Selective purification of the thiol peptides of myosin

1. A method for selective purification of thiol peptides is described. Thiol groups in a protein are treated with radioactive cystine by disulphide-thiol interchange. The labelled cystine peptides in a digest can then be fractionated for peptide ;maps'. Performic acid oxidation of paper strips containing the radioactive peptides followed by further ionophoresis yields the purified cysteic acid peptides. 2. The thiol peptides in a peptic digest of cystine-exchanged myosin were purified in this way, and their amino acid sequences were determined. 3. The conclusion that myosin contains at least 16, and probably between 20 and 22, unique thiol sequences indicates that the molecule consists of two chemically equivalent components.     

Zoosporic fungi of Oceania

Summary In a further study of the zoosporic fungi of Oceania three new species of Rhizophydium, R. rarotonganensis, R. angulosum, and R. condylosum were isolated on various substrata from soil. Rhizophydium rarotonganensis is a parasite of Nowakowskiella profusa and causes marked local hypertrophy of the rhizomycelium. Rhizophydium angulosum occured on bleached corn leaves and pollen grains and is characterized by predominantly angular sporangia with bush-like, finely branched rhizoids, and small zoospores. It differs from R. subangulosum by its saprophytic nature, inability to infect blue-green and green algae, and its ability to grow in axenic culture on synthetic media. Rhizophydium condylosum is keratinophilic and develops in great abundance on human hair, snake skin and other keratinic substrata. It is characterized primarily by spherical to ovoid sporangia with 1 to 30 exit pepillae which give them a knobby appearance.This study has been supported by a grant from the National Science Foundation, Washington, D.C.     

XX/XO-Mosaik bei einem männlichen Individuum mit Kleinwuchs und Hypospadie

Zusammenfassung Bei einem normal intelligenten, kleinwüchsigen, 219/12 jährigen Mann mit Hypospadie, fraglicher rudimentärer Vagina und hypergonadotropem Hypogonadismus findet man bei der Biopsie des nur 7 ml großen linken Hodens eine gleichförmige tubuläre Atrophie mit Fehlen des Keimepithels und eine diffuse, kleinherdige Leydigzellwucherung. Sex-Chromatin in den Leydigzellen, im Mundabstrich und Drumsticks negativ. Karyotyp in den Lymphocyten und im Knochenmark normal weiblich (46,XX), in den Fibroblasten jedoch 45,XO.Somit weist dieser Patient Testesgewebe auf, das Y-Chromosom ist aber unauffindbar. Zur Klärung dieser Diskrepanz scheint das Vorhandensein einer dritten, zahlenmäßig stark in den Hintergrund tretenden, ein Y enthaltenden Zellpopulation die naheliegendste Hypothese zu sein.Eine Zwillingsschwester kam im Neugeborenenalter ad exitum; die Blutgruppenuntersuchungen beim Patienten und seiner Familie machen aber einen Blutchimärismus sehr unwahrscheinlich.Das klinische Bild unseres Patienten ist vollkommen verschieden von demjenigen, das beim XX/XO-Mosaik üblicherweise beobachtet wird und läßt sich auch vom klassischen Klinefelter-Syndrom deutlich abgrenzen. Es zeigt Ähnlichkeiten mit einigen Fällen von XO/XY-Mosaik.

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Summary In a normally intelligent man of 219/12 years the following main physical findings were present: short stature, hypospadias, possibly a rudimentary vagina, hypergonadotropic hypogonadism, small testis (7 ml) with tubular dystrophy consisting in absence of germinal epithelium and localized proliferation of Leydig's cells. Sex chromatin in buccal mucosa cells was negative; no drumsticks were found in neutrophils. The karyotype in lymphocyte cultures and bone-marrow preparations was 46,XX; in several independent fibroblast cultures 45,XO.The most likely explanation for the presence of testicular tissue seems to be the existence of an undiscovered cell population containing a Y-chromosome.A twin sister of the patient died in early infancy; blood group investigations gave no indications for the presence of blood chimerism.The clinical picture of this patient is entirely different from that of the usual XX/XO mosaics, it also clearly differs from Klinefelter's syndrome but shows some similarities to cases of XO/XY mosaicism.

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Direktor: Prof. Chr. Hedinger     

Ultrastructural evidence for the biflagellate origin of the uniflagellate fungal zoospore

Summary The morphological similarities between the kinetosome and the second centriole of the zoospores of Phlyctochytrium kniepii and P. punctatum (Chytridiomycetes) suggest that the second centriole in the chytrid zoospore is a vestigial flagellum base. It is suggested that the term vestigial kinetosome may also be used when referring to the structure which is presently termed the second centriole of the chytrid zoospore. Morphological similarities between the chytrid zoospores of P. kniepii and P. punctatum and the zoospores of Rhizidiomyces apophysatus (Hyphochytridiomycetes) are noted. The possible biflagellate origin of fungi with uniflagellate zoospores is discussed. The third fiber (C fiber) of the kinetosome triplet is shown to form as an outgrowth of the B fiber of the kinetosome doublet.     

An electron microscope study of nebenkern formation and differentiation in spermatids of Murgantia histrionica (Hemiptera, Pentatomidae)

Mitochondria in early spermatids of many insects aggregate and form a round body, the nebenkern. The nebenkern undergoes a structural differentiation and then divides into two separate equal-sized bodies. In the present study, nebenkerns of Murgantia histrionica, a Hemipteran insect, were reconstructed using electron micrographs of serial sections to determine how the mitochondria transform into the two separate bodies. Newly formed nebenkerns are made of one piece, an anastomosis of rod-like segments. Some segments interconnect to join networks of rings. Each network interlocks with another similar network, but networks which interlock are connected with each other by other segments of the nebenkern. Later, the entire nebenkern is made of two unconnected and interlocked networks of rings. The nebenkern appears to remain bipartite during subsequent differentiation. Since the two pieces are interlocked, breaks must occur before the pieces can separate. As breaks occur, each network transforms into a set of curved sheets, producing a nebenkern made of four concentric layers. The three outer layers are each made of two curved sheets which surround a bipartite central core. The surface sheets meet at a furrow in the surface of the nebenkern; segments in each layer are roughly symmetrical with each other about the plane in which the furrow lies. Rod-like segments join alternate segments. The number of layers then decreases to three, and later, to two. These nebenkerns resemble four-layered nebenkerns, but fewer connections between alternate segments are present. The two pieces constituting the nebenkern probably separate after most of the latter connections disappear. Hypotheses to account for the observed changes in nebenkern structure are presented.