The chemical synthesis of polysaccharides : Part III. Synthesis of 6-O-α-D-mannopyranosyl-D-mannose and 4-O-α-D-mannopyranosyl-D-mannose. Isolation of A (1→6)-linked D-mannan

When 1,2,3,4-tetra-O-acetyl-α-D-mannopyranose was fused with a catalytic amount of toluene-p-sulphonic acid, 6-O-α-D-mannopyranosyl-D-mannose and 4-O-α-D-mannopyranosyl-D-mannose were isolated after deacetylation of the reaction mixture. No β-D-linked disaccharide was detected in the reaction mixture. When the corresponding β-D-tetra-acetate was fused with zinc chloride as catalyst, higher oligomers were formed, and a D-mannan was isolated and shown to be mainly an α-(1→6)-linked polymer having d.p. of 10. With 5% of zinc chloride, the α-D-tetra-acetate showed oligosaccharide formation, and yielded a smaller proportion of a (1→6)-linked D-mannan.     

Studies with Lectins on the Surface Carbohydrate Structures of Mycoplasma Membranes

The surface carbohydrate structures on the cell membranes of various mycoplasma species have been investigated by using lectins, which are sugar-specific proteins. Carbohydrate structures presumably bound to glycolipids, with both galactose and glucose units, were found to be exposed on the surface of Mycoplasma pneumoniae and its temperature-sensitive mutants, M. mycoides var. mycoides and capri, M. pulmonis, M. gallinarum, and M. gallisepticum. Lipid-bound glucose was found on M. neurolyticum. The possible relationship of the lipid-bound surface carbohydrate groups to the known serological cross-reactions and lipid compositions of the various mycoplasma species is discussed. Intact Acholeplasma laidlawii and M. fermentans have no lectin-binding sites exposed on their surfaces; galactose groups were discovered only after Pronase digestion of the organisms, suggesting that their glycolipids are hidden under a protein layer. Neither intact nor Pronase-digested M. hominis reacted with the lectins; this is fully consistent with the lipid composition of this organism, which contains glycolipids. The lectins from Vicia cracca and Phaseolus vulgaris, which react with N-acetyl-galactosamine groups, agglutinated M. gallinarum, M. gallisepticum, M. mycoides var. capri, and M. pulmonis. The agglutinability was lost after Pronase treatment, indicating that the corresponding carbohydrates are presumably protein bound. They may be correlated with the extracellular structures observed by electron microscopy of both sectioned and negatively stained mycoplasma species.     

RESOLUTION OF THREE DISTINCT POPULATIONS OF NERVE ENDINGS FROM RAT BRAIN HOMOGENATES BY ZONAL ISOPYCNIC CENTRIFUGATION

Conditions have been established for the fractionation of subcellular components of rat forebrain homogenates by zonal isopycnic equilibration in continuous sucrose density gradients using a B-XIV rotor. The fractions were analyzed biochemically and by ultra-structural morphometry. Starting from postnuclear supernates of forebrain homogenates, it has been possible to resolve three distinct populations of nerve endings from one another, as well as from free mitochondria and myelin fragments. The three types of nerve endings differ in their apparent specific gravity, their biochemical properties, and their ability selectively to accumulate exogenous transmitter substances in vitro. These three particle populations are likely to represent, in order of increasing modal equilibrium density, (a) cholinergic nerve endings, characterized by their high content of acetylcholine, (b) γ-amino butyric acid (GABA)-containing nerve endings with high glutamate decarboxylase activity and the ability to accumulate exogenous GABA, (c) adrenergic nerve endings that accumulate exogenous dopamine and noradrenaline and exhibit high monoamine oxidase activity.     

Seasonal variation in the birth of children with aneuploid chromosome abnormalities

Summary The seasonal variation in frequency of birth of 297 patients with karyotypes 47,XXY, 47,XYY, 47,XXX and 45,X registered in the Danish Cytogenetic Central Register until January 1st, 1971, was significantly different from the variation expected. The frequency of conception was higher than expected in June, July and August and lower in September, October and December. The variation in frequency of birth of the 791 patients with trisomy 21 was not significantly different from the expected value.There was no coincidence between the peak frequency of conception of children with aneuploid sex chromosome abnormalities and the peak frequency of a number of infectious diseases.It is concluded that the cause of the seasonal variation in frequency of conception and birth of children with aneuploid sex chromosome abnormalities is unknown. A number of possible factors are mentioned.

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Zusammenfassung Bei den 297 Patienten mit Karyotypen 47,XXY, 47,XYY, 47,XXX und 45,X, die bis zum 1. Januar 1971 im Dänischen Cytogenetischen Centralergister registriert worden sind, unterschied sich die jahreszeitliche Variation in der Geburtenhäufigkeit signifikant von der erwarteten Variation. Die Konzeptionshäufigkeit war in den Monaten Juni, Juli und August erhöht und im September, Oktober und Dezember erniedrigt, wohingegen die Variation in der Geburtenhäufigkeit von 791 Patienten mit Karyotypen 47,XX order XY,+21 Abnormitäten nicht signifikant unterschiedlich von der erwarteten Variation war.Es fand sich kein Zusammentreffen zwischen dem Häufigkeitsgipfel der Konzeption von Kindern mit aneuploiden Geschlechtschromosomenabnormitäten und dem Gipfel einer Reihe von Infektionskrankheiten.Daraus wird geschlossen, daß die Ätiologie der jahreszeitlichen Variation der Konzeptions-häufigkeit und Geburten von Kindern mit aneuploiden Geschlechtschromosomenabnormitäten unbekannt ist. Eine Reihe möglicher Faktoren wird erwähnt.

     

Gonadal Growth in Embryos of Sex reversed Mice

Gonadal volumes were measured in litters of mouse embryos, aged 15 and 16 days, which were segregating for the Sex reversed factor. The testes of XY embryos were much larger than the ovaries of female embryos and the testes of XX Sex reversed males were almost, but not quite, as large as those of XY males. One of the 13 Sex reversed embryos had ovotestes.
It is concluded that the Sex reversed factor causes an increase in the growth rate of XX gonadal rudiments and that this is a necessary prerequisite for testicular differentiation. It is further postulated that the failure of spermatogenesis seen in adult Sex reversed , XX males is a result of the suboptimal growth rate of the gonads, compared to that of normal testes seen in the embryos. The formation of ovotestes may result from a growth rate which is at a lower limit of that necessary for testicular differentiation.     

Action of Ribonuclease T1 on 30S Ribosomes of Escherichia coli and Its Role in Sequence Studies on 16S Ribonucleic Acid

Two large ribonucleic acid (RNA) fragments have been obtained from T1-RNase-treated 30S ribosomes of Escherichia coli. One fragment, about 475 nucleotides long, contains all the unique oligonucleotides found by Fellner and associates in sections of 16S RNA designated P, E, E', and K, and one-half the large oligonucleotides of section A. The other large fragment is about 300 nucleotides long and contains the oligonucleotides found in sections C, C', C'. The isolation of these large fragments seems to confirm the arrangement of sections within 16S RNA. There are also recovered from nuclease-treated ribosomes three small fragments, one (120 nucleotides long) from the 5' end, one (26 nucleotides long) from the 3' OH end of the chain, and another section (66 nucleotides long) from the middle of the 16S RNA chain. Small molecular weight material is also generated by nuclease treatment, and about half this material is derived from a region close to the 3' OH end of the 16S RNA chain. This indicates that the most accessible part of the rRNA of E. coli 30S ribosomes is a region 100 to 150 nucleotides long near the 3' end of the chain. A general scheme is proposed to explain the generation of the various-sized RNA products from the rRNA of the 30S ribosome.     

Father and son with karyotype 47,XY,?Yq-

Summary A 22-year-old man and his father, both with 47 chromosomes, an extra small metacentric chromosome and the presumptive karyotype of 47,XY, ?Yq-, are presented.Literature concerning cases with 47 chromosomes and a small metacentric chromosome is reviewed and discussed. It is concluded that it is unlikely that persons with 47 chromosomes and an extra small metacentric chromosome constitute a new cytogenetic disease the syndrome of the metacentric microchromosome, as suggested by Abbo and Zellweger (1970).Persons with 47 chromosomes and an extra small metacentric chromosome have most probably a great variety of chromosomal aberrations, some of autosomal and some of sex chromosomal origin.

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Zusammenfassung Es wird über einen 22jährigen Mann und seinen Vater berichtet. Beide hatten 47 Chromosomen: Ein zusätzliches metazentrisches kleines Chromosom und den angenommenen Karyotyp 47,XY, ?Yq-.In diesem Zusammenhang wird die Literatur über Fälle mit 47 Chromosomen und einem kleinen metazentrischen Extrachromosom diskutiert. Die Autoren gelangen zu der Schlußfolgerung, es sei unwahrscheinlich, daß eine neue cytogenetisch charakterisierte Krankheit, das Syndrom des metazentrischen Mikrochromosoms, wie Abbo u. Zellweger (1970) es annehmen, in der Tat existiert. Personen mit 47 Chromosomen und einem kleinen metazentrischen Extrachromosom haben sehr wahrscheinlich eine große Anzahl verschiedener Chromosomenaberrationen, einige autosomalen und andere geschlechtschromosomalen Ursprungs.

     

Chromosomenuntersuchungen bei Kindern von Imuran®-behandelten Eltern

Summary Chromosome examination has been made of 3 children of parents, who had a renal transplantation made and were treated with Imuran. The results of the chromosome examination are shown in Table 2.Investigation of a larger number of such children is needed in order to draw any conclusion about a possible, toxic effect of Imuran^® on chromosomes.     

Kern-Plasma-Transport neusynthetisierter rRNS in Zellen einer Suspensionskultur von Petroselinum sativum

Summary A rapidly labelled rRNA precursor can be detected in callus cells of Petroselinum sativum grown on a liquid synthetic medium. Its molecular weight has been calculated to be 2.3×10⁶. This value agrees with that of the rRNA precursor from other plant material. In order to follow the synthesis and processing of rRNA in time and to correlate single steps in this process with cell organelles it was necessary to obtain pure fractions of nuclei and ribosomes. The isolation method for nuclei is given in detail. The nucleic acids are separated on polyacrylamide gels of low acrylamide concentration. Pulse-chase experiments show that the rRNA precursor is split into two fragments within the nucleus: an 18S and a 25S component. The 18S RNA leaves the nucleus rapidly. It is already found quantitatively in the ribosomal fraction after 30–60 min chase. At that time the 25S RNA is still within the nucleus; it appears much later in the ribosomes. Since the increase in ribosomal label occurs simultaneously with the decrease in nuclear label, it is concluded that there is no degradation of 18S RNA within the nucleus. Apparently there are two distinct transport mechanisms with different kinetics for the two RNA components.