Ultrastructure of spermatids and spermatozoa in the cyclostomatous bryozoan Tubulipora (Bryozoa,Cyclostomata)

Summary Differentiation of spermatids to mature spermatozoa in the bryozoan Tubulipora liliacea was studied by transmission electron microscopy. The spermatozoon of Tubulipora is of a filiform, modified type, and has evolved from the primitive type as an adaptation to a specialized biology of fertilization. The head of the spermatozoon consists of a small, conical acrosome capping an elongated, cylindrical, anteriorly tapering nucleus. A basal invagination in the nucleus contains the proximal portion of the axoneme and a dense attachment matrix. The flagellar axoneme has the typical 9+2 structure. Four elongated rodshaped mitochondria with typical cristae surround the axoneme in the cylindrical middle piece. Granular electron-dense material is accumulated in the form of four columns alternating with four long cylindrical mitochondria. The mitochondrial middle piece is separated externally from the tail region by an involution of the plasma membrane. The tail region contains a cytoplasmic sheath with accessory fibers surrounding the axoneme. Nine outer, coarse fibers extend posteriorly paralleling the nine doublets of the axoneme. The coarse fibers develop from electron-dense plate-like structures associated with the doublets of the axoneme. A characteristic feature in spermiogenesis is that spermatozoa develop in tetrads. There seem to be significant differences in spermatozoan ultrastructure between the three bryozoan classes Stenolaemata, Gymnolaemata, and Phylactolaemata. The differences indicate different lines of evolution of fertilization biology in these groups.Abbreviations used in the figures a acrosome - av acrosomal vesicles - ax axoneme - c coarse fiber - d electron dense rod - m mitochondrion - mp middle piece - Scale bars=0.5 m - mt microtubule - n nucleus - ne nuclear envelope - p nuclear protrusion - pm plasma membrane - t tail     

Circadian placebo and ACTH effects on urinary cortisol in arthritics

The effect of placebo and ACTH-1-17 (Synchrodyn®, Hoechst) upon urinary free cortisol was examined at 5 different circadian stages on 10 men with Steinbrocker Stage II–III rheumatoid arthritis. A mean cosinor analysis of urinary cortisol data from the subjects prior to treatment with either ACTH or placebo revealed a statistically highly-significant rhythm. A circadian variation in a response of urinary free cortisol to a placebo was also seen. Moreover, the response of the midline-estimating statistic of rhythm (rhythm-adjusted circadian average) of urinary free cortisol to ACTH-1-17 by patients with rheumatoid arthritis is circadian rhythmic. This reactivity rhythm is out of phase with the spontaneous rhythm in urinary cortisol acrophases—in the tests limited thus far to midsummer. The further assessment of the circadian component in the context of broader interactions by rhythms with other frequencies in various conditions in health and disease is warranted by the demonstration of rhythms here presented for men with rheumatoid arthritis.     

Variations in the composition of bovine hip articular cartilage with distance from the articular surface.

Punch biopsies of bovine hip articular cartilage was sectioned according to depth and the proteoglycans were isolated. The mid-sections of the cartilage contained more proteoglycans than did either the superficial or the deepest portions of the cartilage proteoglycans than did either the superficial or the deepest portions of the cartilage. The most superficial 40 micrometer of the cartilage contained relatively more glucosaminoglycans compared with the remainder of the cartilage. The proteoglycans recovered from the surface 200 micrometer layer contained less chondroitin sulphate, were smaller and almost all of these molecules were able to interact with hyaluronic acid to form aggregates. From about 200 micrometer and down to 1040 micrometer from the surface, the proteoglycans became gradually somewhat smaller, probably owing to decreasing size of the chondroitin sulphate-rich region. The proportion of molecules that were able to interact with the hyaluronic acid was about 90% and remained constant with depth. The proteoglycans from the deepest layer near the cartilage-bone junction contained a large proportion of non-aggregating molecules, and the average size of the proteoglycans was somewhat larger. The alterations of proteoglycan structure observed with increasing depth of the articular cartilage beneath the surface layer (to 200 micrometer) are of the same nature as those observed with increasing age in full-thickness articular cartilage. The articular-cartilage proteoglycans were smaller and had much higher keratan sulphate and protein contents that did molecules isolated from bovine nasal or tracheal cartilage.     

Cartilage proteoglycan aggregate formation. Role of link protein.

Cartilage proteoglycan aggregate formation was studied by zonal rate centrifugation in sucrose gradients. Proteoglycan aggregates, monomers and proteins could be resolved. It was shown that the optimal proportion of hyaluronic acid for proteoglycan aggregate formation was about 1% of proteoglycan dry weight. The reaggregation of dissociated proteoglycan aggregate A1 fraction was markedly concentration-dependent and even at 9 mg/ml only about 90% of the aggregates were reformed. The lowest proportion of link protein required for maximal formation of link-stabilized proteoglycan aggregates was 1.5% of proteoglycan dry weight. It was separately shown that link protein co-sedimented with the proteoglycan monomer. By competition with isolated hyaluronic acid-binding-region fragments, a proportion of the link proteins was removed from the proteoglycan monomers, indicating that the link protein binds to the hyaluronic acid-binding region of the proteoglycan monomer.     

The carotenoids of Flavobacterium strain R1560

The main carotenoid of Flavobacterium strain R1560 has been identified as (3R,3R)-zeaxanthin. Also present were small amounts of 15-cis-phytoene, phytofluene, -carotene (7,8,7,8-tetrahydro-, -carotene plus 7,8,11,12-tetrahydro-, -carotene), neurosporene, lycopene, -zeacarotene, -carotene, -carotene, -cryptoxanthin, rubixanthin, 3-hydroxy--zeacarotene and several apo-carotenals. Zeaxanthin production was inhibited by nicotine (10 mM), and lycopene and rubixanthin accumulated. The biosynthesis of zeaxanthin is discussed in terms of pathways and also of half-molecule reaction sequences. The presence of zeaxanthin may be a characteristic of a group of Flavobacterium species, and may thus be useful in the taxonomic classification of these organisms.     

The mucus-trap hypothesis on feeding of aquatic nematodes and implications for biodegradation and sediment texture

Summary Many aquatic nematodes continuously produce with their caudal and pharyngeal glands a slimy trace consisting of sticky, elastic threads which give an acid mucopolysaccharide reaction. Along these traces small particles adhere firmly thus making the traces visible at low magnifications. By creeping repeatedly on their traces the nematodes produce burrows and solid, branched concretions in fine sediments. By these activities soft bottoms acquire a particular framework texture which perhaps may, for instance in the deep sea, enable an interstitial, non-boring microfauna to thrive.The authors suppose that the copious mucus secretion of nematodes is mainly involved in nutrition and they present an hypothesis on the assumed mode of feeding (mucus-trap hypothesis): With their mucus threads these nematodes entrap small detritus particles, bacteria, and macromolecules which subsequently are browsed together with the mucus. The combination of an adhesive mucus thread and the particular mouth construction in nematodes represents a highly elaborated collecting and sorting system for food acquisition. In addition, decomposition processes of organic material coated by the mucus may contribute to a secondary food source which is controlled by nematodes. Feces are embedded within the mucus, and their remaining nutrient content may be subjected to a later re-utilization.     

Endogene Synthese kurzlebiger Messenger-RNS in der Oocyte vonDysdercus intermedius Dist. nach Abschluß der Vitellogenese

Zusammenfassung In den Oocyten des telotroph-meroistischen Ovars vonDysdercus intermedius Dist. findet während der Endphase der Oogenese, 4–14 h vor der Eiablage, eine Synthese von nichtribosomaler RNS statt. Eine in vivo-Markierung dieser RNS läßt sich erreichen, wenn radioaktive RNS-Vorstufen einem Nucleotidpool zugeführt werden, der im Ooplasma vor der Chorionbildung angelegt wird.Diese vor der Eiablage gebildete RNS zeichnet sich durch einen hohen Turnover aus. Sie erscheint zunächst in Form einer hochmolekularen Vorstufe und wird im Verlauf weniger Stunden in kleinere, nichtribosomale Moleküle mit S-Werten zwischen 30 und 5 umgewandelt. Im frisch abgelegten Ei fehlen RNS-Spezies, die dieser endogenen Oocytensynthese entstammen; es sind nur noch ihre Degradationsprodukte, die sich innerhalb der Nucleotidfraktion ansammeln, nachweisbar. Die endogen synthetisierte RNS wird demnach im Gegensatz zu der in den Nährzellen synthetisierten und im Ei in stabiler Form gespeicherten RNS nicht für einen Bedarf während der Embryogenese konserviert.Die endogen synthetisierte RNS zeichnet sich durch einen hohen Poly (A)-Gehalt aus; 57% hybridisieren mit an Glasfaserfiltern immobilisiertem Poly(U). Wenige Stunden vor der Eiablage findet man kurzlebige oocytäre RNS-Moleküle an Polysomen assoziiert. Die Inkubation dieser Polysomen in einem in vitro-Proteinsynthese-System liefert Polypeptide, deren Auftrennung am SDS-Polyacrylamid-Gel ein charakteristisches Bandenspektrum ergibt. Die Molekulargewichte der 4 Hauptbanden liegen bei 65000, 48000, 44000, und 40000. Keines dieser Proteine ist mit einem Chorionprotein identisch.Die Kurzlebigkeit, der relativ hohe Poly (A)-Gehalt sowie die Fähigkeit, die Proteinsynthese sowohl in vivo als auch in vitro zu aktivieren, spricht dafür, daß die spät-oocytär gebildete heterogene Population von RNS-Molekülen mRNS-Komponenten enthält.Bei Frl. Heidrun Greipel bedanken wir uns für die ausgezeichnète Assistenz.     

Paarungssystem und Fortpflanzungsstrategie der Beutelmeise (Remiz p. pendulinus)

Zusammenfassung Paarungssystem und Fortpflanzungsstrategie der Beutelmeise wurde in 10 Jahren in Süddeutschland und Österreich untersucht. Der Saisonablauf für und wird in einem Schema zusammengefaßt. Die Brutpflege übernimmt i. allg. nur ein Altvogel (bei ca. 60 % aller Brutnester , bei 10 % ). Unklar ist, wie die Abstimmung erfolgt, welcher Altvogel das Gelege betreut. Offenbar herrscht eine Konfliktsituation zwischen den Geschlechtern, die sich in zahlreichen Gelegeaufgaben niederschlägt (ca. 30 % aller Brutnester). Die Verhaltensweisen betreuen bzw. verlassen sind für und nicht gleichmäßig über die Brutsaison verteilt. Die Mediane für die Betreuung durch das und die Aufgabe der Nester liegen dicht beieinander, betreuen die Nester erst wesentlich später. In Illmitz/Österreich nahm die Gelegegröße mit fortschreitender Jahreszeit ab. Die Gelegegröße der aufgegebenen Gelege war kleiner als die zeitgleich zu erwartende Gelegegröße der betreuten Gelege. Wenn das abwandert, komplettiert es das Gelege offensichtlich nicht; damit wird für das zurückbleibende erfolgreiche Brutpflege möglich. Beide Geschlechter verfolgen unterschiedliche Strategien, um einen möglichst guten Fortpflanzungserfolg zu erreichen. Beim besteht die ganze Brutsaison hindurch Bereitschaft, mehrere Nester zu bauen und möglichst viele zu haben. Gegen Ende der Brutsaison, wenn nur noch wenige brutbereite verfügbar sind, übernehmen die u. U. selbst die Brutbetreuung. betreuen zu Beginn der Brutsaison komplette Gelege selbst. Bei rund 30 % der ist aber schon zu Beginn der Brutsaison die Bereitschaft vorhanden, das Gelege mit unvollständiger Gelegegröße nicht selbst zu betreuen und die Verantwortung hierfür dem zu überlassen. Zum Geschlechterkonflikt kommt es, wenn beide Strategien hinsichtlich Abwandern kollidieren; er läßt sich mit Hilfe der Spieltheorie erklären. Wegen der großen Wanderungen während der Brutperiode haben die Angaben zum Verpaarungsstatus der einzelnen Vögel Minimalcharakter. Mindestens 25 % aller und 12 % aller waren polygam. Daß während der ganzen Brutsaison keine Partner haben, ist nachgewiesen. Der Bruterfolg polygamer war signifikant größer als der von mit nur einem Brutnest. Polygame hatten größere Flügel als die übrigen; auch deutet sich an, daß alte erfolgreicher sind als junge. Eine Polygynierate von bis zu 60 % dürfte realistisch sein; die Polyandrierate dürfte bei ca. 30 % liegen. Polyandrisches Verhalten ist aber nicht immer mit einer Steigerung der Reproduktionsrate verbunden. Besonders zu Beginn der Brutsaison bedeutet die Abwanderung des mit hoher Wahrscheinlichkeit die Aufgabe des Nestes, da die in dieser Phase die Brutbetreuung in der Regel nicht übernehmen. Einzelne waren in der Lage, nacheinander zwei Bruten alleine großzuziehen.

---

Mating system and strategy of reproduction in Penduline TitRemiz p. pendulinus

Summary From 1978 to 1987, 477 nests of the Penduline Tit were checked in Bavaria and Austria. Adult birds were marked individually with colour rings.In northern Bavaria, the major part of Penduline Tits started building nests in April and May (median date: May 10). As early as end of May a large number was leaving the breeding grounds. The population in the riverine forests of the river March/Austria basically followed the same cycle. On the other hand, birds breeding at Lake Neusiedl/Austria arrived as late as the beginning of June (median date for start of nestbuilding: June 23). A generally valid seasonal pattern for both sexes see fig. 1, 2. Penduline Tits exhibit uniparental care. Most of the nests (about 60 %) were attended by females, about 10 % by male and about 30 % were deserted, because neither the female nor the male decided to incubate (tab. 1).Early in the year, clutches were reared by the female or abandoned; preferably at the end of the breeding season males incubated. A significant relation between clutch size and season could be found at Illmitz/Austria. If average clutch size for female, male or no care are compared with the average clutch size of the respective five-day periods in which the medians of the three categories were found, a significantly smaller clutch size was apparent in abandoned nests. Due to extensive migratory behaviour during the breeding season, a calender effect of clutch size was not calculated for the Upper Main/Bavaria. However, clutch size in nests incubated by females exceeded the size of the abandoned ones. The incubation of smaller clutches by males in the same area is hard to explain. Insufficient data and/or the lack of potential mates as a consequence of early migration may account for it. If a female decides to abandon a nest she evidently leave the clutch incomplete, as if to give the male a commission to care for the young. Thereby, females economize on their reserves in order to be able to produce additional clutches with other males.To achieve optimal reproductive success both sexes follow different strategies. Males: During the whole breeding season males are able to construct a large number of nests to attract as many females as possible. At the end of the breeding season, when only few females are available, some of the males care for their broods themselves. Females: At the beginning of the breeding season, most females are ready to incubate complete clutches. But already at this time, approximately 30 % of the females desert incomplete clutches so as trying to give commission for brood care to the male.The battle of the sexes arises, if both sexes abandon the clutch. This conflict may probably be explained by the game theory. Due to the migrations during breeding season, an exact documentation of the mating status of individual birds was limited. Polygamy occured at least in 25 % of the males and 12 % of the females (tab. 4). A number of unpaired males was also evident during the whole breeding season. Polygynous males reached higher breeding success (tab. 8), and were larger (wing-length) as compared to the other males. Older males may be more successful than younger. According to the number of males leaving nests, the rate of polygyny might be up to 60 % and, due to the number of clutches abandoned by females, approx. 30 % of them are polyandrous. However, polyandrous behaviour was not linked to an increased reproduction rate. Especially at the beginning of the breeding season, most of the nests deserted by females were completely abandoned. Some females were able to raise two broods in one season.

     

Purification and substrate specificity of two cysteine proteinases of Giardia lamblia.

The proteinase activity present in homogenates of trophozoites of Giardia lamblia, active on azocasein and urea-denaturated hemoglobin, was separated into two different enzymes by a series of purification procedures. These procedures included gel filtration on Fractogel TSK HW-55 (F), organomercurial agarose affinity chromatography, and ion exchange chromatography on DEAE-cellulose. By chromatography on Sephadex G-100, two purified enzymes exhibited relative molecular weights of Mr = 95,000 and 35,000 +/- 10%, respectively. On the basis of inhibition by thiol reagents and abrogation of this effect by dithiothreitol and cysteine, they were identified as cysteine proteinases. Proteinase I (Mr = 95,000) and proteinase II (Mr = 35,000) were active against the beta-chain of insulin releasing characteristic fragments. However, differences in substrate specificities of the two enzymes could be observed by using synthetic peptides that represent sequences 1-6, 8-18, and 20-30 of the insulin beta-chain. Furthermore, the synthetic tetrapeptides Arg-Gly-Phe-Phe, Arg-Gly-Leu-Hyp, and Arg-Arg-Phe-Phe were hydrolyzed by the two proteinases releasing Phe-Phe and Leu-Hyp, respectively. Compared with Arg-Gly-Phe-Phe, the rates of hydrolysis of Arg-Gly-Leu-Hyp and Arg-Arg-Phe-Phe at substrate concentrations of 1 mM were 91% and 63% (proteinase I) and 80% and 57% (proteinase II), respectively.