Decreases in Plasma Aβ1-40 Levels with Aging in Non-Demented Elderly with ApoE-ε4 Allele

This report examines plasma amyloid proteins A40 and A42 and apolipoprotein E (apoE) levels and their relationships with age in non-demented older adults with (N = 32) or without the apoE-4 allele (N = 94). A levels did not differ between the groups whereas the 4 allele was associated with a significant reduction in plasma apoE. In subjects with the 4 allele, increasing age was associated with significant reduction in plasma A40. Subjects without the 4 allele showed a significant positive correlation between A40 and A42 levels. There was also a significant correlation between plasma A40 and apoE levels in all subjects.     

Consequences of harvesting for genetic diversity in American ginseng (<Emphasis Type="Italic">Panax quinquefolius</Emphasis> L.): a simulation study

American ginseng, Panax quinquefolius L., is one of the most heavily traded medicinal plants in North America. The effect of harvest on genetic diversity in ginseng was measured with a single generation culling simulation program. Culling scenarios included random harvest at varying levels, legal limit random harvest and legal limit mature plant harvest. The legal limit was determined by the proportion of legally harvestable plants per population (% mature plants per population). Random harvest at varying levels resulted in significant loss of genetic diversity, especially allelic richness. Relative to initial levels, average within-population genetic diversity (H _e) was significantly lower when plants were culled randomly at the legal limit (Mann–Whitney U=430, p<0.001) or when only mature plants were culled (Mann–Whitney U=394, p<0.01). Within-population genetic diversity was significantly higher with legal limit mature plant harvest (H _e=0.068) than when plants were culled randomly at the legal limit (H _e=0.064; U=202, p<0.01). Based on these simulations of harvest over one generation, we recommend that harvesting fewer than the proportion of mature plants could reduce the negative genetic effects of harvest on ginseng populations.     

Mechanism of gene conversion in Ascobolus immersus. II. The relationships between the genetic alterations in b 1 or b 2 mutants and their conversion spectrum

Summary In order to establish a relationship between the type of genetic alteration occurring in the mutant and the conversion spectrum which is associated with it, an attempt was made to characterize the genetic alterations in a sample of five spore colour mutants by specific reversion.All the mutants revert by back-mutation. Reversion of one of them is possible by mutation in external suppressor gene: at least two of the external suppressors behave like super-suppressors. Reversion of two other mutants by intragenic second-site mutation and study of the intragenic suppressors indicate that they are of the frameshift type. One of the frameshift mutants (ICR₁₇₀ induced) reverts by two alkylating agents suggesting that it originates from base(s) addition. The inhability of ICR₁₇₀ to induce reversion of this mutant suggests the preferential occurrence of base addition in ICR₁₇₀ mutagenesis. Conversly the other frameshift mutant (induced by ethyl methanesulfonate) reverts strongly by ICR₁₇₀. Thus it is concluded that it originates from deletion.These two frameshift mutants and all the ICR₁₇₀ induced mutants give no or very few asci with postmeiotic segregation and either an excess of conversion towards the mutant type allele (addition type mutant) or towards the wild type allele (deletion type mutant).Evidence supports the hypothesis that mutants which give many asci with postmeiotic segregation originate from substitution.These data imply differential recognition of non-pairing and mispairing of bases and in the case of non-pairing, that the direction of conversion is determined by the non-pairing itself.     

A comparison of male and female recombination frequency in wheat using RFLP maps of homoeologous group 6 and 7 chromosomes

A novel approach was used to compare male and female recombination rates in wheat. Doubled haploid lines were developed from an F₁ using two distinct approaches: the anther-culture technique and the Hordeum bulbosum system, from which sets of lines were developed from male and female meioses, respectively. The genotype of the lines was established at RFLP and isozyme markers polymorphic on chromosomes of homoeologous groups 6 and 7, and male and female linkage maps were calculated using this information. The markers in one segment of chromosome 6B exhibited disturbed segregation frequencies in the anther-culture population. The male and female maps differed significantly in recombination frequency between some markers on two chromosomes, and these were consistent in direction within chromosomes and inconsistent in direction between chromosomes. In two of the four chromosomes studied the male map was much longer than the female map. These results suggest that significant differences may exist in male and female recombination frequencies in bread wheat which are specific to certain chromosomal segments but are inconsistent in direction between chromosomes. Other factors, such as environmental influences, may also be important in creating differences.     

Feedback regulation of RNA polymerase subunit synthesis after the conditional overproduction of RNA polymerase in Escherichia coli

Summary The and subunit of RNA polymerase are thought to be controlled by a translational feedback mechanism regulated by the concentration of RNA polymerase holoenzyme. To study this regulation in vivo, an inducible RNA polymerase overproduction system was developed. This system utilizes plasmids from two incompatibility groups that carry RNA polymerase subunit genes under lac promoter/operator control. When the structural genes encoding the components of core RNA polymerase (, and ) or holoenzyme (, , and ⁷⁰) are present on the plasmids, induction of the lac promoter results in a two fold increase in the concentration of functional RNA polymerase. The induction of RNA polymerase overproduction is characterized by an initial large burst of synthesis followed by a gradual decrease as the concentration of RNA polymerase increases. Overproduction of RNA polymerase in a strain carrying an electrophoretic mobility mutation in the rpoB gene results in the specific repression of synthesis off the chromosome. These results indicate that RNA polymerase feedback regulation controls synthesis in vivo.     

Molecular analysis of the inheritance of the S-5 locus,conferring wide compatibility in Indica/Japonica hybrids of rice (O. sativa L.)

RFLP analysis was conducted on a population derived from a three-way cross to determine the location of the hybrid sterility locus, S-5, in relation to mapped molecular markers and to identify markers that would be useful for selection in breeding. S-5 is of interest to rice breeders because it is associated with spikelet sterility of F₁ hybrids in Indica/Japonica crosses. Identification of an S-5 allele which confers fertility in Indica/Japonica hybrids when introgressed into either the Indica or the Japonica parent has been reported. Varieties carrying this S-5 ⁿ allele are known as wide compatibility varieties (WCV). Our data suggests that RFLP marker RG213 on chromosome 6 is closely linked to the S-5 locus and can be efficiently used to identify wide compatibility (WC) lines. RG213 is a single-copy genomic clone that detects three bands of different molecular weights in DNA from Japonica (Akihikari) and Indica (IR36) varieties and WC line (Nekken 2). We demonstrate that the three alleles detected by this marker could be used to trace the inheritance of the wide compatible phenotype in breeders' material.     

Does “ring syndrome” exist? An analysis of 207 case reports on patients with a ring autosome

Summary Analysis of 207 case reports on patients with ring autosome showed that: (1) Forty patients, a fifth of the total, had extreme growth failure together with an otherwise almost-normal appearance, viz. no major malformation, no specific deletion syndrome, no or only a few unspecific minor anomalies. This phenotype may be regarded as the ring syndrome, a term proposed by Cote et al. (1981) since it is independent of what chromosome is involved. (2) Severe growth failure, the sole major physical abnormality in the ring syndrome, was seen significantly more often among patients with ring of larger chromosomes than among patients with a smaller ring, indicating that the greater the chromosome involved in ring formation, the higher is the probability of severe growth failure. (3) Larger ring chromosomes showed significantly more often instability than smaller rings, suggesting that there may be a correlation between ring instability and the size of the chromosome involved. (4) Growth failure was present in significantly more patients with a labile ring than with a stable ring, indicating that a correlation may exist between ring instability and growth failure. It is suggested that the ring syndrome observed in many cases with ring autosome may result from end-to-end fusion of chromosome ends, an event not involving deletion in the genetic sense. It is also suggested that the ring syndrome is caused by a continuous generation of secondary aneuploid cells with increased mortality, i.e. structural ring instability which seems to be a function of the size of the chromosome involved. Thus, formation of a ring chromosome in certain cases might be regarded as a structural mutation, i.e. an alteration in the structure of the genetic material per se, rather than a loss or gain of genetic dosages.     

Factors affecting facultative polygyny and breeding results in the Great Reed Warbler (Acrocephalus arundinaceus)

Summary In a population of Great Reed Warbler (42–53 stationary males) the sex ratio was balanced and occurence of polygynous males (on average 15 % of the males) was more or less compensated by respective number of unmated males. Prospective polygynists arrived earlier in spring on average than monogamists, and got the first female quicker. Their territories were larger (statistically insignificant) and more often situated close to good foraging grounds. The reeds around primary female nests were on average thicker (and taller) and not so dense as in the case of monogamous, secondary and tertiary females. The intensity of nestling feeding (no. of visits per nestling per hour) was higher in the nests of monogamous females, than in primary females, and lowest in secondary and tertiary females nests. Nestlings in secondary and tertiary female broods were on average lighter than in monogamous and primary female broods. The male helped feed nestlings in secondary female nest only exceptionally. In monogamous situation their share in feeding was ca. 50%, and less so in primary female nests. Production of fledglings per female was highest in primary females and lowest in secondary and tertiary females, mainly due to the high starvation rate in the nests of secondary and tertiary females. Generally, collected data strongly suggest that female choice is determined by territory quality, and polygyny threshold hypothesis cannot be rejected. The deception hypothesis cannot be rejected as well in some observed special situations (disruptive territories or polyterritoriality; four cases).

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Voraussetzungen für fakultative Polygynie beim Drosselrohrsänger (Acrocephalus arundinaceus)

Zusammenfassung Das Geschlechterverhältnis in der untersuchten Drosselrohrsänger-Population von 42 bis 53 war ausgeglichen. Das Auftreten polygyner (durchschnittlich 15 % der ) wurde mehr oder weniger durch eine entsprechende Anzahl unverpaarter kompensiert. Prospektiv polygyne kamen durchschnittlich früher an als monogame und waren schneller verpaart. Ihre Reviere waren (statistisch nicht signifikant) größer und lagen näher zu günstigen Nahrungsgebieten. Das Schilf in der Nähe der Nester von Erst- war durchschnittlich dicker (und höher) als und nicht so dicht wie bei Einzel- oder Zweit- und Dritt- . Die Fütterungsfrequenz der Nestlinge (Anzahl der Besuche beider Altvögel mit Futter pro Nestling pro Stunde) war bei Nestern von Einzel- höher als bei Erst- und am niedrigsten bei Nestern von Zweit- und Dritt-. Nestlinge von Zweit- und Dritt- waren durchschnittlich leichter als solche von Einzel-und Erst- . halfen nur ausnahmsweise bei der Fütterung von Nestlingen von Zweit- . Bei monogamen Paaren beteiligten sich die ungefähr zur Hälfte an der Fütterung der Nestlinge, bei Nestern von Erst- in geringerem Umfang. Der Ausfliegeerfolg war am höchsten beim Erst- und am niedrigsten bei Zweit- und Dritt- , hauptsächlich bedingt durch Verhungern der Nestlinge. Allgemein legen die Daten nahe, da\ die die nach der Revierqualität auswählen und daß das Polygynieschwellenmodell vonOrians undVerner nicht abgelehnt werden kann. Einige Beobachtungen stützen die Hypothese, daß in bestimmten Situationen (unübersichtliche Reviere, Polyterritorialität) durch Täuschung polygyn werden.

     

Zur Paarbildung der Uferschwalbe (Riparia riparia)

Zusammenfassung Uferschwalben kehren aus den afrikanischen Winterquartieren in Trupps beiderlei Geschlechts zurück. Erste Beringungsergebnisse belegen, daß zunächst mehrjährige, vermutlich untereinander bekannte Vögel eintreffen, die den Brutplatz aus vergangenen Brutperioden her kennen. Die Masse der später ankommenden Vögel dürfte weitgehend aus einjährigen oder ortsfremden Uferschwalben bestehen, die sich größtenteils erst während der Paarbildung persönlich kennenlernen. Der anfängliche Schwarmzusammenhalt der nacheinander eintreffenden Trupps führt zur Bildung von Subkolonien, die für Brutplätze ab einer bestimmten Größenordnung typisch sind. Uferschwalben- gründen nacheinander mehrere Reviere, d. h. sie besetzen Steilwandbereiche, in denen sie ausschließlich mit den Füßen eine Röhre oder Mulde graben, singen und Bogenflüge starten. Bis auf singende oder bekannte werden Artgenossen im Revier geduldet. Uferschwalben- suchen besetzte Reviere auf. Ohne Röhrenbindung verhalten sie sich still und unauffällig, ihre Grabungsaktivitäten sind von untergeordneter Bedeutung. Die Bindung an ein bestimmtes Revier entwickelt sich individuell verschieden und entscheidet über den Abschluß des Röhrenbaues (Herstellung der Nistkammer). Reviere ohne dauerhafte -Bindung werden von den aufgegeben. Aktivitäten, die auf wachsende Revierbindung eines hindeuten, sind: häufige oder/und länger dauernde Aufenthalte des in einem besetzten Revier und sporadisches Mitgraben; aggressives Verhalten gegenüber Artgenossen (i. d. R. fremde ), die im Revier landen wollen; gemeinschaftlicher, leiser Gesang von und im Röhrenbereich. Aktivitäten, die für eine vollzogene Paarbildung sprechen, sind: Fertigstellen der Röhre durch Grabung der Nestkammer; längere gemeinsame Aufenthalte innerhalb und außerhalb der Röhre; Voranfliegen des beim Röhrenanflug; Übernachten von und in der Röhre; Nestbau; ausdauernde Verfolgungsflüge während der Kopulationsphase. Die Paarbildung ist demnach ein individueller Prozeß, bei dem die Aktivitäten der im Revier als Werbung, die der als Revierwahl interpretiert werden.

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On pair-formation in the Sand Martin,Riparia riparia

Summary European Sand Martins arrive at their breeding sites in flocks of usually unmated and . Ringing results of a large population in NW-Germany and own observations indicate that the first flocks about a dozen individuals with an approximately balanced sex ratio appear at traditional breeding places and consist of older, experienced resident birds (presumably acquainted with one another). The birds arriving over the next several weeks are mainly first-year or non-resident individuals. The flocks arrive separately in areas with suitable sandcliffs, synchronize the pair-formation activities and avoid disturbances among paired and unpaired birds. This behaviour causes the formation of subcolonies, which are typical for all densely occupied breeding places. Each settles on a fixed area on the sandcliff (territory) in order to excavate a burrow, to sing the territory-song (fig. 2 b) and to perfor the territory-circle-flight (fig. 2 c, 4 a). Silent birds (normally ) are welcomed or tolerated by the resident . The sexes are monomorphic and therefore courtship displays of the are non-aggressive until establishment of pair-bonds. Only intruding singing or individually known neighbouring are driven away, usually at early stages of territory occupation. Unmated are normally shy and very sensitive to protracted disturbances. visit several occupied territories of the colony (fig. 1–3) in order to choose a burrow. leave territories which do not attract a . They settle new territories on the sandcliff, causing a surplus of burrows compared to breeding pairs in the colony. Activities which indicate the development of pair-bonds are: regular visits of a to a particular occupied territory with sporadic excavations by the ; aggressive activities of the towards other visitors usually , but sometimes at first even against the resident (i. e.: vocal threats, bill-gaping, pecking or pushing with the bill or vigorous face-to-face fights, fig. 3 b, 3 c). and sing the soft mating song at or in the burrow (fig. 1 c). Activities which indicate completed pair-bonds are: completion of the burrow by digging the nestchamber, predominantly done by the ; both birds staying together over long periods, both inside and outside the burrow; invitation-flight by the (fig. 4 b); and spending the night together in the burrow; beginning of nest-building, first only by the , then by both birds and finally only by the , accompanied by the (guarding-flight;, fig. 4c); mate-pursuit flights (sexual chases) during copulation phase, in which the singing pursues the silent , often accompanied by other (cp. fig. 4 d). Pair-formation in the Sand Martin occurs on individual territories and not, according toHickling (1959), within the flock.

     

Molecular switch of F0F1-ATP synthase,G-protein,and other ATP-driven enzymes

Exchange-out of amide tritium from labeled -subunit of ₃₃ complex of F₀F₁-ATP synthase was not accelerated by ATP, suggesting that hemagglutinin-type transition of coiled-coil structure did not occur in -subunit. Local topology of nucleotide binding site and switch II region of G-protein resemble those of F₁- subunit and other proteins which catalyze ATP-triggered reactions. Probably, binding of nucleotide to F₀F₁-ATP synthase induces conformational change of the switch II-like region with transforming subunit structure from open to closed form and this transformation results in loss of hydrogen bonds with the subunit, thus enabling the subunit to move.     

A marked drop in the incidence of the null allele of the B gene of the fourth component of complement (C4B*Q0) in elderly subjects: C4B*Q0 as a probable negative selection factor for survival

Summary The incidence of allotypes of the genes of the fourth component (C4) and factor B of the complement system was compared in 252 persons under 45 years of fage (young group) with 482 people between 61 and 90 years of age (old group). One hundred people older than 90 years of age (nonagenarians) were also investigated. A striking difference was found between the young and old groups in the incidence (16.1% and 5.4%, respectively) of a silent gene of the C4B allele (C4BQ0). This difference was even more marked among young and old men (17.6% vs 3.4%). The incidence of the C4BQ0 allele in women dropped to the level of the men only in the nonagenarian group. The most probable explanation for this finding is that people carrying the C4BQO allele die from as yet unidentified disease(s) in their middle-age. Therefore, male (and to a lesser extent female) carriers of this allele may have a considerably shorter life expectancy than individuals without a silent gene in the C4B locus.     

The inheritance of radiation induced semi-sterility in Rhodnius prolixus

Eggs from crosses of 40 adult male R. prolixus irradiated with 6K rad -rays with normal females had a mean fertility of 23.9%, only 2 crosses being completely sterile. The 86 F₁ progeny of both sexes, when outcrossed with normal mates, had a mean egg fertility of 12.6%, and 43 of these matings were completely sterile. Twenty-eight F₂ bugs reared from F₁ x normal crosses were mated with normal partners and had a mean fertility of 44.6%, 6 of them being fully fertile, a reversal towards normal fertility. Cytogenetic examination of F₁ F₂ and F₃ males showed that these changes in fertility correlated well with the degree of chromosomal abnormality found. The very high recovery rate of translocations in F₁ generation males can be related to the holocentric chromosomes of these bugs which precludes the formation of dicentric chromosomes which are inviable in monocentric species. In F₁ and F₂ males the majority of translocations were associated as chains of III+I or as chains of IV. Only one bug was found with a ring of IV chromosome association and it is suggested that chromosome morphology, combined with a low chiasma frequency, favours chain association. Most chain multivalents showed linear orientation which may lead to duplication deficiencies and zygotic death. However parallel, indifferent and the more stable convergent modes of chain orientation were also all observed indicating that survival of some translocations in this species may be possible. The survival to the F₂ generation of chromosomal fragments confirmed the holocentric nature of triatomine chromosomes. It is suggested that semi-sterile males would prove more effective than releases of completely sterile males for reducing wild populations of R. prolixus, because of the delayed effects of sterilizing radiation consequent upon the holocentric structure of triatomine chromosomes.     

Translocation t(7p+; 13q-) associated with recurrent abortion

Summary A balanced translocation was found in a normal female with a history of four abortions. On the basis of the Giemsa-banding pattern the abnormality was interpreted as to be a translocation of a part of the long arm of chromosome 13 to the short arm of chromosome 7:t(7;13)(7qter7p22::13q1413qter;13q1413pter::7p227pter). Problems in genetic counseling are discussed with respect to this case.Supported by the Forschungsprojekt Medizinische und soziale Probleme der menschlichen Reproduktion des Ministeriums für Gesundheitswesen der DDR.     

Über die biologie blutsaugender simuliiden (diptera)

Summary Swarming behaviour of the mammalophilic simuliids Wilhelmia equina, W. salopiensis and Boophthora erythrocephala is closely related to sex-finding. Long-range orientation occurs by optically directed swarming of the towards a dark marker above them contrasting with the bright sky. flying directly to the same marker or the bigger object carrying it, e.g. a tree, are visually recognized by the at a short distance (short-range orientation).Sex-orientation shows the following pattern of behaviour: Weather conditions (temperature, relative humidity, covering of the skyfree, partially or covered) may vary to a great extent without obvious effect. If brightness of the sky exceeds 5000 lux and velocity of the wind is limited to 10 m/sec measured 1 m above the ground, and begin to seek for moving (e.g. blood hosts of , adequate dummies) or motionless conspicuous objects (e.g. trees, cottages).Around these objects behaviour differs between species, but more markedly between the sexes: are flying directly to the object and sit down, are swarming in a short distance from it, waiting for the arrival of more . As the emerge from the pupae earlier than the which are not yet inseminated, they are more numerous. Furthermore, a are swarming longer than one day (demonstrated by tagging experiments) so that every may copulate several times.Orientation of towards the optic marker is the last stage in the long-range orientation. With regard to of W. equina, the pattern is as follows: The occupying the uppermost flying position in the whole swarm orientates itself in such a manner that the image of the marker is centrally in the median space of its head, which is covered by both complex eyes having an overlapping space of 38°. Even during individual movements this position is maintained so that the marker leaves this space only partially. Moreover the remains at such a distance that the image of the marker neither exceeds the anatomical field of vision of the dorsal parts of the complex eyes in the sagittal plane (54°) nor disappears from it completely. Accordingly, the vertical distance from the marker depends on its size, but at a maximum distance of 60 cms the fly changes its orientation, using a portion of the marker, such as a corner, as new fixpoint. Orientation to the marker is not restricted to the background of the open sky; other backgrounds of the same colour are accepted, too, if they are smaller than the anatomical field of vision in the median sagittal plane (54°). Furthermore, lateral parts of the same field of vision, which is 158° in the transversal plane, may be covered up to one half of its width by dark objects, whereas no object is tolerated touching the median sagittal field of vision in front. This demonstrates, too, that not visual perception as such, but the special behaviour of the simuliids is related to the anatomical field of vision.With W. salopiensis, W. equina, and B. erythrocephala meeting and recognizing of the partner for copulation usually occurs during flight. Both partners, however, fall down to the ground immediately thereafter and seperate within 3–5 seconds. In the final stage of copulation the partners are in opposite position, but the abdomina remain in normal position, i.e. turned at 180°, the , lying on its back with its abdomen not twisted. Compared with the copulation among Culicidae and Ceratopogonidae, this position must be considered more primitive.The special differentiation of the complex eyes of male simuliids permits them to recognize both distances (as indicated by the orientation to the marker) and moving objects, enabling them to distinguish between flying , which will be pursued, and in the same swarm, the presence of which causes no reaction, and enemies such as hovering flies and preying hymenoptera, the arrival of which produces a flight reaction. All these actions are realized by the coarsely screened dorsal parts of the complex eyes.The anatomical position of the male genitalia must be considered morphologically primitive, as the hypopygium lacks inversion. Transfer of sperms is by means of a spermatophore. In the female, the accessory glands of the 8th segment open into the ductus receptaculi, whereas the glands of the 9th segment open to the outside close to the gonoporus.

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Herrn Oberlehrer i. R. G. Schlörer zum 75. Geburtstag gewidmet.     

Genes of the constant regions of functional immunoglobulin heavy chain of Japanese flounder,<Emphasis Type="Italic"> Paralichthys olivaceus</Emphasis>

IgM and IgD genes of the Japanese flounder were cloned and characterized from a genomic bacterial artificial chromosome (BAC) library. The gene contained four constant region exons (C1–C4), and two transmembrane exons (TM1 and TM2), which conforms to the organizational pattern of all other vertebrate -chain genes examined so far. In the same BAC clone, the gene, which is homologous to the IgD gene in mammals and teleost fish, was found immediately (0.9 kb) downstream of the IgM gene. This gene encoded seven exons (C1–C7) and two TM exons (TM1 and TM2) and had no duplication of C1-C2, as found in Atlantic cod, or C2-C3-C4, as found in Atlantic salmon and channel catfish. Phylogenetic and sequence analyses strongly suggest that teleost is more closely related to non-IgM isotypes than IgM isotypes. The heavy chain (IgH) locus of Japanese flounder, which encodes m, s and m, was found to be fully functional.     

Restriction fragment analysis of ‘null’ forms at the Gli-1 loci of bread and durum wheats

Summary Wheat accessions lacking some of the - and -gliadin components encoded by the Gli-1 loci on the short arm of chromosome 1D in bread wheat and chromosome 1A in durum wheat were studied by two-dimensional polyacrylamide gel electrophoresis and restriction fragment analysis. Digested genomic DNAs of normal and null forms were probed with a cDNA clone related to -/-gliadins and with a genomic clone encoding an LMW subunit of glutenin. The hybridisation patterns with the -/-gliadin probe were similar to those of cvs Chinese Spring and Langdon used as standards for bread and durum wheats, respectively, but several restriction fragments located on the 1D chromosome of bread wheat and the 1A chromosome of durum wheat were absent in the null forms. In addition, specific LMW glutenin fragments encoded by the same chromosomes were also absent in the null forms, suggesting that simultaneous deletions of blocks of genes for both -/-gliadins and LMW glutenins had occurred. Comparisons of the protein and RFLP patterns enabled some proteins to be mapped to specific restriction fragments.     

Ultrastructure of four types of striated muscle fibers in the atlantic hagfish (Myxine glutinosa,L.)

Summary Four types of striated muscle fibers with distinctive ultrastructure were defined in the Atlantic hagfish (Myxine glutinosa, L.): white, intermediate, and red fibers of m. parietalis, and red fibers of m. craniovelaris.White fibers are thick, contain very few mitochondria and fat vacuoles, and possess distinct and separate myofibrils with thin Z-disks and distinct M-lines. Intermediate fibers are thinner, possess largely similar myofibrils that often are even better separated due to a higher content of fat vacuoles and especially mitochondria and glycogen granules. Red fibers of m. parietalis contain large amounts of mitochondria, fat vacuoles, and glycogen granules. Their myofibrils possess M-lines, and although branching more, the myofibrils of red fibers conform with a Fibrillenstruktur pattern like those of white and intermediate fibers. Red fibers of m. craniovelaris are very thin, possess many smaller fat vacuoles, and large amounts of mitochondria and glycogen granules. The myofibrils are significantly thinner than in m. parietalis fibers, run as quite independent well separated units, possess thicker Z-disks, and lack M-lines. Large amounts of myosatellite cells are associated with these red fibers.Triads are located near A/I-junctions in all four fiber types and occur irregularly, the density of triads being different in the various fiber types.We are indebted to Dr. Finn Walvig, Biological Station, University of Oslo, Drøbak, for supply of hagfishes, and we also wish to thank Dr. Jan K. S. Jansen, Institute of Physiology, University of Oslo, for valuable suggestions during this study.     

Synthesis of disaccharide derivatives employing β-N-acetyl- d-hexosaminidase, β-d-galactosidase and β-d-glucuronidase

-N-Acetyl-d-hexosaminidase from Aspergillus oryzae catalysed the stereo- and regiospecific formation of the 6-O-benzylated disaccharide derivatives GalNAc1-3(6- OBn)Gal-SEt and GlcNAc1-3(6-OBn)Gal-SEt, which were obtained in transglycosylation reactions employing ethyl 6- O-benzyl-1-thio--d-galactopyranoside as acceptor. Preparative amounts of the chitobiose derivative GlcNAc1- 3GlcNAc-OPhNO2-p was prepared as well. - N-Acetyl-d-hexosaminidase from bovine testes catalysed the specific synthesis of GlcNAc1-3(6-OBn)GlcNH2-SEt and GalNAc1-3(6-OBn)GlcNH2-SEt, employing ethyl 2-amino-6-O-benzyl-2-deoxy-1-thio--d-glucopyranoside as acceptor. -d-Glucuronidase from E. coli was found to catalyse the formation of GlcA1-3(6-OBn)GlcNH2- SEt employing the same acceptor.     

Non-reciprocal gonadal dysgenesis in hybrids of the chironomid midge Chironomus thummi

In male hybrids of the cross Chironomus thummi thummi (stock Hl) x Ch. th. piger (stock E) , but not the reciprocal cross, rudimentary testes develop at a growth temperature of 21 ° C. Within the dysgenic testes of these hybrids a number of abnormalities are observed which are restricted to the germ line. Approximately 60% of the hybrid males show allocyclic chromosome behaviour in spermatogonia and spermatocyte I nuclei. Within these nuclei two groups of four chromosomes are formed which differ from one another in their state of condensation. Each chromosome group consists of three long and one short chromosome. In cases where allocycly is very pronounced, the chromosomes of both groups disintegrate into numerous unequally sized fragments at meiotic prometaphase I, and gametes are not produced. In individuals, in which the allocycly is less pronounced or absent the nuclear divisions appear to be normal but chromosome and chromatid aberrations are frequent, and the number of viable sperm is reduced. In these males, the chiasma frequency is also decreased more than 12-fold in comparison with the reciprocal, unaffected piger x thummi hybrids.     

Changes in the distribution of integrins and their basement membrane ligands during development of human thyroid follicular epithelium

Interactions between cells and basement membrane components are crucial for the regulation of epithelial cell differentiation and polarization. We have studied by immunohistochemical methods the distribution of integrin adhesion proteins and some of their basement membrane ligands in foetal (16--19 weeks) and adult thyroid follicular epithelia. A diffuse immunoreactivity for only 3, v and 1 integrins was found in foetal follicular epithelium, whereas in adult follicular epithelium these integrins were expressed basally in a polarized manner. Additionally, 3 integrin was seen in a more basolaterally confined manner in adult follicular epithelium. Among basement membrane components, laminin 1, 1, 1 and 2 chains were found in epithelial basement membranes of the foetal thyroid gland, suggestive of the presence of laminins-1 and -3. In contrast, the basement membranes of adult follicular epithelium presented a much weaker immunoreactivity for the laminin 2 chain. Furthermore, immunoreactivity for the laminin 2 chain was occasionally seen in adult thyroid glands, apparently confined to myofibroblasts. Immunoreactivity for type IV collagen 1 and 2 (IV) chains was found in follicular basement membranes of foetal as well as adult thyroid gland. The results suggest that during maturation of foetal thyroid follicular epithelium a distinct polarization of integrins takes place. In mature thyroid follicular epithelium, the presumable adhesion-mediating integrin complexes are 31, v1 and/or v3 mediating adhesion to laminin-1 (1-1- 1) and type IV collagen trimer 12 (IV)