Pilfering of stored seeds and the relative costs of scatter-hoarding versus larder-hoarding in yellow pine chipmunks

Yellow pine chipmunks ( Tamias amoenus ) scatter-hoard food during summer and autumn but must form a larder as a winter food source before winter begins. Yellow pine chipmunks do not larder-hoard large quantities of food during the summer, apparently because a summer larder could not be defended from pilferers. We tested the assumption that the rate of pilferage from an unguarded larder would be significantly greater than the rate of pilferage from surface caches (which are also unguarded by yellow pine chipmunks) during the summer and autumn. Buried plastic buckets were used as artificial nests containing larders of 1000 sunflower seeds or 200 Jeffrey pine ( Pinus jeffreyi ) seeds. The pilferage of larder contents was monitored daily and compared to pilferage of surface caches. Animals (yellow pine chipmunks and deer mice, Peromyscus maniculatus ) removed sunflower seeds from caches much faster than from larders, but caches of Jeffrey pine seeds disappeared much more slowly than pine seeds in larders. Further, animals removed pine seeds from larders more quickly than they did sunflower seeds from larders. The difference between seed species was probably because sunflower seeds have much stronger odors, which rodents readily detect, and because chipmunks prefer pine seeds over sunflower seeds. Yellow pine chipmunks must spend a considerable portion of their time foraging for seeds and may not be able to defend a large larder during summer.     

Mögliche Beziehungen der optischen Aktivität zum Problem des Alterns

Summary The solubilities and other properties of compounds made by combination of optically active components, e.g. the solubilities of the salts made from the dextro-form of an acid and the dextro- or the laevo-form of a base are in some instancesextremely different. It is a consequence of these differences that in a living organism, containing optically active substance,the degree of optical purity of these substances is of outmost importance. The presence of undesired antipodes of any kind might fundamentally disturb the metabolism. It is also known that living organisms at least partly and continuously produce the optically active substances needed bysynthesis from optically inactive material.A kinetical and thermodynamical study of the conditions under which optically active substances can, with use of optically active catalysers, be synthetized from inactive material, shows that the degree of optical purity of the material synthetized is, even under the most favorable conditions, maximum in the beginning of the synthesis andis bound to decay when the synthesis is, chemically speaking,completed and if the synthetized material is left in contact with the catalyzer. Thus a racemization of the synthetized active material occurs in which the catalyzer which has originally produced this active substance actively accelerates the deterioration of its state of optical purity.The means are discussed by which the organism is able to delay this loss of optical purity; and it is shown that all poosible means to do so are indeed used by the organism. As these means can delay but never completely avoid the decay of optical purity, this decay, even if it be slow, i.e.an ageing of optical purity, is a necessity in the course of the life of a living organism. As a loss of optical purity must disturb the normal metabolism, this must, even if no other events occur, limit the individual life.Experimental evidence which would check the prediction of decay of optical purity with age is incomplete; in several instances, however, the experimental technique permits us to detect and to follow the occurrence of finite small amounts of undesired antipodes, e.g. of some amino acids in the proteins of living organisms.

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Vortrag, gehalten vor der Schweizerischen Gerontologischen Gesellschaft in Basel am 11. Dezember 1954.     

Alterations of tryptophan metabolism induced by sleep deprivation

Zusammenfassung Es wird gezeigt, dass Schlafentzug die Ausscheidung der 5-Hydroxyindolessigsäure und der Xanthurensäure vermehrt und diejenige der Antranilsäure herabsetzt.     

YidC mediates membrane protein insertion in bacteria

The basic machinery for the translocation of proteins into or across membranes is remarkably conserved from Escherichia coli to humans. In eukaryotes, proteins are inserted into the endoplasmic reticulum using the signal recognition particle (SRP) and the SRP receptor, as well as the integral membrane Sec61 trimeric complex (composed of alpha, beta and gamma subunits). In bacteria, most proteins are inserted by a related pathway that includes the SRP homologue Ffh, the SRP receptor FtsY, and the SecYEG trimeric complex, where Y and E are related to the Sec61 alpha and gamma subunits, respectively. Proteins in bacteria that exhibit no dependence on the Sec translocase were previously thought to insert into the membrane directly without the aid of a protein machinery. Here we show that membrane insertion of two Sec-independent proteins requires YidC. YidC is essential for E. coli viability and homologues are present in mitochondria and chloroplasts. Depletion of YidC also interferes with insertion of Sec-dependent membrane proteins, but it has only a minor effect on the export of secretory proteins. These results provide evidence for an additional component of the translocation machinery that is specialized for the integration of membrane proteins.     

宇宙学与战略"大思维"

宇宙学在近当代获得了长足发展,而这一发展正是孕育于强大而极富创造性的思维母体。从一般系统理论的角度来说,公司或政府机构等大型商业或政治组织的领导人可以利用宇宙学及其思维方法,进行战略性“大思维”,从而做出正确的决策。在本文中,作者不仅对宇宙学的具体理论和原则进行了归纳总结,而且还提出具体实例,以为这些领导人运用宇宙学进行战略高度的“大思维”提供佐证,从而进一步证明,“大思维”对于在复杂的现代组织中取得成功具有重要意义。     

Das statistische Problem der Gestalt fadenförmiger Moleküle

Ohne Zusammenfassung