水稻小穗轴维管系统网络结构探讨

对籼型、粳型或其不育系与保持系代表品种小穗解剖观察表明：水稻小穗轴维管系统网络由中央维管束和各分枝维管束复合而成。来自小穗柄的１条大的中央主束和几条边围维管束经数次分枝、联结,不断产生新的分枝维管束进入相应的结构。一般颖片中维管束１－２条,第一稃片中１－３条,第二稃片中１－４条,第二朵退化小花残余结构中０－３条,顶生可孕小花的外稃中５条,内稃中３条,浆片中各２条,雄蕊中各１条,雌蕊中３条,主束与支     

Parastrongylus (=Angiostrongylus) cantonensis now endemic in Louisiana wildlife

Parastrongylus (=Angiostrongylus) cantonensis, a lung worm of rats, was first reported in the United States in 1987, with a probable introduction by infected rats from ships docking in New Orleans, Louisiana, during the mid-1980s. Since then, it has been reported in nonhuman primates and a boy from New Orleans, and in a horse from Picayune, Mississippi, a distance of 87 km from New Orleans. Parastrongylus cantonensis infection is herein reported in a lemur (Varencia variegata rubra) from New Iberia, Louisiana, a distance of 222 km from New Orleans, and in a wood rat (Neotomafloridanus) and in 4 opossums (Didelphis virginiana) from Baton Rouge, Louisiana, a distance of 124 km from New Orleans. The potential of a great variety of gastropods serving as intermediate hosts in Louisiana may pose a threat to wildlife as well as to domesticated animals in the areas where infected Norway rats (Rattus norvegicus) are present.     

A model for a network of phosphorylation-dephosphorylation cycles displaying the dynamics of dominoes and clocks

We consider a model for a network of phosphorylation-dephosphorylation cycles coupled through forward and backward regulatory interactions, such that a protein phosphorylated in a given cycle activates the phosphorylation of a protein by a kinase in the next cycle as well as the dephosphorylation of a protein by a phosphatase in a preceding cycle. The network is cyclically organized in such a way that the protein phosphorylated in the last cycle activates the kinase in the first cycle. We study the dynamics of the network in the presence of both forward and backward coupling, in conditions where a threshold exists in each cycle in the amount of protein phosphorylated as a function of the ratio of kinase to phosphatase maximum rates. We show that this system can display sustained (limit-cycle) oscillations in which each cycle in the pathway is successively turned on and off, in a sequence resembling the fall of a series of dominoes. The model thus provides an example of a biochemical system displaying the dynamics of dominoes and clocks (Murray & Kirschner, 1989). It also shows that a continuum of clock waveforms exists of which the fall of dominoes represents a limit. When the cycles in the network are linked through only forward (positive) coupling, bistability is observed, while in the presence of only backward (negative) coupling, the system can display multistability or oscillations, depending on the number of cycles in the network. Inhibition or activation of any kinase or phosphatase in the network immediately stops the oscillations by bringing the system into a stable steady state; oscillations resume when the initial value of the kinase or phosphatase rate is restored. The progression of the system on the limit cycle can thus be temporarily halted as long as an inhibitor is present, much as when a domino is held in place. These results suggest that the eukaryotic cell cycle, governed by a network of phosphorylation-dephosphorylation reactions in which the negative control of cyclin-dependent kinases plays a prominent role, behaves as a limit-cycle oscillator impeded in the presence of inhibitors. We contrast the case where the sequence of domino-like transitions constitutes the clock with the case where the sequence of transitions is passively coupled to a biochemical oscillator operating as an independent clock.     

Molecular cloning and expression of the col2a1a and col2a1b genes in the medaka, Oryzias latipes

The Col2a1 gene is expressed in notochord, otic vesicle, cartilaginous tissue and the anlage of endochondral bone during development in higher vertebrates. Type II collagen, a homotrimeric product of the Col2a1 gene, functions as a key regulatory protein for cartilage development and endochondral ossification. In medaka and zebrafish, a single homolog of the col2a1 gene has been identified. However, it is necessary to note that many genes are duplicated in teleost fishes. To clarify function of col2a1 genes in teleost fishes and to further understand the process of cartilage development and endochondral ossification, we cloned and mapped the gene loci of two col2a1 orthologs in medaka. The proteins encoded by both medaka col2a1a and col2a1b genes were highly conserved (85.3% and 82.6%) relative to human COL2A1, but synteny was not observed. We also examined the expression patterns of col2a1a and col2a1b during embryonic development. Whole-mount insitu hybridization data suggests that expression patterns of both medaka co2a1a and col2a1b genes are similar to that of zebrafish co2a1 in the early embryonic stages. In medaka, the two col2a1 genes show a closely correlated pattern of spatial and temporal expression. In late embryonic stages, however, there were differences in both expression patterns in the pectoral fin. This study is the first report of two homologs of col2a1 in teleosts and also the first examination of col2a1a and col2a1b expression patterns in this group.     

Stimulating role of potassium ions and ouabain on glycogen synthesis in adipose tissue.

1. Exposure of fat-pads to increasing concentrations of K+ in the presence of insulin stimulates the incorporation of labelled glucose into glycogen. In the absence of hormone, only a slight incorporation of glucose into glycogen and slight glucose oxidation were detectable. 2. Ouabain alone, up to 100 microM, had no effect on synthesis of glycogen. Ouabain reinforced the effect of insulin on the conversion of glucose into glycogen in a Na+ medium and in a equimolar Na+-K+ medium, but not in a K+ medium. In addition, ouabain modified the optimal K+/Na+ ratio for glycogen synthesis. 3. The proportion of glycogen synthase in the active form was increased in a K+ medium, and a faster rate of conversion of synthase b into a was observed under these conditions. No difference was detected in the rate of inactivation of phosphorylase in a K+ or a Na+ medium. 4. Even though these results, taken together, are consistent with the proposed role of phosphorylase a in the regulation of synthase activation, the molecular mechanism of action of K+ in adipose tissue in increasing synthesis of glycogen cannot be explained simply by a faster inactivation of phosphorylase a. It is concluded that some undetermined effector(s) or signal could itself be a primary determinant for the greater activation of synthase observed in a K+ medium.     

Characterization and expression pattern of zebrafish Anti-Müllerian hormone (Amh) relative to sox9a, sox9b, and cyp19a1a, during gonad development

The role of Anti-Müllerian hormone (Amh) during gonad development has been studied extensively in mammals, but is less well understood in other vertebrates. In male mammalian embryos, Sox9 activates expression of Amh, which initiates the regression of the Mullerian ducts and inhibits the expression of aromatase (Cyp19a1), the enzyme that converts androgens to estrogens. To better understand shared features of vertebrate gonadogenesis, we cloned amh cDNA from zebrafish, characterized its genomic structure, mapped it, analyzed conserved syntenies, studied its expression pattern in embryos, larvae, juveniles, and adults, and compared it to the expression patterns of sox9a, sox9b and cyp19a1a. We found that the onset of amh expression occurred while gonads were still undifferentiated and sox9a and cyp19a1a were already expressed. In differentiated gonads of juveniles, amh showed a sexually dimorphic expression pattern. In 31 days post-fertilization juveniles, testes expressed amh and sox9a, but not cyp19a1a, while ovaries expressed cyp19a1a and sox9b, but not amh. In adult testes, amh and sox9a were expressed in presumptive Sertoli cells. In adult ovaries, amh and cyp19a1a were expressed in granulosa cells surrounding the oocytes, and sox9b was expressed in a complementary fashion in the ooplasm of oocytes. The observed expression patterns of amh, sox9a, sox9b, and cyp19a1a in zebrafish correspond to the patterns expected if their regulatory interactions have been conserved with mammals. The finding that zebrafish sox9b and sox8 were not co-expressed with amh in oocytes excludes the possibility that amh expression in zebrafish granulosa cells is directly regulated by either of these two genes.     

Tonic effects of stationary luminous slits on the discharge rates of some locust visual interneurones

The presence of an illuminated slit in the visual field of a locust compound eye produced changes in the tonic discharge rate of the DCMD and three other visual interneurones, recorded in a connective. The DCMD discharge peaked initially in the range of low slit subtenses, but over a period of minutes of exposure its character changed so that there was a rise at high subtenses also. When the luminance of a slit of fixed subtense was increased in steps, there was an initial rise then a sharp fall in discharge, indicating an abrupt onset of inhibition. Lateral spread of inhibition could account for the peak in response to slits, at a subtense falling well within the acceptance angle of a single ommatidium. The results show the ability of some visual interneurones to maintain a changed level of discharge in the presence of a stationary object in the visual field of the eye.     

The effect of a complex of meditation exercises on the psychophysiological state of young men

Using a simple motor response, a complex sensorimotor response, and a tapping test, the effect of a complex of meditation exercises on the neuromuscular coordination in healthy male students who were preliminarily trained in methods of self-regulation based on meditation techniques was studied. As a result of a 6-min session of self-regulation, a considerable decrease (by 30% or more) in the time of a simple motor response and a complex sensorimotor response (due to a decrease in the latent time at constant motor time) and a simultaneous decrease in the number of errors, as well as a considerable increase in the result of the tapping test, were recorded. A short-term effect expressed in an increase in the rate and accuracy of sensorimotor responses can be a result of a change in the functional state of the nervous system under the impact of transcendental meditation techniques.     

Pathogenicity of two species of Fusarium on some cultivars of bean in greenhouse

Twenty isolates of Fusarium oxysporum and F. solani were isolated from the infected roots of bean in different farms of east Azarbaijan and Tehran Provinces and their pathogenicity determined. Most isolates of the fungi were identified as F. oxysporun. They caused root rot, yellowing and wilting of bean in the field. In this test, the roots of 6 cultivars of bean seedlings soaked in suspension of the 7 isolates of the fungi (a1, Gogan, a2, Bilverdi, a3, Savojbolagh-Hashtgerd, a4, field of Agr. Coll. a5, Khomein, a6, Ramjin of F. oxysporum and a7 of F. solani of Varamin, Iran) for 5 minute (106 spores/ml.) then transplanted into the sterilized soil in 4 pots (as replication). For control (a8) the roots soaked in distilled water. The results showed that percentage average of necrotic roots and crowns of isolates al, a2, a3, a5, a6, a7 was %20.31 in group a, a4 was %43.52 in group b and a8 was %2.77 in group c after 3 weeks. The isolate a4 (from the field of Agricultural College, Karaj) was more infectious than the other because it caused wilting, yellowing the leaves and decreased the growth very soon, followed by a5 with %25.32 rate was more pathogenic. Bean cultivar Goli-Red was more tolerant with %10.02 than the others of 16.29 (Naz Red) to 25.15 percent of necrotic the roots & stems.     

Lentivirus-mediated overexpression of microRNA-199a inhibits cell proliferation of human hepatocellular carcinoma

microRNA-199a (miR-199a) is a highly conserved miRNA, always deregulated in numerous human tumors. The results of microarray analysis indicated that miR-199a was frequently downregulated in hepatocellular carcinoma (HCC). The expression levels of miR-199a in 11 pairs of matched HCC neoplastic and adjacent non-neoplastic tissues, 5 HCC cell lines and liver cell line L02 were examined by quantitative real-time PCR analysis. We found miR-199a was significantly down-regulated in HCC tissues when compared with pair-matched adjacent non-tumor tissues. We also found the expression level of miR-199a was also substantially decreased in several human HCC cell lines including SMMC-7721, BEL-7402, BEL-7701, MHCC97H, and HepG2. To investigate the role of miR-199a in tumorigenesis, we developed a lentiviral vector for the expression of pre-miR-199a (Lenti-miR-199a). Lenti-miR-199a inhibited HCC cell proliferation in vitro and in vivo. Compared to parental cells or cells transfected with a control vector, the overexpression of microRNA-199a in the HCC cell lines HepG2 stably was showed to reduce cell proliferation in vitro and in vivo. Luciferase reporter assay revealed the regulation of miR-199a on 3’-UTR of HIF-1α. Further investigation confirmed that miR-199a significantly reduced the endogenous protein level of HIF-1α in hypoxia. MiR-199a inhibits cell proliferation in vitro and in vivo partly through down-regulation of HIF-1α in human HCC. Thus, these studies provide an important new insight into the pathogenesis of human HCC and it may open a new perspective for the development of effective gene therapy for human HCC.     

SELDI-TOF-MS Proteomic Profiling of Serum,Urine, and Amniotic Fluid in Neural Tube Defects

Neural tube defects (NTDs) are common birth defects, whose specific biomarkers are needed. The purpose of this pilot study is to determine whether protein profiling in NTD-mothers differ from normal controls using SELDI-TOF-MS. ProteinChip Biomarker System was used to evaluate 82 maternal serum samples, 78 urine samples and 76 amniotic fluid samples. The validity of classification tree was then challenged with a blind test set including another 20 NTD-mothers and 18 controls in serum samples, and another 19 NTD-mothers and 17 controls in urine samples, and another 20 NTD-mothers and 17 controls in amniotic fluid samples. Eight proteins detected in serum samples were up-regulated and four proteins were down-regulated in the NTD group. Four proteins detected in urine samples were up-regulated and one protein was down-regulated in the NTD group. Six proteins detected in amniotic fluid samples were up-regulated and one protein was down-regulated in the NTD group. The classification tree for serum samples separated NTDs from healthy individuals, achieving a sensitivity of 91% and a specificity of 97% in the training set, and achieving a sensitivity of 90% and a specificity of 97% and a positive predictive value of 95% in the test set. The classification tree for urine samples separated NTDs from controls, achieving a sensitivity of 95% and a specificity of 94% in the training set, and achieving a sensitivity of 89% and a specificity of 82% and a positive predictive value of 85% in the test set. The classification tree for amniotic fluid samples separated NTDs from controls, achieving a sensitivity of 93% and a specificity of 89% in the training set, and achieving a sensitivity of 90% and a specificity of 88% and a positive predictive value of 90% in the test set. These suggest that SELDI-TOF-MS is an additional method for NTDs pregnancies detection.     

A characteristic Mls-1a response precedes Mls-1a anergy in vivo

T cells expressing V beta 6 variable gene segments of the T cell receptor undergo blast formation and divide in mice after injection of lymphoid cells bearing minor lymphocyte-stimulating (Mls)-1a gene products. This in vivo Mls-1a response resembles in vitro Mls-1a stimulation; it is dose dependent, not MHC-class II haplotype restricted, but requires expression of functional IE gene products. The in vivo Mls-1a response is followed by a complete and specific in vivo Mls-1a anergy and a partial in vitro Mls-1a anergy. The measurement of a Mls-1a response in vivo and of the establishment of in vivo anergy to it provides a convenient method to assay Mls-1a reactivity of T cells in vivo on a cell-by-cell basis in terms of cell surface phenotype, size, and mitotic activity.     

Insulin and fructose regulate malic enzyme activity by different processes

A comparison of the regulatory processes controlling hepatic malic enzyme activity following treatment of diabetic rats with insulin or with a high fructose diet demonstrated several important differences. Insulin treatment caused a 50-fold increase in activity, due to a 12-fold increase in enzyme quantity and a 4-fold increase in specific activity(units/nmol). Dietary fructose caused a 3-fold increase in enzyme activity, due to a 3-fold increase in enzyme quantity, with no change in the specific activity of the enzyme. Thus, while fructose initiated a minor increase in malic enzyme activity, insulin was more effective, causing a substantially greater increase in enzyme activity and activating a hormone specific alteration in the catalytic activity of each enzyme molecule.     

A representative model of the hierarchic structure of human populations]

The paper deals with the concept of a hierarchy population. The population is hierarchial, if it can be divided into a certain amount of subpopulations in such a way that the set may naturally break into classes (levels). A migration may exist from each sub-population or into a higher one. Such population structures are frequently encountered among the human populations. It is shown that in a hierarchial population a selection is more efficient than in a non-subdivided one. In this respect the role of small populations in evolution is suggested. It was possible to demonstrate that in a hierarchial population there was a higher degree of polymorphism, a higher velocity of the evolutional process, that in a non-subdivided population of the same size. Besides, the level of polymorphism in the hierarchial population increases monotomously with the growth of the amount of generations during rather a long period of time.     

Mon1a protein acts in trafficking through the secretory apparatus

Mon1a was originally identified as a modifier gene of vesicular traffic, as a mutant Mon1a allele resulted in increased localization of cell surface proteins, whereas reduced levels of Mon1a showed decreased secretory activity. Here we show that Mon1a affects different steps in the secretory pathway including endoplasmic reticulum-to-Golgi traffic. siRNA-dependent reduction of Mon1a levels resulted in a delay in the reformation of the Golgi apparatus after Brefeldin A treatment. Endoglycosidase H treatment of ts045VSVG-GFP confirmed that knockdown of Mon1a delayed endoplasmic reticulum-to-Golgi trafficking. Reductions in Mon1a also resulted in delayed trafficking from Golgi to the plasma membrane. Immunoprecipitation and mass spectrometry analysis showed that Mon1a associates with dynein intermediate chain. Reductions in Mon1a or dynein altered steady state Golgi morphology. Reductions in Mon1a delayed formation of ERGIC-53-positive vesicles, whereas reductions in dynein did not affect vesicle formation. These data provide strong evidence for a role for Mon1a in anterograde trafficking through the secretory apparatus.