IIB Supergravity and the E6(6) covariant vector-tensor hierarchy

IIB supergravity is reformulated with a manifest local USp(8) invariance that makes the embedding of five-dimensional maximal supergravities transparent. In this formulation the ten-dimensional theory exhibits all the 27 one-form fields and 22 of the 27 two-form fields that are required by the vector-tensor hierarchy of the five-dimensional theory. The missing 5 two-form fields must transform in the same representation as a descendant of the ten-dimensional `dual graviton'. The invariant E6(6) symmetric tensor that appears in the vector-tensor hierarchy is reproduced. Generalized vielbeine are derived from the supersymmetry transformations of the vector fields, as well as consistent expressions for the USp(8) covariant fermion fields. Implications are discussed for the consistency of the truncation of IIB supergravity compactified on the five-sphere to maximal gauged supergravity in five space-time dimensions with an SO(6) gauge group.Comment: 48 pages, added an extra affiliatio

Polypeptides traverse the mitochondrial envelope in an extended state

Most mitochondrial proteins are synthesized as precursors in the cytosol and imported through the contact sites between outer and inner mitochondrial membranes. The molecular mechanism of membrane translocation of precursor proteins is largely unclear. For this report, various hybrid proteins between portions of the precursor of cytochrome b2 and the entire dihydrofolate reductase (DHFR) were accumulated in mitochondrial contact sites. We unexpectedly found that about 30 amino acid residues of the polypeptide chain in transit were sufficient to span both membranes. This suggests linear translocation of the polypeptide chain and presents evidence for a high degree of unfolding of polypeptides traversing the mitochondrial membranes

Conditioning of Food Intake in the Mother - Kid - Relation in Goats

Titelblatt, Inhaltsverzeichnis, Lebenslauf Einleitung Aufgabenstellung Eigene Untersuchungen Statistische Methoden Ergebnisse Diskussion Schlussfolgerungen Zusammenfassung Summary Anhang LiteraturDie Konsequenzen der Futteraufnahme beeinflussen das Fressverhalten von Tieren. Junge Pflanzenfresser erwerben aber auch durch soziales Lernen eine Präferenz für ein von der Mutter gern gefressenes Futtermittel. In dieser Arbeit wird die Frage untersucht, ob diese konditionierte Präferenz durch das Beispiel der Mutter die spätere Futtermittelselektion der Kitze bestimmt, oder ob vielmehr das Kitz dem mütterlichen Beispiel zwar folgt, letztendlich jedoch das postingestive feedback aus dem Verdauungstrakt bestimmender Faktor für die Futterselektion des Kitzes ist. Die Hypothese war daher, dass das mütterliche Beispiel die Futterselektion ihrer Kitze nachhaltig beeinflusst, unabhängig vom postingestive feedback der Futtermittel. Fünfzehn Ziegenkitze wurden in eine Versuchsgruppe A und eine Versuchsgruppe B aufgeteilt. Den Kitzen wurden zweimal täglich für eine begrenzte Zeit jeweils zwei energiereiche Futtermittel angeboten; morgens zwei Futtermittel mit unterschiedlichem Gehalt an Tannin und abends Futtermittel mit unterschiedlichen Aromastoffen vermischt. Während einer mehrwöchigen Lernphase konnten die Kitze zunächst die Futtermittel zusammen mit der Mutterziege fressen. Danach wurde während zweier Testphasen die Futteraufnahme der Kitze ohne die Mutterziege gemessen. Allen Kitzen wurden während der Lernphase zwei der Futtermittel so angeboten, dass sie ein Futtermittel simultan mit der Mutter an der von der Mutter bevorzugten Futterstelle (Futterstelle mit maternaler Präferenz) fressen konnten oder ein anderes Futtermittel an einer Futterstelle fanden, an der die Mutterziege nur sehr wenig fraß (Futterstelle mit maternaler Aversion). Die Kitze der Versuchsgruppe A bekamen während der Lernphase an sechs Tagen morgens ein von der Mutterziege wenig gefressenes Futtermittel (Futtermittel mit relativer maternaler Aversion) an der Futterstelle mit maternaler Präferenz angeboten. Gleichzeitig wurde ein von der Mutterziege bevorzugtes Futtermittel an der Futterstelle mit maternaler Aversion angeboten. Die Kitze der Versuchsgruppe B dagegen bekamen das Futtermittel, das die Mutterziege bevorzugt fraß, an der Futterstelle mit maternaler Präferenz angeboten und ein von der Mutterziege wenig gefressenes Futtermittel an der Futterstelle mit maternaler Aversion. Zusätzlich wurden abends unterschiedlich aromatisierte Futtermittel entweder an der Futterstelle mit maternaler Präferenz oder Aversion angeboten. Während der anschließenden zwei Testphasen wurde die Futteraufnahme der Kitze beider Gruppen ohne die Mutterziege gemessen. Folgende Ergebnisse wurden erzielt: 1) Das Beispiel der Mutter beeinflusste während der Lernphase die Futterauswahl der Kitze (siehe Abb. 5-8, Abb. 17 und 20). Die von den Kitzen in wiederholten Versuchen während der Lernphase getroffene Futterwahl und die aufgenommene Futtermenge demonstrieren, dass die Futterselektion der Kitze durch die Wahl des Futterplatzes der Mutter beeinflusst war. 2) In Abwesenheit des Muttertieres (Testphasen) hatte die Futterselektion der Mutter keinen Einfluss auf die Futterselektion der Kitze (siehe Abb. 9-16). Die Selektion der Kitze erfolgte nach den negativen postingestiven Konsequenzen der Aufnahme von Futtermitteln. Die Konzentration an Tannin im Futtermittel (1% und 8%) hatte einen negativen Effekt auf die Futteraufnahme. Es konnte gezeigt werden, dass Futtermittel deren Aufnahme sich im postingestiven feedback Aufnahme nicht unterschied (aromatisierte Futtermittel), auch in gleichen Mengen von den Kitzen aufgenommen wurden. 3) Während der Phase, in der Kitze lernen eine geeignete Diät zu selektieren, beeinflusst das Beispiel der Mutterziege die Wahl des Futterplatzes und dadurch die Futterselektion des Kitzes. Indem Mutterziege und Kitz simultan fressen (co-feeding), erhöht sich für das Kitz der Bekanntheitsgrad derjenigen Pflanzen, welche die Mutterziege selektiert. Die Mutterziege überträgt ihre Futterselektion auf ihre Kitze indem sie deren Neophobie vor Futtermitteln verringert. 4) Negative postingestive Konsequenzen der Aufnahme eines Futtermittels begrenzen die individuell aufgenommene Futtermenge bei Ziegenkitzen in Abwesenheit der Mutter. Die Übertragung der Futterselektion von Mutterziege auf das Kitz entspricht daher einer Nachahmung des mütterlichen Verhaltens, nicht aber einer Nahrungsprägung durch die Mutter. Aus den Ergebnissen lässt sich schließen, dass das Training der Kitze mit ihren Müttern nicht zu einer permanenten Nachahmung mütterlicher Futterselektion führt. Vielmehr sind es die negativen Konsequenzen der Futteraufnahme die die Futterselektion bestimmen. Das Lernen am Beispiel der Mutter spielt demgegenüber nur eine untergeordnete Rolle.Conditioning of Food Intake in the Mother-Kid-Relation in Goats This study investigated the consequences of food intake and social learning, both of which have a major influence on foraging behavior. Young herbivores acquire a preference for food that is preferred by their mothers. This preference which is acquired early in life from the mother's example may significantly determine food selection later in life. In addition to the mother's influence, postingestive feedback from the gastro-intestinal tract, such as the negative consequences of ingesting food with high concentration of tannin have a major influence on diet selection. The conditioning of kid's food intake by mother's example may compete with the learning of postingestive consequences in kid's food selection learning. We determined whether goat kids would follow their mother's example even if negative postingestive feedback favored a different food selection. We hypothesized that the mother's example influences food selection of her kids, persistently and independently of the food's postingestive feedback. Fifteen goat kids were divided into two groups. High- energy foods were given twice daily for a 5-minute period six times during the learning period with their mothers. In this period the kids could observe their mother's diet selection. This was followed by two test periods without their mothers for five and four days, respectively. Two foods differing in tannin concentration were used to provoke two different consequences after intake; two foods differing in flavor were used as distinguishable foods without differences in consequences after intake. In each feeding the kids had a choice between two foods. For the morning feeding the choice was between two foods differing in tannin concentration, in the evening the feeding choice was between two foods differing in flavor. During the learning period the kids were four to eight weeks of age. After this time the kids underwent two test periods. The first test phase, which lasted five days occurred when the kids were 11 weeks old; the second test phase, which lasted four days, occurred when the kids were 14 weeks old. During these periods all the kid's food intake of tannin containing or flavor containing high-energy food was measured. During the initial learning period food was simultaneously given to the mother and her kid in such a manner that they could eat together from one of two food boxes. These food boxes were fixed at two feeding places three meters apart in a pen. The boxes were subdivided with two plastic containers that were open either to the mother or to the kid. With the access to their food separate mother and kid could eat at the same place even though each received different food. Kids of group A were offered food that the mother would reject in a feeding place of mother's preference, whereas both kids and mothers of group B were offered identical foods at both feeding places. We compared food intake of kids during learning period and test periods. The following results were obtained: 1) The mother's example influenced food selection of the kids in the learning period. The kid's food selection was positively influenced by their mother's choice of a feeding place. 2) The mother influenced their kid's food selection when she was present, but the mother's prior example had no influence on the kid's later diet-selection. In the mother's absence the kid's diet selection was consistent with food selection learning from postingestive feedback. The concentration of tannin in the food had a negative influence on food selection, whereas different aromas had no influence on food selection, even though the mother favored one aroma by choosing a feeding place during the learning period. 3) When developing feeding behavior, the example of the mother's diet selection competes with learning from postingestive consequences. By feeding simultaneously, the mother's example increases the familiarity with her selection and facilitates similar diet selection. 4) However, if a food causes negative postingestive feedback in the kid, their own experiences determine the kid's diet selection despite their mother's example. Negative postingestive feedback limits food intake in goat kids in the absence of a mother. These results support the fact that the training of goat kids by manipulating their food choice with their mother's example does not result in a permanent change in diet selection. Food intake is limited by the capacity of the animal to cope with the negative postingestive consequences, learning from mother's example has a minor influence on food selection

Energy requirements for unfolding and membrane translocation of precursor proteins during import into mitochondria

ATP is involved in conferring transport competence to numerous mitochondrial precursor proteins in the cytosol. Unfolded precursor proteins were found not to require ATP for import into mitochondria, suggesting a role of ATP in the unfolding of precursors. Here we report the unexpected finding that a hybrid protein containing the tightly folded passenger protein dihydrofolate reductase becomes unfolded and specifically translocated across the mitochondrial membranes independently of added ATP. Moreover, interaction of the precursor with the mitochondrial receptor components does not require ATP. The results suggest that ATP is not involved in the actual process of unfolding during membrane translocation of precursors. ATP rather appears to be necessary for preventing the formation of improper structures of precursors in the cytosol and for folding of imported polypeptides on (and release from) chaperone-like molecules in the mitochondrial matrix

Translocation arrest by reversible folding of a precursor protein imported into mitochondria

Passage of precursor proteins through translocation contact sites of mitochondria was investigated by studying the import of a fusion protein consisting of the NH2-terminal 167 amino acids of yeast cytochrome b2 precursor and the complete mouse dihydrofolate reductase. Isolated mitochondria of Neurospora crassa readily imported the fusion protein. In the presence of methotrexate import was halted and a stable intermediate spanning both mitochondrial membranes at translocation contact sites accumulated. The complete dihydrofolate reductase moiety in this intermediate was external to the outer membrane, and the 136 amino acid residues of the cytochrome b2 moiety remaining after cleavage by the matrix processing peptidase spanned both outer and inner membranes. Removal of methotrexate led to import of the intermediate retained at the contact site into the matrix. Thus unfolding at the surface of the outer mitochondrial membrane is a prerequisite for passage through translocation contact sites. The membrane-spanning intermediate was used to estimate the number of translocation sites. Saturation was reached at 70 pmol intermediate per milligram of mitochondrial protein. This amount of translocation intermediates was calculated to occupy approximately 1% of the total surface of the outer membrane. The morphometrically determined area of close contact between outer and inner membranes corresponded to approximately 7% of the total outer membrane surface. Accumulation of the intermediate inhibited the import of other precursor proteins suggesting that different precursor proteins are using common translocation contact sites. We conclude that the machinery for protein translocation into mitochondria is present at contact sites in limited number

Corporate Finance in Europe from 1986 to 1996

After publishing its first report in September 1997, the Own Funds Working Group, in agreement with the European Committee of Central Balance Sheet Offices, decided to continue its work in order to gain a better understanding of the differences in financing structures between countries. To this end, the Group decided firstly to broaden the review period from 1986 to 1996. The compilation of figures and ratios over a longer period is advantageous in a number of ways. It not only enables an assessment of trends in financing structures in each country, but also of any changes in the ranking of the different countries involved. Furthermore, it gives an insight into the influence of cyclical and structural factors on this ranking. The Group also set itself the objective of not only taking a closer look at the influence of institutional factors The study was based, as the previous study, on incorporated companies (partnerships and sole proprietorships are therefore excluded) of the manufacturing industry, which is uniformly defined across all the countries. Once again, five size brackets according to turnover expressed in euros are analyzed. The size-based approach is essential because the aggregate values conceal the diversity of the situations in the various countries, especially in Germany where the results are strongly influenced by large firms. The two statistical parameters used are the weighted mean and the median. Moreover, to gain a better understanding of the influence of financing needs, assets have been broken down into their main items. As previously, efforts have been made to align methodologies so that the analyses cover variables that are as homogenous as possible from country to country.corporate finance, capital structure, europe, financial systme, credit, bankrutcy

Antifolding activity of hsp60 couples protein import into the mitochondrial matrix with export to the intermembrane space

Cytochrome b2 reaches the intermembrane space of mitochondria by transport into the matrix followed by export across the inner membrane. While in the matrix, the protein interacts with hsp60, which arrests its folding prior to export. The bacterial-type export sequence in pre-cytochrome b2 functions by inhibiting the ATP-dependent release of the protein from hsp60. Release for export apparently requires, in addition to ATP, the interaction of the signal sequence with a component of the export machinery in the inner membrane. Export can occur before import is complete provided that a critical length of the polypeptide chain has been translocated into the matrix. Thus, hsp60 combines two activities: catalysis of folding of proteins destined for the matrix, and maintaining proteins in an unfolded state to facilitate their channeling between the machineries for import and export across the inner membrane. Antifolding signals such as the hydrophobic export sequence in cytochrome b2 may act as switches between these two activities