福建省不同居群轮叶蒲桃叶形态与表皮特征比较

通过对福建省16个不同居群轮叶蒲桃叶片形态特征、叶表皮特征的观察及叶片主要性状的测量,探讨不同居群轮叶蒲桃叶型、叶表皮特征多样性,为属下种间鉴定提供依据。对16个居群轮叶蒲桃叶型多样性进行观察,采用直尺测量叶片主要性状如叶长、叶宽等;采用光学显微镜和扫描电镜对叶表皮特征进行观察。结果表明,16个居群轮叶蒲桃叶片中,闽西居群叶形为阔椭圆形;闽东、闽北、闽南等各地居群叶形为长椭圆形或近带形。不同居群轮叶蒲桃叶片表皮毛、角质层纹饰、气孔器形态与类型等表现一致,但表皮细胞垂周壁式样差异明显,具波状、浅波状、平直、弓形等几种类型,且在上下表皮间存在式样一致或有多元化现象。由此说明,福建省不同居群轮叶蒲桃叶形与表皮细胞垂周壁式样均处于较强烈分化的状态,表皮细胞垂周壁式样不能作为属种间分类的依据。     

Acyl coenzyme A dependent retinol esterification by acyl coenzyme A: diacylglycerol acyltransferase 1

We provide biochemical evidence that enzymes involved in the synthesis of triacylglycerol, namely acyl coenzyme A:diacylglycerol acyltransferase (DGAT) and acyl coenzyme A:monoacylglycerol acyltransferase (MGAT), are capable of carrying out the acyl coenzyme A:retinol acyltransferase (ARAT) reaction. Among them, DGAT1 appears to have the highest specific activity. The apparent K(m) values of recombinant DGAT1/ARAT for retinol and palmitoyl coenzyme A were determined to be 25.9+/-2.1 microM and 13.9+/-0.3 microM, respectively, both of which are similar to the values previously determined for ARAT in native tissues. A novel selective DGAT1 inhibitor, XP620, inhibits recombinant DGAT1/ARAT at the retinol recognition site. In the differentiated Caco-2 cell membranes, XP620 inhibits approximately 85% of the Caco-2/ARAT activity indicating that DGAT1/ARAT may be the major source of ARAT activity in these cells. Of the two most abundant fatty acyl retinyl esters present in the intact differentiated Caco-2 cells, XP620 selectively inhibits retinyl-oleate formation without influencing the retinyl-palmitate formation. Using this inhibitor, we estimate that approximately 64% of total retinyl ester formation occurs via DGAT1/ARAT. These studies suggest that DGAT1/ARAT is the major enzyme involved in retinyl ester synthesis in Caco-2 cells.     

Sensitivity of striate neurons to Y-like figures: experiment and simulation

Under stimulation of the receptive fields (RF) of neurons in the cat area 17 by flashing Y-like figures of different shape and orientation, the sensitivity to these figures was revealed in 72% of the studied cells, while 62% of units were sensitive to cross-like figures as well. Tuning to Y-like figures was typically selective to their shape and orientation, but in some cases it was invariant to these features. Response magnitudes to single bar, Y-like figure and cross were positively correlated. Simulation showed that the disinhibition might be a sufficient mechanism for effective detection of Y-like figures in a classical receptive field.     

Comparison between morphometry and immunostaining of malignant cells in non-small cell lung cancer

OBJECTIVE: To investigate the morphometric properties of tumor cells in combination with the expression of 5 immunomarkers, quantitatively evaluated by image analysis, in a series of 60 non-small cell lung carcinomas (NSCLCs) and to assess their prognostic significance. STUDY DESIGN: Tissue sections from 60 NSCLCs were assessed for the expression of p53, Ki-67, bcl-2, bax and FasL using immunohistochemistry and antibodies. Correlations between morphometric features and clinicopathologic variables, including overall survival and the expression of the above markers, were statistically investigated. RESULTS: Major and minor axis nuclear values, as well as nuclear area and perimeter values, were positively interrelated. No statistically significant correlations were observed between nuclear morphometry and any of the clinicopathologic parameters. p53 Accumulation, when quantitatively estimated, displayed a positive correlation with major axis (P = .008), minor axis (P = .06), nuclear perimeter (P = .006) and mainly nuclear area values (P = .003). Bcl-2- and bax-quantified immunostaining demonstrated a weak negative correlation with shape factor values (P = .039 and P = .025, respectively). Univariate and multivariate analysis showed that stage was the only significant predictor of survival in all patients. In univariate statistical analysis there was a trend between worse survival and shape factor values < 0.8 (P = .0791); this trend almost reached statistical significance in the subgroup of squamous cell carcinomas (P = .0570). CONCLUSION: p53 Accumulation, when quantified, appears to be positively linked with nuclear morphometric values. The prognostic significance of shape factor in NSCLC warrants further investigation.     

Retinol esterification in Sertoli cells by lecithin-retinol acyltransferase

Esterification of retinol occurs during the metabolism of vitamin A in the testis. An acyl-CoA:retinol acyltransferase (ARAT) activity has been described for microsomes isolated from testis homogenates. That activity was also observed here in microsomal preparations obtained from cultured Sertoli cells from 20-day-old (midpubertal) rats. ARAT catalyzed the synthesis of retinyl laurate when free retinol and lauroyl-CoA were provided as substrates. However, in the absence of exogenous acyl-CoA, retinol was esterified by a different activity in a manner similar to the lecithin:retinol acyltransferase (LRAT) activity described recently for liver and intestine. Microsomal preparations obtained from enriched Sertoli cell fractions from the adult rat testis had 75-fold higher levels of LRAT than the preparations from midpubertal animals, but ARAT activity was the same in both these preparations. LRAT utilized an endogenous acyl donor and either unbound retinol or retinol complexed with cellular retinol-binding protein (CRBP) to catalyze the synthesis of retinyl linoleate, retinyl oleate, retinyl palmitate, and retinyl stearate. The addition of exogenous dilaurylphosphatidylcholine (DLPC) resulted in the synthesis of retinyl laurate. The esterification from both exogenous DLPC and endogenous acyl donor was inhibited by 2 mM phenylmethanesulfonyl fluoride (PMSF). ARAT activity was not affected by similar concentrations of PMSF. Furthermore, retinol bound to CRBP, a protein known to be present in Sertoli cells, was not an effective substrate for testicular ARAT. When retinol uptake and metabolism were examined in cultured Sertoli cells from 20-day-old rats, the cells synthesized the same retinyl esters that were produced by microsomal LRAT in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)     

Acyl coenzyme A dependent retinol esterification by acyl coenzyme A:diacylglycerol acyltransferase 1

We provide biochemical evidence that enzymes involved in the synthesis of triacylglycerol, namely acyl coenzyme A:diacylglycerol acyltransferase (DGAT) and acyl coenzyme A:monoacylglycerol acyltransferase (MGAT), are capable of carrying out the acyl coenzyme A:retinol acyltransferase (ARAT) reaction. Among them, DGAT1 appears to have the highest specific activity. The apparent K_m values of recombinant DGAT1/ARAT for retinol and palmitoyl coenzyme A were determined to be 25.9 ± 2.1 μM and 13.9 ± 0.3 μM, respectively, both of which are similar to the values previously determined for ARAT in native tissues. A novel selective DGAT1 inhibitor, XP620, inhibits recombinant DGAT1/ARAT at the retinol recognition site. In the differentiated Caco-2 cell membranes, XP620 inhibits ～85% of the Caco-2/ARAT activity indicating that DGAT1/ARAT may be the major source of ARAT activity in these cells. Of the two most abundant fatty acyl retinyl esters present in the intact differentiated Caco-2 cells, XP620 selectively inhibits retinyl–oleate formation without influencing the retinyl–palmitate formation. Using this inhibitor, we estimate that ～64% of total retinyl ester formation occurs via DGAT1/ARAT. These studies suggest that DGAT1/ARAT is the major enzyme involved in retinyl ester synthesis in Caco-2 cells.     

Realized Sampling Variances of Estimates of Genetic Parameters and the Difference between Genetic and Phenotypic Correlations

A data set of 1572 heritability estimates and 1015 pairs of genetic and phenotypic correlation estimates, constructed from a survey of published beef cattle genetic parameter estimates, provided a rare opportunity to study realized sampling variances of genetic parameter estimates. The distribution of both heritability estimates and genetic correlation estimates, when plotted against estimated accuracy, was consistent with random error variance being some three times the sampling variance predicted from standard formulae. This result was consistent with the observation that the variance of estimates of heritabilities and genetic correlations between populations were about four times the predicted sampling variance, suggesting few real differences in genetic parameters between populations. Except where there was a strong biological or statistical expectation of a difference, there was little evidence for differences between genetic and phenotypic correlations for most trait combinations or for differences in genetic correlations between populations. These results suggest that, even for controlled populations, estimating genetic parameters specific to a given population is less useful than commonly believed. A serendipitous discovery was that, in the standard formula for theoretical standard error of a genetic correlation estimate, the heritabilities refer to the estimated values and not, as seems generally assumed, the true population values.     

Correlated evolution of leaf shape and trichomes in Begonia dregei (Begoniaceae)

Structural features of leaves, including size, shape, and surfaces, vary greatly throughout the plant kingdom. In both functional and phylogenetic analyses of leaves, the various morphological aspects are often considered independently of each other, although it is likely that many combinations of features do not occur at random due to either functional constraint or genetic correlation. The distribution of variation in leaf morphology in the highly variable Begonia dregei species complex was examined in natural populations and in F(2) offspring from a cross between plants from two populations. Leaf shape was quantified using several morphometric measures, and trichomes on leaves were counted and measured. Correlations between leaf shape and the numbers and size of trichomes were examined. There were significant correlations between the shapes of leaves and the presence, number, and size of trichomes among populations and in hybrid plants. Deeply incised leaves had larger numbers of longer trichomes at the sinuses. Higher numbers of trichomes on upper leaf surfaces occurred together with trichomes at the petiole and on the abaxial surface. The potential for independent evolution of leaf shape and trichomes in this group is limited. Hypotheses to explain the correlated development of leaf shape and trichomes are discussed.