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1.
The process of cell fusion is a basic developmental feature found in most eukaryotic organisms. In filamentous fungi, cell fusion events play an important role during both vegetative growth and sexual reproduction. We employ the model organism Neurospora crassa to dissect the mechanisms of cell fusion and cell-cell communication involved in fusion processes. In this study, we characterized a mutant with a mutation in the gene so, which exhibits defects in cell fusion. The so mutant has a pleiotropic phenotype, including shortened aerial hyphae, an altered conidiation pattern, and female sterility. Using light microscopy and heterokaryon tests, the so mutant was shown to possess defects in germling and hyphal fusion. Although so produces conidial anastomosis tubes, so germlings did not home toward wild-type germlings nor were wild-type germlings attracted to so germlings. We employed a trichogyne attraction and fusion assay to determine whether the female sterility of the so mutant is caused by impaired communication or fusion failure between mating partners. so showed no defects in attraction or fusion between mating partners, indicating that so is specific for vegetative hyphal fusion and/or associated communication events. The so gene encodes a protein of unknown function, but which contains a WW domain; WW domains are predicted to be involved in protein-protein interactions. Database searches showed that so was conserved in the genomes of filamentous ascomycete fungi but was absent in ascomycete yeast and basidiomycete species.  相似文献   

2.
Drosophila eye development is under the control of early eye specifying genes including eyeless (ey), twin of eyeless (toy), eyes absent (eya), dachshund (dac) and sine oculis (so). They are all conserved between vertebrates and insects and they interact in a combinatorial and hierarchical network to regulate each other expression. so has been shown to be directly regulated by ey through an eye-specific enhancer (so10). We further studied the regulation of this element and found that both Drosophila Pax6 proteins namely EY and TOY bind and positively regulate so10 expression through different binding sites. By targeted mutagenesis experiments, we disrupted these EY and TOY binding sites and studied their functional involvement in the so10 enhancer expression in the eye progenitor cells. We show a differential requirement for the EY and TOY binding sites in activating so10 during the different stages of eye development. Additionally, in a rescue experiment performed in the so(1) mutant, we show that the EY and TOY binding sites are required for compound eye and ocellus development respectively. Altogether, these results suggest a differential requirement for EY and TOY to specify the development of the two types of adult visual systems, namely the compound eye and the ocellus.  相似文献   

3.
ABSTRACT. Sugar-free egg albumin solution was 'force fed' to female C.pipiens pallens Coquillett, by first stimulating their labella briefly with 1.0 M sucrose, so that they then took the protein meal into the crop. This protein-food was nevertheless easily eliminated by the females, totally undigested, so that it failed to activate oogenesis, just as sugared albumin fails to do so also.  相似文献   

4.
The neuropeptide pigment-dispersing factor (PDF) is a key transmitter in the circadian clock of Drosophila melanogaster. Here we studied the rhythmic behavior of neural mutants with modified arborizations of the large PDF neurons. In sine oculis(1) (so(1)) mutants we found a higher density of PDF fibers in the fly's pacemaker center, the accessory medulla. These flies exhibited a significantly longer period (24.6 h) than control flies. When PDF levels were elevated to very high levels in the dorsal brain as true for so(mda) mutants and small optic lobes;so(1) double mutants (sol(1);so( 1)), a short-period component split off the long period in behavioral rhythmicity. The short period became shorter the higher the amount of PDF in this brain region and reached a value of approximately 21 h. The period alterations were clearly dependent on PDF, because so(1);Pdf 01 and so(mda);Pdf 01 double mutants showed a single free-running component with a period similar to Pdf 01 mutants (approximately 22.5 h) and significantly longer than the short period of so(mda) mutants. These observations indicate that PDF feeds back on the clock neurons and changes their period. Obviously, PDF lengthens the period of some clock neurons and shortens that of others.  相似文献   

5.
ABSTRACT. The locomotor activity patterns of wildtype Drosophila melanogaster and the mutants so (sine oculis) and sol (small optic lobes) were investigated. In all strains the proportions showing circadian rhythmicity, arrhythmicity and more complex patterns which could not be thus classified were similar. The occurrence of abnormal activity patterns is thus not a property of the mutation as previously claimed (Mack & Engelmann, 1981). In flies with a distinct circadian rhythmicity, the period lengths (τ) varied between strains, τ for wildtype Italy and the mutant so was longer than for wildtype Berlin and the mutant sol. As different τ's have been reported by others, τ does not seem to be closely determined for Drosophila melanogaster. Many flies exhibited two rhythms simultaneously, one with τ shorter and one with τ longer than 24 h, apparently implying two-oscillator control of the locomotor activity. The eyeless so mutants were entrained by LD cycles, so the compound eyes are not necessary, and so must possess the relevant photoreceptor(s) elsewhere. This may therefore also be true for the wildtype. Histology of the so adults revealed no correlation between the degree of reduction in the medulla and the occurrence of abnormal activity patterns. Since the only structures common to the medulla of so and sol are known to be large tangential cells, it is concluded that either they are of importance for the rhythmic system, or the oscillator(s) controlling locomotor activity is (are) not located in the medulla.  相似文献   

6.
1. Catecholamines can nearly double (Na+ + K+)-ATPase acts effect is not mediated by cyclic AMP and is not beta-adrenergic. 3. Orthodihydroxybenzene compounds and their orthoquinone derivatives enhance (Na+ + K+)-ATPase activity. 4. Enhancement of (Na+ + K+)-ATPase activity by catechols is not due to increased availability of ATP. 5. It is suggested that catechols and their orthoquinones somehow alter or protect the configuration of the enzyme so that it becomes more active or so protect the configuration of the enzyme so that it becomes more active or so that its activity is maintained under conditions in which its activity is otherwise diminished.  相似文献   

7.
Anne Fadiman's The Spirit Catches You and You Fall Down: A Hmong Child, Her American Doctors, and the Collision of Two Cultures (Noonday Press, 1997) is widely used in "cultural competence" efforts within U.S. medical school curricula. This article addresses the relationship between theory, narrative form, and teaching through a close critical reading of that book that is informed by theories of tragedy and ethnographies of medicine. I argue that The Spirit Catches You is so influential as ethnography because it is so moving as a story; it is so moving as a story because it works so well as tragedy; and it works so well as tragedy precisely because of the static, reified, essentialist understanding of "culture" from which it proceeds. If professional anthropologists wish our own best work to speak to "apparitions of culture" within medicine and other "cultures of no culture," I suggest that we must find compelling new narrative forms in which to convey more complex understandings of "culture."  相似文献   

8.
M. A. Serikaku  J. E. O''Tousa 《Genetics》1994,138(4):1137-1150
The so(mda) (sine oculis-medusa) mutant is the result of a P element insertion at position 43C on the second chromosome. so(mda) causes aberrant development of the larval photoreceptor (Bolwig's) organ and the optic lobe primordium in the embryo. Later in development, adult photoreceptors fail to project axons into the optic ganglion. Consequently optic lobe development is aborted and photoreceptor cells show age-dependent retinal degeneration. The so gene was isolated and characterized. The gene encodes a homeodomain protein expressed in the optic lobe primordium and Bolwig's organ of embryos, in the developing adult visual system of larvae, and in photoreceptor cells and optic lobes of adults. In addition, the SO product is found at invagination sites during embryonic development: at the stomadeal invagination, the cephalic furrow, and at segmental boundaries. The mutant so(mda) allele causes severe reduction of SO embryonic expression but maintains adult visual system expression. Ubiquitous expression of the SO gene product in 4-8-hr embryos rescues all so(mda) mutant abnormalities, including the adult phenotypes. Thus, all deficits in adult visual system development and function result from failure to properly express the so gene during embryonic development. This analysis shows that the homeodomain containing SO gene product is involved in the specification of the larval and adult visual system development during embryogenesis.  相似文献   

9.
A relaxation of previous recommendations on the numbering of the atoms of myo-inositol is suggested, so that substituents are not necessarily numbered so that the smallest possible locant is used. This allows an alternative designation to be used, when authors wish, to bring out structural relationships.  相似文献   

10.
大别山区中药材资源的开发和利用对策   总被引:2,自引:0,他引:2  
安徽省大别山区有中药材品种近1800余种,是天然的药材宣言加。合理的开发利用当地丰富的中药材资源,对于脱贫致富、提高健康水平有重要意义。  相似文献   

11.
In Drosophila, the sine oculis (so) gene is important for the development of the entire visual system, including Bolwig's organ, compound eyes and ocelli. Together with twin of eyeless, eyeless, eyes absent and dachshund, so belongs to a network of genes that by complex interactions initiate eye development. Although much is known about the genetic interactions of the genes belonging to this retinal determination network, only a few such regulatory interactions have been analysed down to the level of DNA-protein interactions. Previous work in our laboratory identified an eye/ocellus specific enhancer of the sine oculis gene that is directly regulated by eyeless and twin of eyeless. We further characterized this regulatory element and identified a minimal enhancer fragment of so that sets up an autoregulatory feedback loop crucial for proper ocelli development. By systematic analysis of the DNA-binding specificity of so we identified the most important nucleotides for this interaction. Using the emerging consensus sequence for SO-DNA binding we performed a genome-wide search and have thereby been able to identify eyeless as well as the signalling gene hedgehog as putative targets of so. Our results strengthen the general assumption that feedback loops among the genes of the retinal determination network are crucial for proper development of eyes and ocelli.  相似文献   

12.
Seven strains of nonproteolytic Clostridium botulinum (types B, E, and F) were each inoculated into a range of anaerobic cooked puréed vegetables. After incubation at 10 degrees C for 15 to 60 days, all seven strains formed toxin in mushrooms, five did so in broccoli, four did so in cauliflower, three did so in asparagus, and one did so in kale. Growth kinetics of nonproteolytic C. botulinum type B in cooked mushrooms, cauliflower, and potatoes were determined at 16, 10, 8, and 5 degrees C. Growth and toxin production occurred in cooked cauliflower and mushrooms at all temperatures and in potatoes at 16 and 8 degrees C. The C. botulinum neurotoxin was detected within 3 to 5 days at 16 degrees C, 11 to 13 days at 10 degrees C, 10 to 34 days at 8 degrees C, and 17 to 20 days at 5 degrees C.  相似文献   

13.
The recognition that we are in the distinct new epoch of the Anthropocene suggests the necessity for ecological restoration to play a substantial role in repairing the Earth's damaged ecosystems. Moreover, the precious yet limited resources devoted to restoration need to be used wisely. To do so, we call for the ecological restoration community to embrace the concept of evidence‐based restoration. Evidence‐based restoration involves the use of rigorous, repeatable, and transparent methods (i.e. systematic reviews) to identify and amass relevant knowledge sources, critically evaluate the science, and synthesize the credible science to yield robust policy and/or management advice needed to restore the Earth's ecosystems. There are now several examples of restoration‐relevant systematic reviews that have identified instances where restoration is entirely ineffective. Systematic reviews also serve as a tool to identify the knowledge gaps and the type of science needed (e.g. repeatable, appropriate replication, use of controls) to improve the evidence base. The restoration community, including both scientists and practitioners, needs to make evidence‐based restoration a reality so that we can move from best intentions and acting with so‐called “purpose” to acting for meaningful impact. Doing so has the potential to serve as a rallying point for reframing the Anthropocene as a so‐called “good” epoch.  相似文献   

14.
Contrary to Mealey's view, it is shown that offspring can be more similar to one parent than to another. Focusing on genes identical by descent can obscure a more general principle. If a gene can ensure its own survival by acting so as to bring about the reproduction of family members with whom it shares copies, then it should also be able to do so by benefiting any organism in which copies of itself are to be detected. If so, an explanation is provided for assortative mating, within-family favoritism, selective friendship, and ethnocentrism. Discussion is provided of how genetic similarity detection may occur.  相似文献   

15.
Breaking glass?     
Why are women so under-represented at the top echelons of science? Why do so many drop out just as their careers should be blossoming? Are women in science being actively discriminated against by their peers, and, if, so what can be done about this? These were just a few of the puzzles reflected upon at a recent European meeting that examined the role of women in science. Thankfully, there is evidence that, today, there is real opportunity, as well as mere light, emerging through the ceiling that caps so many careers.  相似文献   

16.
17.
Genetic dissection of the anterior optic tract of Drosophila melanogaster   总被引:1,自引:0,他引:1  
Electron microscopy shows that in wild-type Drosophila melanogaster the anterior optic tract (AOT) is formed by about 1260 fibers in males and slightly fewer in females. Golgi staining suggests that most AOT fibers connect the lobula with different regions of the central brain. In the sine oculis (so) and small optic lobes (sol) mutants the number of axons is drastically reduced, by 58% in sol and by 35% in so. In the double mutant sol:so there is a loss of up to 83% of the fibers in the AOT. Approximately half of the remaining 220 fibers form a well defined subbundle of very thin axons which is identifiable in wild type as well as in both single mutants. The fibers of this subbundle neither originate nor terminate in the visual ganglia: instead, they connect two different central brain regions. It is concluded that the combined action of the sol and so mutations abolishes more than 90% of the fibers of visual origin or destination in the AOT. Quantitative analysis of electron micrographs shows that the so and sol mutations act independently on nearly exclusive subsets of axons in the AOT.  相似文献   

18.
北京地区油松胚珠发育时期的确定   总被引:1,自引:0,他引:1  
采用显微观察法对北京地区不同发育时期的油松胚珠进行解剖结构观察,以确定北京地区油松胚珠的发育时期。结果表明,北京地区油松胚珠的发育历时13个月(从2003年4月~2004年5月),具体时期为:2003年4月12日为胚珠分化期,4月21日左右为大孢子母细胞时期,5月至8月为游离核时期,2003年8月至2004年2月为胚珠休眠期,2004年4月15日左右进入雌配子体细胞化时期,4月21日左右为颈卵器原始细胞活动期,5月8日左右为中央细胞分裂期,5月14日左右为成熟颈卵器时期。本研究结果中油松胚珠经历的发育阶段与前人的研究基本一致,但在时间上存在差异,而且北京地区比辽宁兴城地区油松胚珠发育时期平均提前了大约20~30 d。  相似文献   

19.
The purpose of this paper is to examine how speech styles are elaborated for presenting individual personality. Through the narratives of ten selected interviewees, some social norms internalised by them emerged. Age, status and career are associated to the joo/ge (upper/lower) and the senpai/koohai (senior/junior) relationships. Whether it is the first meeting and the length of relationship are associated to shin/so (intimacy/distance) and uchi/soto (in-group/out-group). In particular the notion of shin/so takes a role for adjusting speech styles. According to the narratives of individual episodes, there are several factors of determination of speech style, which are not necessarily following social norms. The way of constructing relationships, keeping power relations, protection and so on are influenced by regional characteristics, which include factors of determination of speech style such as generation, gender, solidarity, and jibunrashisa (like myself, personality) and so forth.  相似文献   

20.
A second look at the second messenger hypothesis   总被引:1,自引:0,他引:1  
D Lichtstein  D Rodbard 《Life sciences》1987,40(21):2041-2051
Several hundred hormones, neurotransmitters, growth factors and other "first messengers" bind to specific cell membrane receptors and induce a myriad of effects: short term, transport, metabolic, mitotic and regulation of thousands of specific genes. Yet, less than a dozen "second messengers" have been clearly established to date. Even allowing for the discovery of a large number of additional second messengers, there remains a paradox in terms of information-transfer within the cell: how can so many specific signals produce so many effects through so few relatively nonspecific intermediates? We consider several possible solutions to this paradox, including the hypothesis that signal specificity is encoded in part in the primary structure of the receptor.  相似文献   

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