273 research outputs found
Inheritance of seedlessness in grapevine (Vitis vinifera L.)
Despite considerable efforts made by breeders for over 70 years, inheritance of seedlessness in grapevine is not clearly defined. None of the numerous hypotheses proposed until now is satisfying, whether they are based on recessive or dominant genes. We measured precisely the phenotypic expression of the seeded/seedless character in a progeny obtained by crossing two partially seedless selections and using in ovulo and in vitro culture to rescue embryos. We propose the hypothesis that inheritance of seedlessness in grapevine is based on a complex system whereby the expression of three independently inherited recessive genes is controlled by a dominant regulator gene. This hypothesis was compared to other results published in the scientific literature and appeared coherent enough to be used as a theoretical basis for further work on seedlessness inheritance in grapevine. Attempts to explain the control of seedlessness involve interactions with endogenous gibberellins. The consequences of such a model for the development of breeding programs for seedless table grapes, and particularly for the use of molecular biology techniques, are discussed
Loss of AP-3 function affects spontaneous and evoked release at hippocampal mossy fiber synapses
Synaptic vesicle (SV) exocytosis mediating neurotransmitter release occurs
spontaneously at low intraterminal calcium concentrations and is stimulated by
a rise in intracellular calcium. Exocytosis is compensated for by the
reformation of vesicles at plasma membrane and endosomes. Although the adaptor
complex AP-3 was proposed to be involved in the formation of SVs from
endosomes, whether its function has an indirect effect on exocytosis remains
unknown. Using mocha mice, which are deficient in functional AP-3, we identify
an AP-3-dependent tetanus neurotoxin-resistant asynchronous release that can be
evoked at hippocampal mossy fiber (MF) synapses. Presynaptic targeting of the
tetanus neurotoxin-resistant vesicle soluble N-ethylmaleimide-sensitive factor
attachment protein receptor (SNARE) tetanus neurotoxin-insensitive
vesicle-associated membrane protein (TI-VAMP) is lost in mocha hippocampal MF
terminals, whereas the localization of synaptobrevin 2 is unaffected. In
addition, quantal release in mocha cultures is more frequent and more sensitive
to sucrose. We conclude that lack of AP-3 results in more constitutive
secretion and loss of an asynchronous evoked release component, suggesting an
important function of AP-3 in regulating SV exocytosis at MF terminals
High frequency trans-splicing in a cell line producing spliced and polyadenylated RNA polymerase I transcripts from an rDNA-myc chimeric gene
The 2G1MycP2Tu1 cell line was obtained following transfection of human colon carcinoma cells from the SW613-S cell line with a plasmid carrying a genomic copy of the human MYC gene. 2G1MycP2Tu1 cells produce MYC mRNAs and proteins of abnormal size. In order to analyze the structure of these abnormal products, a cDNA library constructed using RNA isolated from these cells was screened with a MYC probe. Fifty clones were studied by DNA sequencing. The results indicated that a truncated copy of the MYC gene had integrated into an rDNA transcription unit in 2G1MycP2Tu1 cells. This was confirmed by northern blot analysis, PCR amplification on genomic DNA and fluorescent in situ hybridization (FISH) experiments on metaphase chromosomes. 2G1MycP2Tu1 cells produce hybrid rRNA-MYC RNA molecules that are polyadenylated and processed by splicing reactions involving natural and cryptic splice sites. These transcripts are synthesized by RNA polymerase I, as confirmed by actinomycin D sensitivity experiments, suggesting that 3′ end processing and splicing are uncoupled from transcription in this case. 2G1MycP2Tu1 cells also produce another type of chimeric mRNAs consisting of correctly spliced exons 2 and 3 of the MYC gene fused to one or more extraneous 5′ exons by proper splicing to the acceptor sites of MYC exon 2. These foreign exons belong to 33 different genes, which are located on 14 different chromosomes. These observations and the results of FISH and Southern blotting experiments lead us to conclude that trans-splicing events occur at high frequency in 2G1MycP2Tu1 cells
Alleviating Patch Overfitting with Automatic Test Generation: A Study of Feasibility and Effectiveness for the Nopol Repair System
International audienceAmong the many different kinds of program repair techniques, one widely studied family of techniques is called test suite based repair. However, test suites are in essence input-output specifications and are thus typically inadequate for completely specifying the expected behavior of the program under repair. Consequently, the patches generated by test suite based repair techniques can just overfit to the used test suite, and fail to generalize to other tests. We deeply analyze the overfitting problem in program repair and give a classification of this problem. This classification will help the community to better understand and design techniques to defeat the overfitting problem. We further propose and evaluate an approach called UnsatGuided, which aims to alleviate the overfitting problem for synthesis-based repair techniques with automatic test case generation. The approach uses additional automatically generated tests to strengthen the repair constraint used by synthesis-based repair techniques. We analyze the effectiveness of UnsatGuided: 1) analytically with respect to alleviating two different kinds of overfitting issues; 2) empirically based on an experiment over the 224 bugs of the Defects4J repository. The main result is that automatic test generation is effective in alleviating one kind of overfitting issue–regression introduction, but due to oracle problem, has minimal positive impact on alleviating the other kind of overfitting issue–incomplete fixing
Characterization of the livestock production system and potential for enhancing productivity through improved feeding in Amoni Division, Mweiga District, Central Kenya, May 2010
Lipid
droplets (LDs) are intracellular lipid-rich organelles that
regulate the storage of neutral lipids and were recently found to
be involved in many physiological processes, metabolic disorders,
and diseases including obesity, diabetes, and cancers. Herein we present
a family of new fluorogenic merocyanine fluorophores based on an indolenine
moiety and a dioxaborine barbiturate derivative. These so-called StatoMerocyanines
(SMCy) fluoresce from yellow to the near-infrared (NIR) in oil with
an impressive fluorescence enhancement compared to aqueous media.
Additionally, SMCy display remarkably high molar extinction coefficients
(up to 390 000 M<sup>–1</sup> cm<sup>–1</sup>) and high quantum yield values (up to 100%). All the members of
this new family specifically stain the LDs in live cells with very
low background noise. Unlike Nile Red, a well-known lipid droplet
marker, SMCy dyes possess narrow absorption and emission bands in
the visible, thus allowing multicolor imaging. SMCy proved to be compatible
with fixation and led to high-quality 3D images of lipid droplets
in cells and tissues. Their high brightness allowed efficient tissue
imaging of adipocytes and circulating LDs. Moreover their remarkably
high two-photon absorption cross-section, especially SMCy5.5 (up to
13 300 GM), as well as their capacity to efficiently fluoresce
in the NIR region led to two-photon multicolor tissue imaging (liver).
Taking advantage of the available color palette, lipid droplet exchange
between cells was tracked and imaged, thus demonstrating intercellular
communication
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