. Jackpine {Pinus banksiana Lamb.) seedlings from seeds grown in sandculture were supplied with four different N treatments for 6weeks, which resulted in a needle N content ranging from 50–85mmol m^–2 (14–32 mg g^–1 dry weight). Leaf gasexchange at varying CO₂ levels was measured and limitationson A₃₅₀ (A at ambient CO₂ level) caused by finite, limitingcarboxylation efficiency (c.e.), maximum A (A_max)and stomatalconductance were estimated from an analysis of the responseof A to internal CO₂ concentration. Although c.e. and A_max decreasedlinearly with the decline in needle N, the magnitudes of theirchanges relative to A₃₅₀ differed. A_max varied with A₃₅₀ andalways exceeded A₃₅₀ by 37–38% c.e., however, declinedfaster than A₃₅₀, as needle N level decreased. Consequently,relative limitation on A₃₅₀ caused by inefficient A_max remainedconstant, but limitations caused by c.e. increased by 10–15%at low N levels. In contrast, the limitation by stomatal conductancedeclined initially, but remained stable when N content droppedbelow 75 mmol m^–2. The results suggest: (1) a decreasein biochemical capacity, but not stomatal conductance, contributedto the reduction of A₃₅₀ induced by N-deficiency in jack pineseedlings; and (2) the capacity of carboxylation appeared tobe impaired more than that of electron transport and/or photophosphorylationand its reduction may be the major reason for the reductionin A₃₅₀. Key words: A–C_i analysis, carboxylation efficiency, electron transport, nitrogen deficiency, stomatal conductance     

Genomic fingerprints of Salmonella species generated with repetitive element sequence-based PCR

We describe the use of repetitive element sequence-based PCR (rep-PCR) on the two repetitive sequences, REP and ERIC elements, to distinguish members of closely related Salmonella species. Within the species, ERIC–PCR showed a higher discriminative potential than REP–PCR, but by using a combination of the two PCR methods it was possible to distinguish all the isolates examined. The rep-PCR fingerprints of Salmonella organisms were distinctly different from some Gram-positive bacteria, for example Staphylococcus, Bacillus megaterium, and even the closely related Escherichia coli and Serratia marcescens. Identical fingerprints were observed with whole-cell preparations. Rapid specimen preparation has enhanced the value of rep-PCR in timely analysis of epidemiological relationships.     

Molecular modeling studies on the ribosome

In the absence of a high resolution crystal structure for the ribosome, numerous research groups are carrying out low resolution structural studies using neutron diffraction, electron microscopy, fluorescence energy transfer, chemical crosslinking, chemical footprinting studies, and other methods. We have developed a computer-based refinement method for incorporating these data into low resolution three-dimensional models. The method is based on a molecular mechanics approach, with proteins represented by spherical particles of suitable diameter and the ribosomal RNA represented by a string of spherical pseudoatoms, one for each nucleotide. Experimental data are used to derive constraints that are introduced through a special force field (potential function). Models are refined by simulated annealing. Since every term in the force field is quadratic, any model that satisfies all of the input data has an energy of zero; higher energies indicate residual unsatisfied constraints. The residual energy provides a quantitative statement of model quality and can be used to identify conflicts in the experimental data. The method has been applied to the refinement of a low resolution model for the 30S subunit (the small subunit) of theE. coli ribosome. Since this is a very underdetermined system, the range of acceptable models has also been explored. This provides an estimate of the resolution of the structure, which is about 15 Å overall, with the uncertainty in position of individual nucleotides ranging from about 5 Å to 50 Å.     

河南新乡地区儿童头面部测量

本文对河南省新乡地区汉族儿童（４－１３岁）头面部进行了测量,比较和分析了儿童体质发育与年龄增长的关系,据儿童头面部各指数数值大小分型,确定该地区汉族儿童面部的形态为：圆头型、高头型、狭头型、狭面型、狭鼻型。     

催产素在脊髓水平对电针镇痛的影响

采用玻璃微电极胞外记录和脊髓表面给药的方法观察了催产素（ＯＴ）、抗催产素血清（ＡＯＴＳ）以及电针穴位对背角神经元伤害性诱发放电的影响。结果表明：电针穴位或脊髓表面施加ＯＴ可部分抑制脊髓背角神经元的伤害性诱发放电;在电针的基础上施加ＯＴ则明显加强电针的抑制效应;相反,用ＡＯＴＳ预处理后,电针的抑制作用放取消。提示ＯＴ在脊髓水平参与了对痛觉信息的调制,并与一定频率的针刺镇痛有关。     

Effect of culture conditions on batch growth of Saccharomycopsis lipolytica on olive oil

Summary Batch cultures of Saccharomycopsis lipolytica were grown in minimal medium with olive oil as carbon source. Inocula of glucose-grown cells commenced growth with little lag at rates largely unaffected by variations in the stirring rate or oil concentration. However, growth rates declined when the medium pH was below 7.0. In all cultures, media pH declined with increasing cell concentration. Cell composition during exponential growth was 42% protein and 2% fat. Carbon-limited cells maintained this composition after oil exhaustion but during nitrogen- and oxygen-limited growth, protein content decreased and fat content increased although the protein decrease was only transient with oxygen limitation. Yield coefficients for triglyceride were near unity for all cultures. Free acid concentrations rose rapidly after inoculation. As fermentations progressed, free glycerol appeared and concentrations of di- and monoglycerides passed through maximal values although peak concentrations of di- and monoglycerides persisted for extended times in oxygen- and nitrogen-limited cultures respectively. The fraction of free glycerol consumed was greater in oxygen-limited than in carbon- or nitrogen-limited culture. The basic requirements for growth of yeasts on fatty wastes are discussed with reference to these observations.     

Exfoliative cytology in the evaluation of interferon treatment of cervical intraepithelial neoplasia

Local interferon injection in four patients with cervical intraepithelial neoplasia (CIN) regularly elicited progressive regression of the lesions. The response was observed with exfoliative cytology after each injection, guided by colposcopic examination. The cytologic changes showed a cytocidal effect mainly on the dyskaryotic cells, preceded by cellular degeneration not unlike that of nonspecific inflammation and accompanied by an increase in neutrophil infiltration. The cytologic response was closely correlated with partial or complete clinical regression based on the absence of viable or degenerated dyskaryotic cells in the cervical smears. Three patients showed complete clinical regression after treatment. One patient showed recurrent viable dyskaryotic cells when the dosage was reduced, and treatment was suspended temporarily although her lesion had regressed completely after five injections. Clinical recurrence was noted one week after viable dyskaryotic cells reappeared in her smears. These observations suggest that cytology may be a useful means of monitoring interferon treatment in CIN.