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     

Female-induced sexual arousal in male mice and rats: behavioral and testosterone response

Exposure of a male mouse to a female mouse separated from it by a holed partition induced specific behavior and an increase in blood testosterone in the male. The male made more approaches to the partition and spent more time at it. The time spent by the male mouse over the first 10 min at the partition, behind which an estrus female was placed, was increased sixfold compared to the time spent by a male mouse exposed to the vacant neighboring compartment; and 1.5-fold compared to that spent by a male mouse exposed to a nonreceptive female or a male. Increased blood testosterone level was detected at 20 min of exposure to a receptive female in winter and at 40 min in summer. No variation in blood testosterone levels in the male mouse exposed to a nonreceptive female or a male was observed. Similar response to a receptive female placed in the neighboring compartment was shown in a male rat. The time spent by the male rat at the partition was 12 times higher when there was an estrus female behind it than in control. Blood testosterone in the male rat increased in response to a female rat and did not change in response to a male rat indicating female-induced motivation. It was concluded that the partition time might serve as a quantitative measure of sexual motivation in the males and that the model of female-induced sexual arousal used was suitable for studying both motivational and hormonal components of sexual arousal in male mice and rats.     

MiR-34a inhibits the proliferation,migration, and invasion of oral squamous cell carcinoma by directly targeting SATB2

In various kinds of carcinomas, the special AT-rich sequence-binding protein 2 (SATB2) with its atypical expression promotes the metastasis and progression of the tumor, though in the oral squamous cell carcinoma (OSCC) its inherent mechanism and the status of SATB2 remain unclear. The role played by the SATB2 expression in the OSCC cell lines and tissue samples in the target of miR-34a downstream is the intended endeavor of this study. In te OSCCs the miR-34a expression was determined by quantitative real-time polymerase chain reaction (q-PCR), while the SATB2 expression in the cell lines and tissue samples in OSCC was analyzed with the q-PCR and the western blot. Studies in both in vitro and in vivo of the effects of miR-34a on the initiation of OSCC were conducted. As a direct target of the miR-34a the SATB2 was verified with the luciferase reporter assay. In cases where the miR-34a levels were low, the SATB2 in OSCCs seemed to be overexpressed. Besides, both in the in vitro and in vivo a suppression of migration, invasion, and cell growth was caused by miR-34a by down regulating the SATB2 expression. The SATB2 being a direct target of miR-34a was confirmed by the cotransfection of miR-34a mimics specifically the decrease in the expression of luciferase of SATB2–3′UTR-wt reporter. As a whole, our study confirmed the inhibition of miR-34a in the invasion, proliferation, and migration of the OSCCs, playing a potential tumor suppressor role with SATB2 as its downstream target.     

Wnt7a,frequently silenced by CpG methylation,inhibits tumor growth and metastasis via suppressing epithelial-mesenchymal transition in gastric cancer

Wnt7a is a member of the Wnt family and has been reported to be involved in the carcinogenesis and progression of many types of human cancer. However, little is known about Wnt7a expression and function in gastric cancer (GC). In the present study, Wnt7a expression in GC tissues and cells was investigated, the correlation between Wnt7a expression and the prognosis was also examined. The effects of Wnt7a on proliferation, invasion, and metastasis were evaluated in vitro and in vivo. Furthermore, the expression of epithelial-mesenchymal transition (EMT) markers and hypermethylation of the Wnt7a promoter were both detected. Wnt7a was downregulated in GC and its expression was associated with poor prognosis of patients with GC. Moreover, upregulation of Wnt7a significantly suppressed the growth, invasion, and metastasis abilities of GC cells in vitro and in vivo. Mechanistically, Wnt7a was found to inhibit EMT process of GC cells. In addition, the reducing expression of Wnt7a was due to methylation of 5′-CpG island within the promoter. Furthermore, the tumor suppressor role of Wnt7a is independent of canonical Wnt/β-catenin signaling in GC cells. In conclusion, our findings demonstrated that Wnt7a could be used as a potential diagnostic marker and target for GC management.     

Lipoprotein(a) levels, apo(a) isoform size, and coronary heart disease risk in the Framingham Offspring Study

The aim of this study was to assess the independent contributions of plasma levels of lipoprotein(a) (Lp(a)), Lp(a) cholesterol, and of apo(a) isoform size to prospective coronary heart disease (CHD) risk. Plasma Lp(a) and Lp(a) cholesterol levels, and apo(a) isoform size were measured at examination cycle 5 in subjects participating in the Framingham Offspring Study who were free of CHD. After a mean follow-up of 12.3 years, 98 men and 47 women developed new CHD events. In multivariate analysis, the hazard ratio of CHD was approximately two-fold greater in men in the upper tertile of plasma Lp(a) levels, relative to those in the bottom tertile (P < 0.002). The apo(a) isoform size contributed only modestly to the association between Lp(a) and CHD and was not an independent predictor of CHD. In multivariate analysis, Lp(a) cholesterol was not significantly associated with CHD risk in men. In women, no association between Lp(a) and CHD risk was observed. Elevated plasma Lp(a) levels are a significant and independent predictor of CHD risk in men. The assessment of apo(a) isoform size in this cohort does not add significant information about CHD risk. In addition, the cholesterol content in Lp(a) is not a significant predictor of CHD risk.     

Murine numb regulates granule cell maturation in the cerebellum

Notch is a key regulator of vertebrate neurogenesis and the cytoplasmic adaptor protein Numb is a modulator of the Notch signaling pathway. To address the role of murine Numb in development of the central nervous system, we used a conditional gene ablation approach. We show that Numb is involved in the maturation of cerebellar granule cells. Although the specification of neural cell fates in the cerebellum is not affected in the absence of Numb, the transition from a mitotic progenitor to a mature granule cell is aberrant and migration of postmitotic granule cells to the internal granule cell layer is delayed. In some animals, this results in a complete agenesis of granule cells and a strong ataxia. We confirmed these findings in vitro and found that Numb-deficient cerebellar progenitor cells show a marked delay in granule cell maturation. Our results suggest that Numb plays a role in the transition of a mitotic progenitor to a fully differentiated granule cell in the cerebellum. In addition, the maturation of Purkinje cells is also delayed in Numb-deficient mice.     

Ewens' sampling formula and related formulae: combinatorial proofs, extensions to variable population size and applications to ages of alleles

Ewens' sampling formula, the probability distribution of a configuration of alleles in a sample of genes under the infinitely-many-alleles model of mutation, is proved by a direct combinatorial argument. The distribution is extended to a model where the population size may vary back in time. The distribution of age-ordered frequencies in the population is also derived in the model, extending the GEM distribution of age-ordered frequencies in a model with a constant-sized population. The genealogy of a rare allele is studied using a combinatorial approach. A connection is explored between the distribution of age-ordered frequencies and ladder indices and heights in a sequence of random variables. In a sample of n genes the connection is with ladder heights and indices in a sequence of draws from an urn containing balls labelled 1,2,...,n; and in the population the connection is with ladder heights and indices in a sequence of independent uniform random variables.     

Fishery policy when considering the future opportunity of harvesting

Free access to a common pool of resource in a country may lead to over-exploitation and sacrifice future opportunities of harvesting. As such, the protection of a common fishery resource is worth investigating. In this paper we develop a two-period model and a multi-period model to analyze the optimal inter-temporal utilization of a finite resource of stock and propose to impose a tax on the harvest rate as an efficient mechanism with an aim at economic sustainability by incorporating the future opportunity of harvesting into the models as a major component of social objectives. The sensitivity analysis of the two-period model shows that (1) labor inputs for harvesting in Period 1 should be reduced, the biomass of fishery stock will increase, but the harvesting in Period 2 should be amplified and the biomass of fishery stock in Period 2 will not be affected if the current generation owns a higher valuation on the future opportunity of harvesting; (2) a higher internal regeneration rate leads to higher harvesting in each period and a higher level of fishery stock in Period 1, but an uncertain level of fishery stock in Period 2; (3) with a higher discount rate the harvesting in Period 1 should increase, but the harvesting in Period 2 should fall and the level of fishery stock in each period will be reduced; (4) a higher fish price in Period 1 leads to higher harvesting in Period 1, but reduced harvesting in Period 2. As a consequence, the level of fishery stock in each period will be reduced; (5) the effect of a change in fish prices in Period 2 on the harvesting and the level of fishery stock in Period 1 is uncertain, but the change in fish prices in Period 2 gives a positive effect on harvesting in Period 2 and a negative effect on the level of fishery stock in Period 2; (6) higher labor wages in Period 1 lead to lower harvesting, but a higher level of fishery stock in Period 1. This encourages an increase in harvesting in Period 2 and leads to a higher level of fishery stock in Period 2; and (7) a change of the labor wage in Period 2 affects the harvesting and the level of fishery stock in Period 1 indecisively, but it gives negative effects on the harvesting in Period 2 and positive effects on the level of fishery stock in Period 2.     

Ghrelin in ocular pathophysiology: From the anterior to the posterior segment

Ghrelin is a 28 amino acid acylated peptide produced in several organs that binds the growth hormone secretagogues receptor type 1a (GHSR-1a). It acts over a wide range of systems, e.g. the endocrine, cardiovascular, musculoskeletal and immune systems and the eye. The aim of this work is to review the physiologic and pathologic implications of the ghrelin-GHSR-1a in the eye. A systematic revision of studies published between 2000 and 2013 in English, Spanish or Portuguese in MEDLINE, EMBASE and Scopus was performed. Search words used included: ghrelin, GHSR-1a, ocular production, iris muscular kinetics, ciliary body, glaucoma, retinopathy and uvea. The production of ghrelin by the ocular tissue has been detected both in the anterior and posterior segments, as well as the presence of GHSR-1a. This peptide promotes the relaxation of the iris sphincter and dilator muscles, being this effect independent from GHSR-1a and dependent on prostaglandins release in the first case and dependent on GHSR-1a in the second. Regarding ocular pathology, ghrelin levels in the aqueous humor appear to be decreased in individuals with glaucoma. Moreover, ghrelin has been shown to decrease the intraocular pressure in animal models of ocular hypertension through GHSR-1a. In the posterior segment, the ghrelin-GHSR-1a system interferes with the development of oxygen-induced retinopathy, being protective in the vaso-obliterative phase and deleterious in the vaso-proliferative stage of the disease. Thus, the ghrelin-GHSR-1a system presents as a possible local regulatory mechanism in the eye, with pathophysiological implications, constituting a target for future clinical and therapeutic research and interventions.     

Systematic root anatomy of Asparagales and other monocotyledons

Root anatomy of several taxa of Asparagales and some taxa formerly included in Asparagales is described in a systematic context together with a literature review. The presence of a dimorphic outer layer with long and short cells is widespread in monocotyledons, indicating that it originated early in the monocot lineage, but whereas this layer is rhizodermal in most monocotyledons, in Asparagales and Araceae it is usually hypodermal. There may be a correlation between the presence of a velamen or a persistent rhizodermis in many Asparagales and Araceae and the presence of a dimorphic hypodermal layer. Many other root anatomical characters, such as the presence of vascular bundles in the central pith and a multi-layered sclerenchymatous cylinder, are probably xeromorphic and developed convergently.     

Intragenic codon bias in a set of mouse and human genes

To better conceptualize the mechanism underlying the evolution of synonymous codons, we have analysed intragenic codon usage in chosen "regions" of some mouse and human genes. We divided a given gene into two regions: one consisting of a trinucleotide repeat (TNR) and the other consisting of the "rest of the coding region" (RCR). Usually, a TNR is composed of a repetitive single codon, which may reflect its frequency in a gene. In contrast, a non-random frequency of a codon in the RCR versus TNR (or vice versa) of a gene should indicate a bias for that codon within the TNR. We examined this scenario by comparing codon frequency between the RCR and the cognate TNR(s) for a set of human and mouse genes. A TNR length of six amino acids or more was used to identify genes from the Genbank database. Twenty nine human and twenty one mouse genes containing TNRs coding for nine different amino acid runs were identified. The ratio of codon frequency in a TNR versus the corresponding RCR was expressed as "fold change" which was also regarded as a measure of codon bias (defined as preferential use either in TNR or in RCR). Chi-square values were then determined from the distribution of codon frequency in a TNR vs. the cognate RCR. At p<0.001, 22% and 27%, respectively, of human and mouse TNRs showed codon bias. Greater than 40% of the TNRs (29 out of 69 in human, and 18 of 42 in mouse) showed codon bias at p<0.05. In addition, we identify eight single-codon TNRs in mouse and ten in human genes. Thus, our results show intragenic codon bias in both mouse and human genes expressed in diverse tissue types. Since our results are independent of the Codon Adaptation Index (CAI) and starvation CAI, and since the tRNA repertoire in a cell or in a tissue is constant, our data suggest that other constraints besides tRNA abundance played a role in creating intragenic codon bias in these genes.     

Vasopressin 1a receptor knockout mice have a subtle olfactory deficit but normal aggression

Two receptors for vasopressin (Avp) are expressed in the brain, the Avp 1a receptor (Avpr1a) and the Avp 1b receptor (Avpr1b). To investigate the role of Avpr1a in behaviors in mice more extensively, we generated a line of mice lacking a functional Avpr1a (knockout, Avpr1a(-/-)). We first performed a baseline phenotypic screen of the Avpr1a knockouts followed by a more detailed analysis of their circadian rhythms and olfactory function. When free-running in constant darkness, the Avpr1a(-/-) mice have a longer circadian tau than the wild types. There are also subtle olfactory deficits in Avpr1a(-/-) mice as measured in an olfactory habituation/dishabituation test and in the discrimination of female urine from male urine using an operant testing paradigm. An extensive body of research has shown that manipulation of the Avpr1a alters behavior, including aggression and social recognition. Therefore, we expected profound behavioral deficits in mice lacking the Avpr1a gene. Contrary to our expectations, social aggression, anxiety-like behavior and social recognition are unaffected in this line of Avpr1a knockout mice. These data suggest either that the Avpr1a is not as critical as we thought for social behavior in mice or, more likely, that the neural circuitry underlying aggression and other social behaviors compensates for the life-long loss of the Avpr1a. However, the olfactory deficits observed in the Avpr1a(-/-) mice suggest that Avp and Avpr1a drugs may affect behavior, in part, by modulation of chemosensory systems.     

The Late Triassic Phytosaur Mystriosuchus Westphali, With A Revision of the Genus

Mystriosuchus westphali is based on a large, well-preserved cranium and a snout fragment from the Stubensandstein (Norian) of south-west Germany. The hypodigm is redescribed and new or poorly known cranial structures in phytosaurs are discussed. For the first time, the presence of a premaxillary crest is substantiated in a phytosaur. The type specimen shows a supernumerary occipital element (='tabular') that is probably fused to the parietal in other phytosaurs, and an orbitosphenoid. A computerised parsimony analysis confirms the hypothesis that Mystriosuchus is nested within Pseudopalatinae, the most derived clade of phytosaurs, and thus does not fall within basal phytosaurs. Mystriosuchus is characterised by five unique features (slit-like interpremaxillary fossa, triangular cross-section of the postorbito-squamosal bar, strongly reduced posttemporal fenestra, and two features of the cranial sculpture), plus eight synapomorphies that also occur in some more distantly related taxa. Mystriosuchus westphali is diagnosed by, among other apomorphies, a distinct premaxillary crest, a squamosal-proo¨tic contact, absence of a posterior process of the squamosal, and a slit-like posttemporal fenestra. The type species Mystriosuchus planirostris shows, most significantly, the naris facing forward anteriorly and upward posteriorly, and the longest rostrum and the highest degree of depression of the supratemporal opening in any phytosaur. Mystriosuchus exemplifies a common pattern in phytosaurids in being a genus that includes a gracile, elongated, slender-snouted and a more robust species with a broader, often crested snout. This study demonstrates that a detailed analysis of the cranial anatomy and the rigorous application of cladistic principles to identified character states help to clarify current inconsistencies in the taxonomy and nomenclature of phytosaurs.     

Mutation of the maize sbe1a and ae genes alters morphology and physical behavior of wx-type endosperm starch granules

In maize, three isoforms of starch-branching enzyme, SBEI, SBEIIa, and SBEIIb, are encoded by the Sbe1a, Sbe2a, and Amylose extender (Ae) genes, respectively. The objective of this research was to explore the effects of null mutations in the Sbe1a and Ae genes alone and in combination in wx background on kernel characteristics and on the morphology and physical behavior of endosperm starch granules. Differences in kernel morphology and weight, starch accumulation, starch granule size and size distribution, starch microstructure, and thermal properties were observed between the ae wx and sbe1a ae wx plants but not between the sbe1a wx mutants when compared to wx. Starch from sbe1a ae wx plants exhibited a larger granule size with a wider gelatinization temperature range and a lower endotherm enthalpy than ae wx. Microscopy shows weaker iodine staining in sbe1a ae wx starch granules. X-ray diffraction revealed A-type crystallinity in wx and sbe1a wx starches and B-type in sbe1a ae wx and ae wx. This study suggests that, while the SBEIIb isoform plays a dominant role in maize endosperm starch synthesis, SBEI also plays a role, which is only observable in the presence of the ae mutation.     

Matrix metalloprotease 16 expression is downregulated by microRNA-146a in spontaneously differentiating Caco-2 cells

Cellular differentiation in the gut is vital in maintaining the cellular and functional specialization of the epithelial layer. MicroRNAs (miRNAs) have recently emerged as one of the key players in orchestrating the differentiation process in the gut. Using the spontaneously differentiating Caco-2 cell line, we observed an increased expression of miR-146a but not miR-146b in the course of differentiation. Bioinformatic analyses revealed that the membrane type matrix metalloprotease 16 (MMP16, MT3-MMP) was a predicted target of miR-146a and a decrease in the mRNA and protein expression of MMP16 was observed in the course of differentiation. Transfection of a luciferase reporter vector containing the 3'UTR of MMP16 showed decreased luciferase activity due to miR-146a expression. With forced expression of miR-146a in undifferentiated Caco-2 cells, a decrease in the mRNA and protein levels of MMP16 and a lower gelatinase activity in a gelatin zymogram were observed. Additionally, forced expression of miR-146a in HT-29 colon cancer cells also resulted in decreased expression of MMP16, along with a decrease in the invasion through Matrigel. Taken together, we have shown here that MMP16 is regulated by miR-146a in spontaneously differentiated Caco-2 cells. As MMP16 activates the zymogen of MMP2, which is known to degrade extracellular matrix proteins, the regulation of MMP16 by miR-146a may account, at least in part, for lower motility of well-differentiated cells.     

Short Communication: The effect of CYP1A1 induction on the formation of benzo a pyrene adducts in liver and lung DNA and plasma albumin in rats exposed to benzo a pyrene:adduct quantitation by immunoassay and an HPLC method

Induction of cytochrome P450 enzymes by exposure to polycyclic aromatic hydrocarbons (PAH) can result in both decreased or increased PAH adduct levels. The lung is a main target site for PAH-carcinogenesis. By HPLC determination of B[ a]P-r-7, t-8-dihydrodiol, t-9, 10-epoxide (BPDE-I)-DNA adducts in rat, the level of the ultimate carcinogenic B[a]P-metabolite was higher in lungs than in liver. However, measured by immunoassay, the total benzo[a]pyrene (B[a]P)-DNA adduct levels were higher in liver than in lungs. Induction of CYP1A1 in vivo in rat by repeated i.p. doses of methylcholanthrene (MC) prior to a single dose of B[a]P resulted in a 2.4 times increase in CYP1A1 activity in liver tissue and 1.5 times higher levelsof total B[a]P-DNA adducts in lung and liver compared with controls which only received B[a]P. Increased levels of BPDE-I-DNA adducts were significantly correlated to increased CYP1A1 activity in induced lung tissue but not in liver. The times to reach maximum adduct levels were similar for both controls and MC-induced rats in both lung and liver,and plasma albumin. The BPDE-I-albumin adducts reached a maximum level around 1 day after B[a]P exposure and could not be used as a reliable marker of the short term PAH exposure in this study.     

Is there a weak H‐bond → LBHB transition on tetrahedral complex formation in serine proteases?

The transformation of a weak hydrogen bond in the free enzyme into a low-barrier hydrogen bond (LBHB) in the tetrahedral intermediate has been suggested as an important factor facilitating catalysis in serine proteases. In this work, we examine the structure of the H-bond in the Asp102-His57 diad of serine proteases in the free enzyme and in a covalent tetrahedral complex (TC) with a trifluoromethylketone inhibitor. We apply ab initio quantum mechanical calculations to models consisting of a large molecular fragment of the enzyme active site, and the combined effect of the rest of the protein body and the solvation by surrounding bulk water was simulated by a self-consistent reaction field method in our novel QM/SCRF(VS) approach. Potential profiles of adiabatic proton transfer in the Asp102-His57 diad in these model systems were calculated. We conclude that the hydrogen bond in both the free enzyme and in the enzyme-inhibitor TC is a strong ionic asymmetric one-well hydrogen bond, in contrast to a previous suggestion that it is a weak H-bond in the former and a double-well LBHB in the latter.     

Effects of cultivation practice on floristic and flowering diversity of spontaneously growing plant species on arable fields

In the past, the floristic diversity of arable fields has been described in terms of species diversity (SD) and their degree of coverage (C), but never in combination with the recording of the actually flowered species (FS) and their flowering intensity (FI) to striking differences in the cultivation methods on arable land. In relation to SD and C, however, FS and FI may provide important additional information on the functional biodiversity of fields. The aim was therefore to investigate the effects of (a) conventional, (b) organic, and (c) smallholder (never application of herbicides) on the floristic diversity. Using a region in Germany, we investigated SD, C, FS, and FI synchronously in (a), (b), and (c), by 356 vegetation surveys (5 × 5 m plots) conducted in spring and summer in 2019 in winter cereals. Statistical tests were used to analyze the differences between (a), (b), and (c). The medians were used to compare the floristic diversity of (a), (b), and (c) and finally relationships of FS and FI to SD were analyzed in relation to the cultivation methods. Significant differences in SD, C, FS, and FI were found between the (a), (b), and (c) in spring and summer characterized by sharp declines from (c) to (b) to (a). A drastic reduction in floristic diversity from (c) 100 to (b) 52 to (a) 3 was determined. Plants in flower (FS, FI) were very poorly in (a), moderately well to well in (b), and well to very well represented in (c). (C) to (a) was characterized by a sharp decline and from (a) to (b) by sharp increase in floristic diversity. With current acreage proportions of (a) in mind, this would affect, about one third of land area in Germany, associated with a drastic reduction in functional biodiversity for insects.