Search results for "Dros"
showing 10 items of 1330 documents
Augļu mušas Drosophila melanogaster tēviņu agresīvās uzvedības saistība ar rauga daudzumu barībā
2022
Agresija ir svarīgs evolūcijas virzītājspēks. Dzīvnieki, kuri būs spējīgāki uzvarēt konfliktus varēs ar lielāku varbūtību nodot savus gēnus nākošajām paaudzēm. Tomēr kādi faktori ietekmē dzīvnieka varbūtību uzvarēt nav līdz galam noskaidrots. Teorētiskie modeļi un esošie pētījumi sniedz tikai virspusēju skatījumu. Dzīvnieki savas dzīves laikā būs pakļauti dažādiem vides faktoriem ar variējošu pakāpi, tomēr, ne visi būs vienlīdz nozīmīgi agresīvas uzvedības mainībā. Uzturs dzīvniekiem mainās dzīves laikā un attīstības sākumā optimālā barības vielu attiecība būs svarīga indivīda nākotnes izdzīvošanā un ģenētiskajā fitnesā, jo fiziskais fenotips visam mūžam veidojas tieši individuālās attīstīb…
InBO3 and ScBO3 at high pressures: an ab initio study of elastic and thermodynamic properties
2016
We have theoretically investigated the elastic properties of calcite-type orthoborates ABO(3) (A= Sc and In) at high pressure by means of ab initio total-energy calculations. From the elastic stiffness coefficients, we have obtained the elastic moduli (B, G and E), Poisson's ratio (nu), B/G ratio, universal elastic anisotropy index (A(U)), Vickers hardness, and sound wave velocities for both orthoborates. Our simulations show that both borates are more resistive to volume compression than to shear deformation (B > G). Both compounds are ductile and become more ductile, with an increasing elastic anisotropy, as pressure increases. We have also calculated some thermodynamic properties, like D…
Prebiotic Evolution and the Origin of Life: Chemical and Biochemical Aspects
1988
Evolution, as the term is used here, signifies any development or change adapting to the environment. Chemical evolution connotes changes of chemical substances, it thus signifies that changes occur fundamentally in the molecules. Frequently “chemical evolution” is used synonymously for “abiotic” or “prebiotic formation” of organic molecules in a cosmic system, usually on the prebiotic (or primitive) Earth. It is then assumed that the organic molecules were formed from the constituents of the primitive atmosphere, hydrosphere, and — in part — lithospere.
Spectroscopic and quantum chemical study of pressure effects on solvated chlorophyll
2004
Abstract Hydrostatic pressure effects up to 907 MPa on absorption spectra of chlorophyll a molecules dissolved in diethyl ether have been studied at ambient temperature both experimentally and theoretically using quantum chemistry methods. The fluorescence spectra are studied only experimentally. The data suggest that coordination interactions between the central Mg atom of the chlorophyll and solvent molecules along with interactions that modify the porphyrin skeleton of the solute are responsible for the observed differences of pressure dependence of the Q y , Q x , and Soret spectral bands. The coordination number of the Mg atom changes from five to six between 400 and 600 MPa.
Genome-wide characterization of chromatin binding and nucleosome spacing activity of the nucleosome remodelling ATPase ISWI.
2010
The evolutionarily conserved ATP-dependent nucleosome remodelling factor ISWI can space nucleosomes affecting a variety of nuclear processes. In Drosophila, loss of ISWI leads to global transcriptional defects and to dramatic alterations in higher-order chromatin structure, especially on the male X chromosome. In order to understand if chromatin condensation and gene expression defects, observed in ISWI mutants, are directly correlated with ISWI nucleosome spacing activity, we conducted a genome-wide survey of ISWI binding and nucleosome positioning in wild-type and ISWI mutant chromatin. Our analysis revealed that ISWI binds both genic and intergenic regions. Remarkably, we found that ISWI…
The 18S ribosomal RNA m 6 A methyltransferase Mettl5 is required for normal walking behavior in Drosophila
2020
RNA modifications have recently emerged as an important layer of gene regulation. N6-methyladenosine (m6A) is the most prominent modification on eukaryotic messenger RNA and has also been found on noncoding RNA, including ribosomal and small nuclear RNA. Recently, several m6A methyltransferases were identified, uncovering the specificity of m6A deposition by structurally distinct enzymes. In order to discover additional m6A enzymes, we performed an RNAi screen to deplete annotated orthologs of human methyltransferase-like proteins (METTLs) in Drosophila cells and identified CG9666, the ortholog of human METTL5. We show that CG9666 is required for specific deposition of m6A on 18S ribosomal …
NOseq: amplicon sequencing evaluation method for RNA m6A sites after chemical deamination
2020
Abstract Methods for the detection of m6A by RNA-Seq technologies are increasingly sought after. We here present NOseq, a method to detect m6A residues in defined amplicons by virtue of their resistance to chemical deamination, effected by nitrous acid. Partial deamination in NOseq affects all exocyclic amino groups present in nucleobases and thus also changes sequence information. The method uses a mapping algorithm specifically adapted to the sequence degeneration caused by deamination events. Thus, m6A sites with partial modification levels of ∼50% were detected in defined amplicons, and this threshold can be lowered to ∼10% by combination with m6A immunoprecipitation. NOseq faithfully d…
Twelve-Month Estrogen Levels in Premenopausal Women With Hormone Receptor–Positive Breast Cancer Receiving Adjuvant Triptorelin Plus Exemestane or Ta…
2016
Purpose To describe estradiol (E2), estrone (E1), and estrone sulfate (E1S) levels during the first year of monthly triptorelin plus exemestane or tamoxifen and to assess possible suboptimal suppression while receiving exemestane plus triptorelin. Patients and Methods Premenopausal patients with early breast cancer on the Suppression of Ovarian Function Trial who selected triptorelin as the ovarian suppression method and were randomly assigned to exemestane plus triptorelin or tamoxifen plus triptorelin were enrolled until the target population of 120 patients was reached. Blood sampling time points were 0, 3, 6, 12, 18, 24, 36, and 48 months. Serum estrogens were measured with a highly sen…
Time-dependent changes in serum 3α-androstanediol glucuronide correlate with hirsutism scores after ovarian suppression
1995
The clinical utility of serum 3 alpha-androstanediol glucuronide level has been controversial. Among the concerns regarding its lack of utility has been the finding that suppression of serum 3 alpha-androstanediol glucuronide does not occur readily with treatment. We hypothesized that because the treatment of hirsutism requires a prolonged duration, a longer observation period is required for changes in serum 3 alpha-androstanediol glucuronide to be measured. Therefore, we studied the clinical and hormonal changes in 11 women treated for hirsutism with a gonadotropin-releasing hormone agonist (GnRH-a) for 1 year. A progressive reduction in Ferriman-Gallwey scores occurred, which was signifi…
Increased anti-Mullerian hormone levels and ovarian size in a subgroup of women with functional hypothalamic amenorrhea: further identification of th…
2016
Functional hypothalamic amenorrhea is a disorder characterized by cessation of menstrual cycles in the absence of organic disease. In most patients, it occurs in adult life after a stressful event and may be related to a condition of mild chronic energy deprivation. The endocrine pattern is characterized by low estrogen levels with an absent response to a progestogen challenge test and low-normal gonadotropin levels. A few studies have shown that some of these women may have some features of polycystic ovary syndrome; these features include an increased androgen response to gonadotropins, increased anti-Mullerian hormone levels, and altered ovarian morphology or increased ovarian size. Thes…