ALBERT

Notes: Summary Love waves in a half space with one homogeneous elastic layer overlying a semiinfinite medium having elastic properties varying with depth has been considered. The frequency equation for small wave lengths has been obtained, considering general variation, and has been shown to involve the first three derivatives of the rigidity of the heterogeneous medium at its interface with the homogeneous layer.

Notes: Abstract A new species ofCandida was isolated from marine environment. It ferments glucose slowly. It assimilates cellobiose but does not split arbutin. It does not assimilate nitrate. Maximum temperature is ±28 C. The proposed name isCandida suecica.

Notes: Zusammenfassung Mit Hilfe von radioaktiv markiertem Prolin wird autoradiographisch das Vorkommen von Collagen im Matrixeiweiss pflanzlicher Zellkerne festgestellt.

Notes: Riassunto Sono state studiate le frequenze degli alleli al locusPl per la fosfatasi alcalina della placenta umana in 175 parti singoli verificatisi nella popolazione di Roma. Sono stati identificati tutti e 6 i fenotipi più comuni descritti in precedenza; la loro frequenza corrisponde a quella attesa secondo la legge diHardy-Weinberg. Le frequenze geniche sono risultate sovrapponibili a quelle riportate per le popolazioni Inglese e Svedese.

Notes: Summary The displacements and shearing stresses in an infinite medium are obtained for a finite line source, taken as the limit of a prolate ellipsoid with the shearing stresses prescribed on its surface. The results have been extended to the case of a semi-infinite medium by the method of images.

Notes: Zusammenfassung Das in einer früheren Arbeit aufgestellte Modell für die Strahlenwirkungen auf eine niohtsynchronisierte Population haploider Hefezellen, bei dem zwei verschieden strahlenempfindlicheAge-Intervalle angenommen wurden, kann durch die Methode der Einzelzellbeobachtung bestätigt werden. Die Strahlenwirkung auf den strahlenempfindlichen Zustand As führt danach zu einem Schaden, der stets bei der folgenden Teilung des Kernmaterials manifest wird. Die Wirkung auf den strahlenresistenteren Bereich AR führt zunächst zu einer induzierten Lagzeit sehr verschiedener Länge. Lange Lagzeiten sind bei solchen Zellen zu beobachten, die sich später zu Makrokolonien entwickeln können. Das legt den Schluß nahe, daß während dieser Lagzeit Gelegenheit für Reparaturvorgänge gegeben ist. Zellen mit kurzer induzierter Lagzeit bleiben in Gruppen mit 4–32 Zellen nach der Bestrahlung liegen, werden also nach wenigen durchgeführten Zellteilungen inaktiv. Das deutet auf einen genetischen Strahlenschaden in dieser Gruppe.

Notes: Abstract Females of Acheta domesticus were injected with H3-thymidine and H3-uridine at various stages of development in order to study DNA and RNA synthesis in the DNA body present in the oocytes. Staining with alkaline fast green, azure B and the Feulgen reaction were employed as cytochemical tests. The following main results were obtained. 1) The DNA body appears in the oogonia at interphase as a Feulgen positive spherical structure 2 microns in diameter and is seen in subsequent mitotic divisions as a slightly smaller structure of variable shape. H3-thymidine autoradiography discloses that the DNA present in this body is synthesised at a different time from the chromosomal DNA. 2) At interphase and during the early prophase of meiosis the DNA body increases in size becoming a large Feulgen positive sphere 6 microns in diameter. Small nucleoli are present within this body. The DNA of the body is complexed with histone as revealed by alkaline fast green staining. H3-thymidine labelling discloses that it is at these stages that the bulk of the DNA synthesis takes place in the body. 3) Every oocyte contains a DNA body, and no body of comparable size or shape seems to be present in the male meiotic prophase. 4) At pachytene and diplotene the DNA body acquires the appearance of a “puff”. Two zones can be distinguished inside the DNA body: (1) an inner core of DNA and an outer shell of RNA. The inner core is Feulgen positive and stains light green with azure B, the outer shell is Feulgen negative and stains purple-violet with azure B, as does the cytoplasm. From the inner DNA core many Feulgen positive fibrils radiate into the outer RNA shell. These fibrils appear unstained or slightly greenish with Azure B, forming a transparent network in a purple-violet background. This gives the body the typical appearance of a “puff”. H3-uridine incorporation reveals that the RNA synthesis occurs in the outer RNA shell of the body and in the chromosomes. RNase treatment removes the H3-uridine incorporated into these regions. 5) At the end of diplotene the DNA body starts to disintegrate. The DNA core breaks up into minor components and the outer RNA zone also begins to disintegrate. By late diplotene the whole body has vanished, releasing DNA, histone and RNA into the nucleus. Subsequently the nuclear envelope disintegrates as it regularly does at the end of prophase of meiosis. 6) The simplest interpretation of the above results is that the DNA body represents hundreds of copies of the genes of the nucleolar organizing region.