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1.
A new class of Phycomyces behavioral mutants with enhanced tropic responses has been analyzed genetically to determine the number of genes involved and the nature of their expression. These hypertropic mutants carry pleiotropic nuclear mutations. Besides their effects on sensory behavior, they also affect morphology and meiotic processes. Behavioral analyses of heterokaryons containing hypertropic and wild-type nuclei in varying proportions show that the hypertropic mutations in strains L82, L84, L86, and L88 are strongly dominant. Conversely, the hypertropic mutations carried by the strains L83, L85, and L87 are strongly recessive. We performed recombination analyses between hypertropic mutants and mutants with diminished phototropism, affected in the seven genes madA to madG. We found no evidence of linkage between the hypertropic mutations and any of these mad mutations. From crosses, we isolated double mutants carrying hypertropic mutations together with madC (night blind) and madG (stiff) mutations. The behavioral phenotypes of the double mutants are intermediate between those of the parentals. Complementation analyses show that the three recessive hypertropic mutations affect the same gene, which we call madH. The expression of the recessive hypertropic allele becomes dominant in heterokaryons carrying madC and madH nuclei; the madC gene has been implicated separately with the photoreceptor at the input to the sensory pathway, while the madH gene is associated with the growth control output. This result suggests the physical interaction of both gene products, madH and madC, in a molecular complex for the photosensory transduction chain. 相似文献
2.
C. PRADO E CASTRO A. SERRANO P. MARTINS DA SILVA M. D. GARCÍA 《Medical and veterinary entomology》2012,26(4):417-431
Information on Diptera community, seasonality and successional patterns in every geographical region is fundamental for the use of flies as forensic indicators of time of death. In order to obtain these data from the Lisbon area (Portugal), experiments were conducted during the four seasons of the year, using piglet carcasses as animal models. Five stages were recognized during the decomposition process. The stages, besides visually defined, could be separated taking into account the occurrence and abundance of the specific groups of Diptera collected. In general, the bloated stage recorded higher abundance and species‐richness values. Seventy‐one species were identified, belonging to 39 families, in a total of 20 144 adult Diptera collected. Autumn yielded the highest values of species richness, whereas winter had the lowest. In all seasons of the year, Calliphoridae was the dominant family; Muscidae and Fanniidae were very abundant as well. Calliphora vicina Robineau‐Desvoidy, Calliphora vomitoria (Linnaeus), Chrysomya albiceps (Wiedemann), Lucilia ampullacea Villeneuve, Lucilia caesar (Linnaeus), Lucilia sericata (Meigen) (Calliphoridae), Hydrotaea ignava (Harris), Muscina prolapsa (Harris), Synthesiomyia nudiseta (van der Wulp) (Muscidae), Piophila megastigmata McAlpine, Stearibia nigriceps (Meigen) (Piophilidae) and Nemopoda nitidula (Fallén) (Sepsidae) were revealed to be very important members of the Diptera community collected. The necrophagous behaviour, demonstrated by their immatures, using carrion as a food source makes them useful forensic indicator species. Also of relevance is the presence of Chrysomya megacephala (Fabricius), S. nudiseta and P. megastigmata, foreign species established in the local carrion communities. This study also marks the first record of S. nudiseta in Portugal. 相似文献
3.
The acrosome of the spermatozoa is the organelle involved in its penetration through the ova membranes during the fertilization process. Several features of this process are considered to be related to the fertilization events e.g. some substance coats outside the membrane. During the maturation process the spermatozoa of Conocephalus saltator develop a coat of tubules and filaments which overly some membrane regions in a specific array. The mature spermatozoa are seen to adhere in these regions and form threads of 20 cells long and five to six wide. It is suggested that the external coat plays a role in this 'sticking' phenomenon. 相似文献
4.
该实验以烟草悬浮细胞 BY 2 为材料,在烟草悬浮细胞中分别加入0.05、0.10、0.15、0.20 mmol·L-1AlCl3,以等体积去离子水处理的悬浮细胞液为对照,并依据前述实验结果选择0.15 mmol·L-1 AlCl3,分别添加5 mmol·L-1 DMTU(H2O2 抑制剂)、20 μmol·L-1CaCl2、15 μmol·L-1 LaCl3(Ca2+通道抑制剂)和50 μmol·L-1 ATP设计多项处理,分析胞外ATP(eATP)对铝离子(Al3+)胁迫引起的植物细胞死亡及其胞内H2O2、Ca2+的影响,以揭示Al3+胁迫下植物调节细胞死亡的可能机制,进一步扩展对eATP功能的认知。结果显示:(1)随着 AlCl3 胁迫浓度的提高,细胞死亡水平和胞内H2O2水平上升,而胞内Ca2+和eATP水平则逐渐降低。(2)外援施加H2O2抑制剂 DMTU(二甲基硫脲)和Ca2+能够有效缓解AlCl3诱导的细胞死亡水平的上升;而Ca2+通道抑制剂LaCl3(三氯化镧)则加剧了AlCl3胁迫下的细胞死亡。(3)在AlCl3胁迫下对细胞添加外源ATP,能够缓解AlCl3胁迫下胞内H2O2水平上升和Ca2+水平下降的同时,并显著降低AlCl3胁迫导致的细胞死亡。研究表明, Al3+以剂量依赖的模式提升细胞死亡和细胞内H2O2的水平并降低胞内Ca2+和eATP水平,AlCl3诱导的细胞死亡受到H2O2和Ca2+水平变化的调节,eATP可以通过调节H2O2与Ca2+水平缓解AlCl3诱导的细胞死亡。推测Al3+胁迫可能通过抑制钙离子通道而破坏了细胞内H2O2和Ca2+之间的协同关系,外源ATP对Al3+诱导H2O2上升的缓解作用可能是由于其提升了细胞的抗氧化能力。 相似文献
5.
Mark Lipson Po-Ru Loh Sriram Sankararaman Nick Patterson Bonnie Berger David Reich 《PLoS genetics》2015,11(11)
The human mutation rate is an essential parameter for studying the evolution of our species, interpreting present-day genetic variation, and understanding the incidence of genetic disease. Nevertheless, our current estimates of the rate are uncertain. Most notably, recent approaches based on counting de novo mutations in family pedigrees have yielded significantly smaller values than classical methods based on sequence divergence. Here, we propose a new method that uses the fine-scale human recombination map to calibrate the rate of accumulation of mutations. By comparing local heterozygosity levels in diploid genomes to the genetic distance scale over which these levels change, we are able to estimate a long-term mutation rate averaged over hundreds or thousands of generations. We infer a rate of 1.61 ± 0.13 × 10−8 mutations per base per generation, which falls in between phylogenetic and pedigree-based estimates, and we suggest possible mechanisms to reconcile our estimate with previous studies. Our results support intermediate-age divergences among human populations and between humans and other great apes. 相似文献
6.
MORAIS PAULO AMORIM ANTÓNIO VIEIRA DA SILVA CLÁUDIA RIBEIRO TERESA COSTA SANTOS JORGE AFONSO COSTA HELOÍSA 《Journal of genetics》2015,94(3):509-512
Journal of Genetics - 相似文献
7.
E D Lipson 《Biophysical journal》1975,15(10):1033-1045
Wiener kernels have been measured for the light growth response of a number of mutants of Phycomyces which show abnormal phototropism (mad mutants). Representative mutants were chosen from the six complementation groups (madA to madF) associated with the light response pathway. One group, madA, associated with the input part of the pathway, exhibits an essentially normal response provided it is tested above its moderate threshold. The groups madB and madC appear more defective, in that their kernel amplitudes are very small even above their thresholds. Their similarity to each other suggests a close functional connection between the respective genes. The remaining three groups (madD, madE, and madF) have all been associated with the output of the pathway. Tbe kernels for all three indicate a gain reduction, which depends gradually on intensity. These three groups appear to have the same absolute threshold as wild-type. None of the mutants studied shows special behavior at high intensity that could be evidence of alterations in the photoreceptor complex. 相似文献
8.
9.
MÁRCIA FERNANDES DE AQUINO SANTOS JOSÉ RICARDO M. MERMUDES VERA MARIA MEDINA DA FONSECA 《Palaeontology》2011,54(4):807-814
Abstract: A specimen of Curculionidae (Curculioninae) is described as Arariperhinus monnei gen. et sp. nov. The specimen is preserved on a laminated limestone sample of the Crato Formation (Santana Group), Lower Cretaceous (Aptian–Albian), and was collected from a quarry near Nova Olinda, Chapada do Araripe, State of Ceará, Brazil. The genus is placed in the subfamily Curculioninae because of its strongly convex body and relatively slender rostrum, but mainly by its rounded eyes and lack of a prosternal sulcus and tibial spurs. The very prominent eyes in lateral view, a cylindrical rostrum and a straight posterior margin of ventrite II are strong indications that this fossil belongs to the tribe Anthonomini. However, the claws, which would resolve the exact placement of this fossil, are poorly preserved. Arariperhinus monnei gen. et sp. nov. is distinguishable by the combination of several characters and the first record of the family Curculionidae in the Santana Group; it is the oldest record of a member of the subfamily Curculioninae. 相似文献
10.