Analysis of the transcriptional program governing meiosis and gametogenesis in yeast and mammals

During meiosis a competent diploid cell replicates its DNA once and then undergoes two consecutive divisions followed by haploid gamete differentiation. Important aspects of meiotic development that distinguish it from mitotic growth include a highly increased rate of recombination, formation of the synaptonemal complex that aligns the homologous chromosomes, as well as separation of the homologues and sister chromatids during meiosis I and II without an intervening S-phase. Budding yeast is an excellent model organism to study meiosis and gametogenesis and accordingly, to date it belongs to the best studied eukaryotic systems in this context. Knowledge coming from these studies has provided important insights into meiotic development in higher eukaryotes. This was possible because sporulation in yeast and spermatogenesis in higher eukaryotes are analogous developmental pathways that involve conserved genes. For budding yeast a huge amount of data from numerous genome-scale studies on gene expression and deletion phenotypes of meiotic development and sporulation are available. In contrast, mammalian gametogenesis has not been studied on a large-scale until recently. It was unclear if an expression profiling study using germ cells and testicular somatic control cells that underwent lengthy purification procedures would yield interpretable results. We have therefore carried out a pioneering expression profiling study of male germ cells from Rattus norvegicus using Affymetrix U34A and B GeneChips. This work resulted in the first comprehensive large-scale expression profiling analysis of mammalian male germ cells undergoing mitotic growth, meiosis and gametogenesis. We have identified 1268 differentially expressed genes in germ cells at different developmental stages, which were organized into four distinct expression clusters that reflect somatic, mitotic, meiotic and post-meiotic cell types. This included 293 yet uncharacterized transcripts whose expression pattern suggests that they are involved in spermatogenesis and fertility. A group of 121 transcripts were only expressed in meiotic (spermatocytes) and postmeiotic germ cells (round spermatids) but not in dividing germ cells (spermatogonia), Sertoli cells or two somatic control tissues (brain and skeletal muscle). Functional analysis reveals that most of the known genes in this group fulfill essential functions during meiosis, spermiogenesis (the process of sperm maturation) and fertility. Therefore it is highly possible that some of the �30 uncharacterized transcripts in this group also contribute to these processes. A web-accessible database (called reXbase, which was later on integrated into GermOnline) has been developed for our expression profiling study of mammalian male meiosis, which summarizes annotation information and shows a graphical display of expression profiles of every gene covered in our study. In the budding yeast Saccharomyces cerevisiae entry into meiosis and subsequent progression through sporulation and gametogenesis are driven by a highly regulated transcriptional program activated by signal pathways responding to nutritional and cell-type cues. Abf1p, which is a general transcription factor, has previously been demonstrated to participate in the induction of numerous mitotic as well as early and middle meiotic genes. In the current study we have addressed the question how Abf1p transcriptionally coordinates mitotic growth and meiotic development on a genome-wide level. Because ABF1 is an essential gene we used the temperature-sensitive allele abf1-1. A phenotypical analysis of mutant cells revealed that ABF1 plays an important role in cell separation during mitosis, meiotic development, and spore formation. In order to identify genes whose expression depends on Abf1p in growing and sporulating cells we have performed expression profiling experiments using Affymetrix S98 GeneChips comparing wild-type and abf1-1 mutant cells at both permissive and restrictive temperature. We have identified 504 genes whose normal expression depends on functional ABF1. By combining the expression profiling data with data from genome-wide DNA binding assays (ChIPCHIP) and in silico predictions of potential Abf1p-binding sites in the yeast genome, we were able to define direct target genes. Expression of these genes decreases in the absence of functional ABF1 and whose promotors are bound by Abf1p and/or contain a predicted binding site. Among 352 such bona fide direct target genes we found many involved in ribosome biogenesis, translation, vegetative growth and meiotic developement and therefore could account for the observed growth and sporulation defects of abf1-1 mutant cells. Furthermore, the fact that two members of the septin family (CDC3 and CDC10 ) were found to be direct target genes suggests a novel role for Abf1p in cytokinesis. This was further substantiated by the observation that chitin localization and septin ring formation are perturbed in abf1-1 mutant cells

Kategorien von Geschlecht in Lehrwerken Deutsch als Zweit- und Fremdsprache.

Im wissenschaftlichen Diskurs gilt Gender, und die damit verbundene Heteronormativität, mittlerweile als fest etablierte Kategorie. Auf ähnliche Weise scheint sich Gender auch im Alltag der Mehrheitsgesellschaft konstituiert zu haben, wenngleich sich schnell herauskristallisieren lässt, dass die Legitimation dieser eigentlich höchst komplexen Kategorien zumeist in Alltagsmythen und Stereotypen fußt. Auch wenn dieser Diskurswandel insgesamt nicht überall auf Begeisterung stößt , erweckt er doch den Anschein, dass es in den meisten Bereichen des Lebens einen Platz gefunden hat. Das lässt sich auch an der riesigen Menge an populärwissenschaftlichen Publikationen feststellen. Wenn sich mehr Verlage diesem Thema anzunehmen scheinen, sollte dies auch für Lehrwerke für den fremdsprachlichen Erwerb wie Deutsch als Fremdsprache (DaF) oder Deutsch als Zweitsprache (DaZ) gelten. Im Rahmen dieser Masterarbeit soll ausgehend von diesen Überlegungen untersucht werden, wie und ob die Kategorie Geschlecht in Deutsch als Zweit- und Fremdsprache Lehrwerken konstruiert und perpetuiert wird. Es soll eine exemplarische Analyse anhand des Lehrwerk Schritte plus Neu A1.1 durchgeführt werden, um aufzuzeigen, welche sozialen Praktiken zur Festigung des zweigeschlechtlichen Diskurse genutzt werden. Da es sich bei dem gewählten Lehrwerk um ein für den Integrationskurs in Deutschland zugelassenes Lehrwerk handelt, wird sich die Arbeit hauptsächlich auf den deutschsprachigen Diskurs beschränken. Zusätzlich muss außerdem die macht- und herrschaftskritische Bedeutung dieses Kurses mit einbezogen werden

Deutschland gefährdet Europa : wie es so weit kommen konnte und was dagegen getan werden muss

The development of venture capital industry is not only about the effective operation of venture capital firm, but also its supporting environments. The venture capital firms in different countries have different operation modes, for instance, the organizational structure, the source of finance and the investment behavior. The reason of the differences is that the venture capital supporting environments such as economy, culture, laws and regulations are different in various countries.   The objective of this research is to study the venture capital supporting environments in China and analyze the role of government on how to improve these supporting environments. After research questions are decided, the author analyzes and combines the selected previous researches in different countries in order to build a more systematic, scientific and complete theoretical framework to conduct the case study in China.   In the case study, all seven venture capital supporting environments in China are studied. By analyzing the facts, the author finds out that some environments such as laws and policies and financial environment have developed rapidly in past years and become more and more adapt to the development of venture capital. However, some other environments, especially the culture environment have negative effects on venture capital and can not be easily changed within a short period of time. Based on these findings, the author tries to find out some possible actions that the government can do to reduce these limitations and improve the venture capital supporting environments.     Key words: venture capital; supporting environment; venture business; venture capitalist

LOGISTICAL COSTS AND STRATEGIES FOR WHEAT SEGREGATION

Special segregations that provide unique qualities for end use products are being specified by buyers. As users of wheat become more specific about quality, the number of quality segregations that the logistical pipeline must accommodate increases. The additional cost of increased grain segregations will influence the optimal level of wheat variety segregations marketed in a supply chain. The primary objective of this research is to develop a model that captures the logistical costs of increased grain segregations in the marketing system. A simulation model was developed to add logistical uncertainty in demand, receipts, rail deliveries, and transit time. Sensitivities were conducted on certain variables to determine their effects on logistical costs. Logistical costs increase as more segregations are added. In addition, increasing uncertainty into the system raises logistical costs. Pipeline configuration also affects costs as the number of categories/storage bins present at origin may differ from the wheat categories demanded or the number of storage bins present at the export elevator.wheat, segregations, Crop Production/Industries,

LOGISTICAL COSTS AND RISKS OF MARKETING GENETICALLY MODIFIED WHEAT

Genetically modified (GM) grains have increased in importance. Moving biotech grains from producers to processors is a challenge for the grain handling system that could involve increased segregations. The objective of this research is to determine how testing strategies affect the logistical costs of a grain pipeline when GM wheat is present. A logistical model was developed and simulated to analyze impacts of uncertainty in demand, receipts, test accuracy, rail deliveries, and transit time. Sensitivities were conducted on certain variables to determine their effects on logistical costs. Analysis revealed that logistical costs are impacted by the number of quality categories and uncertainties in the system. Adding GM grains increased costs due to testing requirements and increased segregation demands as the number of wheat categories rises.Genetically Modified (GM) Grains, Logistical Costs, Testing, Risk, Segregation, Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,

Linking Europe - The Role of the Swiss Electricity Transmission Grid until 2050

The aim of this paper is to evaluate the role of the Swiss electricity transmission system and the planned network extensions in the context of Central European electricity market developments and thereby the Swiss and European energy transitions. In addition, we conduct a sensitivity analysis of delayed grid investments for Swiss and European network projects, respectively. By deriving a quantification of potential costs and system stability impacts due to delayed network investments, we can identify whether the currently observed lag in many energy investments poses a threat to achieving the envisioned energy transitions

Low-temperature formation of cubic beta-PbF(2): precursor-based synthesis and first-principles phase stability study

A precursor-based approach to the cubic beta-phase of PbF(2) was developed and allowed the preparation of this high-temperature phase well below the temperature for transition from the orthorhombic alpha- to the cubic beta-phase. The formation of beta-PbF(2) from the molecular precursors Pb[Se(C(6)H(2)(CF(3))(3))](2) and Pb(C(6)H(2)(CF(3))(3))(2) is facilitated by the presence of several short Pb center dot center dot center dot F contacts in these molecules. The cubic form of PbF(2) was obtained as macroscopic crystals as well as nanoparticulate powder. Its formation at relatively low temperature suggested a theoretical re-investigation of the phase stabilities of the two polymorphs. The theoretical results from the Kohn-Sham density functional theory indicate that the energy content for the beta-phase is slightly lower than the one for the alpha-phase, by 0.5-1.7 kJ mol(-1) depending on the density functional used (zero-point vibrational energy correction included)

Das Preisfindungssystem von Genossenschaftsmolkereien

Mit dem voraussichtlichen Ende der Milchquote im Wirtschaftsjahr 2014/2015 entfällt das hoheitliche Milchmengenregime (FAHLBUSCH ET AL. 2009, LATACZ-LOHMANN/ HEMME 2008, 2007, EU-KOMMISSION 2007). Dies bedeutet einen weitreichenden Einschnitt in die Rahmenbedingungen der europäischen Milchwirtschaft, da die vertraglichen Vereinbarungen der Milchlieferung neu geordnet werden müssen. Rund zwei Drittel der in Deutschland erzeugten Milch werden von Genossenschaften verarbeitet und vermarktet (DRV o.J.). Damit wird die bedeutende Stellung der Genossenschaftsmolkereien in einer der größten Branchen (Umsatz 2008: 26,66 Mrd. Euro) der deutschen Ernährungsindustrie deutlich (BVE 2009). Die Beziehung zwischen Milchlieferanten und der genossenschaftlichen Molkerei ist durch die Besonderheit gekennzeichnet, dass die Milcherzeuger sowohl Lieferanten als auch Anteilseigner der Molkerei sind (GERLACH ET AL. 2005)..