摘要:

AbstractMultiparametric flow cytometry was used to analyze the development of the endosperm in Zea mays L. during the period from 8 to 20 days after pollination (dap). Nuclear size, DNA content per nucleus, and frequencies of nuclei with varying properties were measured in preparations that included all of the endosperm nuclei of single kernels of the inbred strain Al88. Characteristics of nuclear populations from different kernels on the same ear showed minimal variation. The dynamic changes of non‐mitotic cells involved in endosperm development consisted of alternating periods of DNA replication with non‐replication. Seven rounds of DNA replication had occurred in some nuclei in the later developmental stages with the rate averaging approximately one round per 24‐hour period. Analysis of the DNA levels in the nuclei showed an exact doubling pattern indicating an endoreduplication process, that is, replication of the entire genome during each round. The loosely organized polytenization of the chromatin occurred to varying extents among the nuclei within an endosperm. A weak positive correlation existed between DNA content and size of nuclei suggesting that DNA increases and nuclear growth may not be highly coordinated in this tissue. Increased proportions of the larger nuclei occurred in the later stages of endosperm development. Considering the entire endosperm, the average DNA content per nucleus at the 15‐dap peak level was approximately 12.8 C constituting a 2.7‐fold overall increase f

ISSN:0192-253X    

DOI:10.1002/dvg.1020110202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe construction of cell hairs (trichomes) on the wings ofDrosophilaoccurs in synchrony on 30,000 cells over a period of about 20 hr. Changes in both morphology and patterns of protein synthesis occur rapidly during this time period. In this report we describe the use of stressinduced (heat shock) abnormalities in morphogenesis to provide further details on the stepwise processes of differentiation within single wing cells. A cartoon summary of the overall process and a discussion of some possible mechanisms is included.

ISSN:0192-253X    

DOI:10.1002/dvg.1020110203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe first step in a genetic analysis of aging is to identify and characterize the genetic mutants and their controls that will be used. Such mutants or strains are initially identified by their effect on the life span. Yet many genetic interventions are known to have some effect on the life span without necessarily affecting the aging process. It is therefore necessary to prove that one is actually dealing with an aging mutant before one draws strong inferences from the data. Casarett's rules provide an operational test for doing so, relying as they do on the comparison of aging biomarkers in the experimental and reference strains. We show that our previously described genetically based long‐lived NDC‐L strain and its normal‐lived NDC‐R control strain differ only in the chronological age of expression of two behavioral and three physiological functional age biomarkers. They do not differ in the sequence or the physiological age of expression of these biomarkers. These two strains comply with the Casarett rules and thereby comprise a valid tool with which to conduct a comparative genetic analysis of aging. The implications of the available data are discussed, including the possibility that aging in these strains ofDrosophila melanogastermay be the result of a multiphasic developmental

ISSN:0192-253X    

DOI:10.1002/dvg.1020110204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe interaction of reactive oxygen metabolites with DNA is well characterized and may result in mutagenesis, chromosome aberrations, and modulation of gene expression. Superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH‐Px) catalyze enzymatic reactions to remove oxidant stresses, particularly O2−and H2O2. The role of these enzymes during in utero development of the embryo and the developmental pattern of expression of the embryonic genes encoding them is not known. We examined the in utero developmental expression and activity of the three free‐radical–metabolizing enzymes in mice. We collected mouse fetuses at different stages of development and examined total RNA populations by Northern and slot blots using gene‐specific cDNA probes. In addition to quantifying the probe‐specific RNAs, activities of the three enzymes were also evaluated on the same tissue samples.The gene‐specific RNAs and the associated enzyme activities are detectable with somite formation (day 8 postcoitus [p.c.]) in mice. The relative RNA values for each of the genes studied are higher in in utero stages as compared with the adult. The specific activities of these enzymes, on the other hand, follow a characteristic increase with development and growth. The relative RNA levels for each of the genes studied are higher during in utero growth and development than the relative enzyme activity values (between day 8 and day 18, third trimester) in the liver and carcass. This may suggest that the mRNA specific to these genes may accumulate in utero and are not translated immediately. Such accumulating transcripts are translated efficiently after birth, when these enzyme are particularly needed with the advent of aerobi

ISSN:0192-253X    

DOI:10.1002/dvg.1020110205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractA series of constructs containing the developmentally regulated soybean lectin gene (Le1) were used to transform tobacco plants in order to assess developmental and quantitative regulation conferred by flanking sequences. The largest of the lectin constructs contained approximately 3,00 base pairs (bp) of Le1 5′ flanking region and 1,500 bp of the 3′ flanking region. The smallest construct contained no 5′ flanking region and 194 bp of the 3′ flanking region. ELISA assays of lectin in individual tobacco seeds and Southern blot analyses confirmed that most constructs were inherited as unique insertion events. Maximal expression of Le1 required more than 338 bp of 5′ sequence, indicating that far upstream factors are involved in quantitative control of lectin expression. Lectin expression declined more than 80% between deletions with 1,700 versus 338 bp of 5′ flanking sequence. In contrast, developmental control of lectin expression was maintained by Le1 inserts with only 190 bp of 5′ sequence. The lectin promoter offers a potential means to target high levels of gene expression to the developing seeds of soybean or other dicotyle

ISSN:0192-253X    

DOI:10.1002/dvg.1020110206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractWe have analyzed the expression of endogenous murine genes and of transfected human fetalAγ globin gene in GM 979, a mouse erythroleukemia line which produces adult as well as embryonic globins. Optimal induction of the endogenous murine adult globin genes was obtained with DMSO or HMBA while the ϵyand βh1 embryonic genes were preferentially induced by butyrate. Similarly, the transferred humanAγ globin gene was preferentially induced by butyrate. These results as well as previous observations in vivo or in erythroid cell cultures suggest that butyrate preferentially induces the expression of fetal globin ge

ISSN:0192-253X    

DOI:10.1002/dvg.1020110207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

ISSN:0192-253X    

DOI:10.1002/dvg.1020110201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY