906 resultados para isolation-by-distance


Relevância:

40.00% 40.00%

Publicador:

Resumo:

Supplement to his Tracts physical and mathematical.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

Endoparasitoid insects introduce maternal factors into the body of their host at oviposition to suppress cellular defences for the protection of the developing parasitoid. We have shown that transient expression of polydnavirus genes from a hymenopteran parasitoid Cotesia rubecula (CrPDV) is responsible for the inactivation of hemocytes from the lepidopteran host Pieris rapae. Since the observed downregulation of CrPDV genes in infected host tissues is not due to cis-regulatory elements at the CrV1 gene locus, we speculated that the termination of CrPDV gene expression may be due to cellular inactivation caused by the CrV1-mediated immune suppression of infected tissues. To test this assumption, we isolated an imaginal disc growth factor (IDGF) that is expressed in fat body and hemocytes, the target of viral infection and expression of CrPDV genes. Time-course experiments showed that the level of P. rapae IDGF is not affected by parasitization and polydnavirus infection. However, the amount of highly expressed genes, such as storage proteins, arylphorin and lipophorin, are significantly reduced following parasitization. (C) 2004 Elsevier Ltd. All rights reserved.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

Physiological and genetic studies with the ramosus (rms) mutants in garden pea (Pisum sativum) and more axillary shoots (max) mutants in Arabidopsis (Arabidopsis thaliana) have shown that shoot branching is regulated by a network of long-distance signals. Orthologous genes RMS1 and MAX4 control the synthesis of a novel graft-transmissible branching signal that may be a carotenoid derivative and acts as a branching inhibitor. In this study, we demonstrate further conservation of the branching control system by showing that MAX2 and MAX3 are orthologous to RMS4 and RMS5, respectively. This is consistent with the longstanding hypothesis that branching in pea is regulated by a novel long-distance signal produced by RMS1 and RMS5 and that RMS4 is implicated in the response to this signal. We examine RMS5 expression and show that it is more highly expressed relative to RMS1, but under similar transcriptional regulation as RMS1. Further expression studies support the hypothesis that RMS4 functions in shoot and rootstock and participates in the feedback regulation of RMS1 and RMS5 expression. This feedback involves a second novel long-distance signal that is lacking in rms2 mutants. RMS1 and RMS5 are also independently regulated by indole-3-acetic acid. RMS1, rather than RMS5, appears to be a key regulator of the branching inhibitor. This study presents new interactions between RMS genes and provides further evidence toward the ongoing elucidation of a model of axillary bud outgrowth in pea.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

The vaccines 1-2 and V4 are avirulent strains of Newcastle disease virus. Organ tropism of strain V4 has been determined and the virus has a predilection for the digestive tract. Tropism of strain 1-2 has not yet been determined. The objective of this study was to determine the distribution of strain 1-2 in various body organs and fluids following vaccination in comparison with V4. Four-week-old chickens were vaccinated by eye drop separately with these two avirulent strains. Virus isolation and the reverse transcription-polymerase chain reaction technique were employed to detect 1-2 and V4 viruses in various tissues and body fluids for 7 days following vaccination. Tissues from the respiratory tract showed earlier positive signals than tissues from other organs for chickens vaccinated with strain 1-2. Conversely, tissues from mainly digestive tract produced earlier positive signals than from respiratory tract and other organs from chickens vaccinated with strain V4. In early infection, strain 1-2 had preferential predilection for the respiratory tract and strain V4 for the digestive tract. Later after vaccination, other organs showed positive results from chickens vaccinated with both 1-2 and V4 strains. The differences in organ tropism observed in this study suggest that 1-2 may perform better than V4 as a live vaccine strain.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

Proliferation of legume nodule primordia is controlled by shoot-root signaling known as autoregulation of nodulation (AON). Mutants defective in AON show supernodulation and increased numbers of lateral roots. Here, we demonstrate that AON in soybean is controlled by the receptor-like protein kinase GmNARK (Glycine max nodule autoregulation receptor kinase), similar to Arabidopsis CLAVATA1 (CLV1). Whereas CLV1 functions in a protein complex controlling stem cell proliferation by short-distance signaling in shoot apices, GmNARK expression in the leaf has a major role in long-distance communication with nodule and lateral root primordia.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

The sequence-specific affinity chromatographic isolation of plasmid DNA from crude lysates of E. coli DH5α fermentations is addressed. A zinc finger-GST fusion protein that binds a synthetic oligonucleotide cassette containing the appropriate DNA recognition sequence is described. This cassette was inserted into the Smal site of pUC19 to enable the affinity isolation of the plasmid. It is shown that zinc finger-GST fusion proteins can bind both their DNA recognition sequence and a glutathione-derivatized solid support simultaneously. Furthermore, a simple procedure for the isolation of such plasmids from clarified cell lysates is demonstrated. Cell lysates were clarified by cross-flow Dean vortex microfiltration, and the permeate was incubated with zinc finger-GST fusion protein. The resulting complex was adsorbed directly onto glutathione-Sepharose. Analysis of the glutathione-eluted complex showed that plasmid DNA had been recovered, largely free from contamination by genomic DNA or bacterial cell proteins. © 2002 Wiley Periodicals, Inc.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

A tárgyalófelek elé kitett mobiltelefon alkalmazása előrejelzi a beszélgetőpartnerek versenyképességét a versenyképesség-mutatók alapján, javaslatokat adva a tárgyalás további menetére. Ez a vízió nyilván még futurisztikus, ám a csúcsvezetői nyilatkozatok rejtett szövegtartalma alapján következtetéseket levonni a képviselt szervezetek versenyképességi orientációira – ez már ma lehetőség. A GLOBE-projekt kultúrakutatási módszertanával, valamint szövegelemzési módszerekkel sikerült kimutatni a versenyképességet előrejelző hatalmi távolság és az intézményi kollektivizmus szövegbeli jeleit. Mindez eszközt jelenthet egyebek mellett a szervezetfejlesztéssel, hírszerzéssel, HR-gazdálkodással foglalkozó szakembereknek is. _______ The use of the mobile telephones laid in front of the negotiators during their conversations forecasts their indicators of competitiveness and gives suggestions for the further course of negotiation. This is obviously a futuristic vision, but drawing conclusions from the hidden content of top management narratives concerning the competitive cultural orientations of the represented organizations is a possibility that is already available. Using the culture research methodology of the GLOBE project as well as text analysis methods, it was possible to reveal narrative patterns both of the power distance, forecasting competitiveness, and of institutional collectivism. These findings may be useful tools for professionals, among others of organizational development, intelligence service and HR management.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

The purpose of this research was to compare the delivery methods as practiced by higher education faculty teaching distance courses with recommended or emerging standard instructional delivery methods for distance education. Previous research shows that traditional-type instructional strategies have been used in distance education and that there has been no training to distance teach. Secondary data, however, appear to suggest emerging practices which could be pooled toward the development of standards. This is a qualitative study based on the constant comparative analysis approach of grounded theory.^ Participants (N = 5) of this study were full-time faculty teaching distance education courses. The observation method used was unobtrusive content analysis of videotaped instruction. Triangulation of data was accomplished through one-on-one in-depth interviews and from literature review. Due to the addition of non-media content being analyzed, a special time-sampling technique was designed by the researcher--influenced by content analyst theories of media-related data--to sample portions of the videotape instruction that were observed and counted. A standardized interview guide was used to collect data from in-depth interviews. Coding was done based on categories drawn from review of literature, and from Cranton and Weston's (1989) typology of instructional strategies. The data were observed, counted, tabulated, analyzed, and interpreted solely by the researcher. It should be noted however, that systematic and rigorous data collection and analysis led to credible data.^ The findings of this study supported the proposition that there are no standard instructional practices for distance teaching. Further, the findings revealed that of the emerging practices suggested by proponents and by faculty who teach distance education courses, few were practiced even minimally. A noted example was the use of lecture and questioning. Questioning, as a teaching tool was used a great deal, with students at the originating site but not with distance students. Lectures were given, but were mostly conducted in traditional fashion--long in duration and with no interactive component.^ It can be concluded from the findings that while there are no standard practices for instructional delivery for distance education, there appears to be sufficient information from secondary and empirical data to initiate some standard instructional practices. Therefore, grounded in this research data is the theory that the way to arrive at some instructional delivery standards for televised distance education is a pooling of the tacitly agreed-upon emerging practices by proponents and practicing instructors. Implicit in this theory is a need for experimental research so that these emerging practices can be tested, tried, and proven, ultimately resulting in formal standards for instructional delivery in television education. ^