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951.
952.
The compensatory response is a regulatory event influencing the redundancy of the ribosomal RNA cistrons (rDNAs) of Drosophila melanogaster. In this report we attempt to demonstrate that the compensatory event and the thymidine analogue bromodeoxyuridine (BrdU) specifically interact. We conclude that the drug inhibits the compensatory response of Drosophila melanogaster XO males and argue that the compensatory event is not the passive consequence of replicational dominance known to occur in Drosophila polytene tissues. 相似文献
953.
M. P. Koshy G. Namkoong J. H. Roberds 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,97(5-6):990-993
Either by selective breeding for population divergence or by using natural population differences, F2 and advanced generation hybrids can be developed with high variances. We relate the size of the genetic variance to the population
divergence based on a forward and backward mutation model at a locus with two alleles with additive gene action. The effects
of population size and initial gene frequency are also explored. Larger parental population sizes increase the F2 genetic variance if the initial probability distribution is uniform or U-shaped. However, population size has the opposite
effect if the initial distribution of gene frequencies is skewed such as it would be with newly arriving alleles. These alleles
contribute to the genetic variance sooner when the selection pressure is higher or when the effective population size is smaller.
Received: 5 April 1998 / Accepted: 22 April 1998 相似文献
954.
Suzanne Bourgeois 《Journal of cellular biochemistry》1980,13(3):401-410
The glucocorticoid-induced lysis of lymphoid cell lines offers a genetic approach to steroid hormone action because unresponsive variants can easily be selected as resistant to this lytic effect. The present state of analysis of lymphocytolysis in two murine cell lines, the S49 T-lymphoma and the W7 thymoma, is reviewed. All glucocorticoid-resistant variants isolated so far result from various defects in the glucocorticoid receptor. The absence of variants blocked at another step of the lytic mechanism is discussed. The observed hemizygosity of the glucocorticoid receptor locus in the S49 line and the instability of cell hybrids illustrate some of the potential problems encountered in somatic cell genetics. 相似文献
955.
Markus Risch und Lars Andersen 《Journal of Ornithology》1998,139(2):173-177
Zusammenfassung Die als Unterarten klassifizierten europäischen Formen der Aaskrähe, Rabenkrähe und Nebelkrähe, besiedeln verschiedene, aneinandergrenzende Verbreitungsgebiete und hybridisieren in der Kontaktzone. Die Nachkommen von Mischpaaren sind fruchtbar und können sowohl mit anderen Hybriden als auch mit Raben- und Nebelkrähen erfolgreich brüten. Trotzdem kommt es zu keiner völligen Vermischung der Formen und/oder Verlagerung der Verbreitungsgebiete. Vor diesem Hintergrund untersuchten wir die Partnerwahl von Aaskrähen in der Hybridisierungszone auf der nordfriesischen Insel Amrum und stellten fest, daß Partner gleichen Phänotyps häufiger miteinander verpaart waren, als stochastisch zu erwarten gewesen wäre. Unsere Daten bestätigen vergleichbare Studien aus Hybridisierungszonen in Italien und Sibirien. Wir schließen daraus, daß phänotypisch selektive Partnerwahl bei der Aaskrähe ein allgemeines Phänomen sein könnte und diskutieren, warum dieses Verhalten anfitness-relevante Parameter gekoppelt sein sollte. Um welche es sich dabei handeln könnte, wurde bisher nicht hinreichend untersucht und muß deshalb offen bleiben.
Non-random mating of Crows (Corvus corone) in a hybrid zone of Carrion Crow (C. c. corone) and Hooded Crow (C. c. cornix)
Summary Carrion Crow and Hooded Crow are regarded as subspecies of the Crow. They show frequent hybridisation along the adjacent borders of their distribution. Mixed pairs produce fertile offspring which are able to breed successfully with both hybrids and mates of either phenotype. However, hybridisation does not lead to phenotypic changes of Carrion and Hooded Crows in general nor in their distinct distribution. We studied the mating behaviour of Crows in the hybrid zone on the Island of Amrum (Schleswig-Holstein, Germany) and found evidence that Crows may prefer mates of the same phenotype. Our data confirm previous studies which reported assortative mating with respect to plumage coloration from hybrid zones in Italy and Siberia. We discuss why this behaviour should be related tofitness traits which in our opinion have not yet been studied adequately nor identified.相似文献
956.
T E Broad D J Burkin L M Cambridge C Jones P E Lewis H G Morse D Geyer P D Pearce H A Ansari D W Maher 《Animal genetics》1995,26(2):85-90
Six loci, apoliproprotein B (including Ag(x) antigen), immunoglobulin kappa constant region (IGKC), luteinizing hormone/choriogonadotrophin receptor, avian myelocytomatosis viral related oncogene, neuroblastoma derived, ornithine decarboxylase, and proopiomelanocortin (adrenocorticotropin/beta-lipotropin) (POMC), were newly assigned to sheep chromosome 3p using a chromosomally characterized minipanel of sheep-hamster cell hybrids. Isotopic in situ hybridization of IGKC to sheep chromosome 3p22–p17 is reported, confirming the cell hybrid assignment. As these loci are all known to map to human chromosome 2p, this study demonstrates that this chromosomal segment is extensively conserved in sheep. Only POMC has been previously assigned to cattle chromosome 11, which is the equivalent of sheep chromosome 3p. Therefore, we predict that the other loci assigned in this study to sheep 3p are likely to be located on cattle 11. The provisional assignment of an additional locus, annexin-like to sheep chromosome 3p is also reported. 相似文献
957.
Tzintli Meraz‐Medina Benjamín Nogueda‐Torres Ren Salvador Ceballos‐Rodríguez Karla Cytlalli Godínez‐Aceves Jos Alejandro Martínez‐Ibarra 《Journal of vector ecology》2019,44(1):173-178
Chagas disease is one of the main vector‐borne diseases in Latin America, including Mexico. Understanding the biological parameters of the triatomine species is a crucial first step in estimating the epidemiologic importance of each group. The aim of this study was to compare the biological fitness of Meccus pallidipennis (Stål), M. bassolsae (Alejandre, Nogueda, Cortez, Jurberg, Galvão, Carcavallo) (Hemiptera: Reduviidae: Triatominae) and their laboratory hybrids, by estimating six biological parameters in order to increase the knowledge of the potential role of triatomine hybrids in the transmission of Trypanosoma cruzi to reservoir hosts. Biological parameters related to lifespan, number of blood meals to molt, mortality for each instar, percentage of females at the end of the cycle, number of eggs laid, and hatching of eggs in four cohorts of 100 specimens of M. pallidipennis, M. bassolsae, and their laboratory hybrids were evaluated and compared. In four of the six studied parameters (accumulative mortality, the percentage of females, mean number of laid eggs, and egg hatching), the hybrid cohorts had better fitness results than the parental cohorts. The increase in hybrid fitness found in our study could lead to an increase in the epidemiologic risks caused by transmission of T. cruzi to humans. 相似文献
958.
Fen Liu Mei-Hong Chen Yan-Xia Hu Qiong Zhan Jin-Yan Zhang Zi-Yue Zhang Si-Si Wang Wen-Cai Ye Lei Wang 《化学与生物多样性》2023,20(4):e202300234
Six new phloroglucinol derivatives, xanchryones I−N ( 1 – 6 ), were isolated from the leaves of Xanthostemon chrysanthus. Compounds 1 – 6 are unusual phloroglucinol-amino acid hybrids constructed through C2−N and O−C1′ bonds forming a peculiar oxazole ring. The structures and absolute configurations of compounds 1 – 6 were determined by MS, NMR, and single-crystal X-ray diffraction. Moreover, the anti-inflammatory and antibacterial activities of these compounds were evaluated. 相似文献
959.
Danny Awty-Carroll Elena Magenau Mohamad Al Hassan Enrico Martani Mislav Kontek Philip van der Pluijm Chris Ashman Emmanuel de Maupeou Jon McCalmont Gert-Jan Petrie Chris Davey Kasper van der Cruijsen Vanja Jurišić Stefano Amaducci Isabelle Lamy Anita Shepherd Jason Kam Annick Hoogendam Michele Croci Oene Dolstra Andrea Ferrarini Iris Lewandowski Luisa M. Trindade Andreas Kiesel John Clifton-Brown 《Global Change Biology Bioenergy》2023,15(4):399-423
Miscanthus, a C4 perennial rhizomatous grass from Asia is a leading candidate for the supply of sustainable biomass needed to grow the bioeconomy. European Miscanthus breeding programmes have recently produced a new range of seeded hybrids with the objective of increasing scalability to large acreages limited by current clonal propagation. For the EU-GRACE project, new replicated field trials were established in seven locations across Europe in 2018 with eight intraspecific M. sinensis hybrids (sin × sin) and six M. sacchariflorus × M. sinensis (sac × sin) from Dutch and UK breeding programmes, respectively, with clonal Miscanthus × giganteus. The planting density of the sin × sin was double that of sac × sin (30,000 & 15,000 plants ha−1), creating commercially relevant upscaling comparisons between systems. Over the first 3 years, the establishment depended on location and hybrid. The mature sin × sin hybrids formed tight tufts of shoots up to 2.5 m tall which flower and senesce earlier than the taller sac × sin hybrids. Following the third growing season, the highest yields were recorded in Northern Italy at a low altitude (average 13.7 (max 21) Mg DM ha−1) and the lowest yielding was on the industrially damaged marginal land site in Northern France (average 7.0 (max 10) Mg DM ha−1). Moisture contents at spring harvest were lowest in Croatia (21.7%) and highest in Wales, UK (41.6%). Overall, lower moisture contents at harvest, which are highly desirable for transport, storage and for most end-use applications, were found in sin × sin hybrids than sac × sin (30% and 40%, respectively). Yield depended on climate interactions with the hybrid and their associated planting systems. The sin × sin hybrids appeared better adapted to northern Europe and sac × sin hybrids to southern Europe. Longer-term yield observations over crop lifespans will be needed to explore the biological (yield persistence) and economic costs and benefits of the different hybrid systems. 相似文献
960.
《Fungal biology》2022,126(3):250-266
Many species in the Fusarium fujikuroi Species Complex (FFSC) have an affinity for grass species, with whom they live in an endophytic association or cause disease. We recovered isolates of Fusarium from agriculturally important grasses in Africa and Brazil, and characterized them with morphological markers, mating type, and Amplified Fragment Length Polymorphisms (AFLPs). We also conducted multi-locus phylogenetic analyses based on partial DNA sequences of translation elongation factor-1α (TEF1), β-tubulin (TUB), and the second largest subunit of RNA polymerase (RPB2) gene regions. Sexual cross fertility was used to test the biological species concept and the sexual stage of F. madaense is described. A novel species within the FFSC, Fusarium mirum, that is different from the other known species in the complex, was formally described. Fusarium mirum, F. madaense, and Fusarium andiyazi are a tightly intertwined species trio that are morphologically identical, but phylogenetically distinguishable, and amongst whom interspecific genetic exchange may still occur. These three species are so close that they cannot be reliably distinguished if only sequences of the TEF1 gene are used. In pathogenicity tests, all tested isolates of F. madaense from sugarcane, sorghum, maize, millet and Brachiaria could induce stalk rot in sorghum, maize and millet, and pokkah boeng in sugarcane. This study increases our understanding of the diversity of species within the FFSC that cause disease in tropical grasses or act as endophytes, and their geographic distributions. The genetically close relationship between F. mirum, F. madaense, and F. andiyazi provides an opportunity to study and identify factors underlying their limited inter-specific cross-fertility and sympatric speciation. 相似文献