Occurrence of bombesin-like immunoreactivity in the brain of the cartilaginous fish,Scyliorhinus canicula

Summary The presence and distribution of bombesin-like material were investigated in the brain of the cartilaginous fishScyliorhinus canicula using conventional immunocytochemical techniques. Perikarya containing bombesin-like immunoreactivity were identified in the hypothalamus, within the magnocellular component of the preoptic nucleus. Some immunopositive elements appeared to be of cerebrospinal fluid-contacting type. Beaded immunoreactive fibers were seen crossing the ventral telencephalon and the whole hypothalamus. An important tract of fibers was found in the infundibular floor and in the median eminence, in close contact with the vascular system of the pituitary portal plexus. A moderate number of positive fibers innervated the habenular complex and the dorsal wall of the posterior tuberculum. These findings indicate that a neuropeptide strictly related to amphibian bombesin is located in specific hypothalamic neurons ofS. canicula. The distribution of the immunoreactive fibers and terminals suggests that, in fish, this peptide, may be involved in neuroendocrine and neuromodulator functions.     

Vergleichend morphologische Untersuchungen zur Jugendentwicklung vonAnser- undBranta-Arten

Zusammenfassung Die Geschwindigkeit der Gewichtszunahme beiAnser indicus ist von der Aufzucht und der Rangstellung eines Gänsekükens in seiner Geschwisterschar abhängig. Mit besserem Futterangebot (Handaufzucht) verkürzt sich die Wachstumsperiode, die Flugfähigkeit setzt früher ein. Das Endgewicht wächst mit der Ranghöhe; die Ranghöhe ist im übrigen nicht von der Höhe des Schlüpfgewichts abhängig (Abb. 2 und 3, Tab. 2).Unter identischen Aufzuchtsbedingungen (Handaufzucht) bleiben bei 8 Arten die artspezifischen Wachstumsperioden erhalten. Die Zunahme an Gewicht ist nicht gleichmäßig, die Zeitspanne größten Zuwachses ist für jede Art festgelegt. Die Lage dieser Zeitspanne in der Wachstumsperiode ist um so früher nach dem Schlüpfen je nördlicher die Art brütet, d. h. je kürzer die Vegetationsperiode ist. Mit der geographischen Breite des Brutgebietes bzw. der Dauer der Vegetationsperiode ist das relative Schlüpfgewicht negativ korreliert.Die Körperlänge (Schnabelspitze mit Schwanzspitze) bei drei Arten wird erst kurz vor dem Erreichen der Adultlänge positiv allometrisch zum Gewicht. Eine negative Allometrie ist besonders ausgeprägt beiBranta leucopsis undAnser a. anser, während das Wachstum der Körperlänge beiAnser indicus isometrisch zum Gewicht verläuft. Adult istBranta leucopsis die relativ kürzeste Gans, bezogen auf das Gewicht.Die Küken vonBranta leucopsis schlüpfen mit dem prozentual längsten Kopf und dem längsten Schnabel, bezogen jeweils auf die Adultlängen. Entsprechend bleibt das Wachstum dieser Teile (Abb. 8) negativ allometrisch bezogen auf die Körperlänge. Das Verhältnis Kopflänge zu Kopfbreite bleibt konstant während der Entwicklung. Die Läufe zeigen bei den Gänsen auch nach dem Schlüpfen noch eine positive Wachstumstendenz bezogen auf die Körperlänge. Sie erreichen vorzeitig die Adultlänge. Das vorgezogene Wachstum der Läufe und die, verglichen mit Ruder- und Tauchenten relative Reduktion der Zehen (resp. Schwimmhäute), werden als Anpassung an das Weiden an Land gedeutet.Das Flügelwachstum setzt bei allen drei Arten spät ein. Die größte relative Differenz zwischen Flügel und Lauf liegt um den 10. Tag nach dem Schlüpfen, nicht wie beim Huhn zum Zeitpunkt des Schlüpfens. Die relativ längsten Flügel (bezogen auf das Gewicht) besitzt die Streifengans. Mit den Flügelproportionen und der Größe der Flächenbelastung kann die Zugstrecke korreliert werden. Je länger sie ist, desto niedriger ist die Flächenbelastung und desto relativ länger ist der Unterarm.Auch der jeweilige Beginn der Mauser in das Jugendgefieder läßt sich zur geographischen Breite des Brutgebietes bzw. der Vegetationsperiode in Beziehung setzen: Je nördlicher die Art brütet, um so früher setzt sie ein (Tab. 4 und 5). Die Dauer der Gefiederentwicklung verkürzt sich entsprechend der Dauer der Vegetationsperiode, so daß bei der Streifengans das Gefiederwachstum beschleunigt abläuft.

---

Comparative morphological studies on the development of youngAnser- andBranta-species

Summary 1. Development of weight inAnser indicus: The increase of the goslings' weight inAnser indicus is affected by rearing conditions and by the position of the gosling in the rank order of its siblings. A ready supply of rich food (e.g. at raising by hand) shortens the period of growth and the time until the gosling is able to fly if compared to raising by the parents under natural conditions.The final weight of the gosling is positively correlated with its position in the rank order of its siblings; this position, however, is independent of the weight at hatching.2. Development of weight inAnser a. anser, Anser a. albifrons, Anser brachyrhynchus, Anser c. caerulescens, Anser cygnoides, Anser indicus, Branta c. canadensis and Branta leucopsis: Under identical rearing conditions for all species the species specific periods of development are maintained. Rate of growth varies during development, and the time of maximum growth after hatching seems to be species specific. It corresponds with the latitude of the breeding areas of the species. In northern species the maximum weight increase is earlier in the period of development than in southern species. The latitude on the other hand corresponds with the duration of the vegetation period: a high latitude results in a short period of vegetation. The period of vegetation can be correlated with the relative weight of the newly hatched goslings: the shorter the period the higher the weight.The data ofAnser indicus can be interpreted with respect to the short vegetation period in the high regions of their breeding places in Central Asia.3. Increase of body length and relative growth of parts of the body inAnser a. anser, Anser indicus andBranta leucopsis: A short time before reaching the adult stage the body length (as measured from peak of bill to end of tail) shows positive allometric growth with respect to weight. In earlier stages a strong negative allometric growth is found inBranta leucopsis andAnser a. anser, while inAnser indicus the growth is isometric. Branta leucopsis has the smallest proportion of length to body weight of the adults and is the smallest by weight of the 3 species at hatching. However, proportional to adult length it has the longest bill and head at hatching. Correspondingly these parts show negative allometric growth as compared to body length. The proportion of head length to head width is constant during development.In all three species the legs grow positive allometric related to body length and the adult stage is reached before other development is finished. This advanced growth of the legs as well as the reduction of the length of toes as compared to the data ofOxyura andAythya is interpreted as an adaption to feeding. The growth of wings starts late in all three species investigated. The largest difference between length of wings and legs was observed at the 10th day after hatching, in chickens it is found after hatching.The wings are longest inAnser indicus relative to weight. Wing proportion and wing load (in g/cm²) can be correlated with flight distance to wintering places. A small wingload and a relatively long forearm ist found in species which migrate over long distances. The start of moulting into juvenile plumage corresponds with the latitude of the breeding area. Northern species show an early beginning of moult after hatching. The duration of plumage growth is relatively short if vegetation period is short. Thus inAnser indicus the plumage growth appears to be accelerated as compared to species breeding in areas with longer periods of vegetation.

     

Dopamine Autoreceptors Modulate Dopamine Release from the Prefrontal Cortex

Electrical stimulation (at 0.3, 1, or 10 Hz, 120 pulses each) produced a calcium-dependent overflow of radioactivity from slices of the rabbit prefrontal cortex preloaded with [3H]3,4-dihydroxyphenylethylamine ([3H]DA, [3H]dopamine) in the presence of desipramine. Flat frequency-release curves were observed. Apomorphine and LY-171555 inhibited in a concentration-dependent fashion the evoked overflow of DA, an effect antagonized by haloperidol. Stimulation frequencies comparable to normal firing rates of mesocortical neurons (10 Hz) drastically reduced apomorphine-induced inhibition of DA overflow. Haloperidol produced greater facilitation of DA overflow at 10 than at 1 Hz. Nomifensine, a neuronal uptake inhibitor, enhanced DA overflow. These results indicate that mesocortical DA neurons projecting to the prefrontal cortex have release modulatory autoreceptors of the D2 subtype.     

The glucan components of the cell wall of baker''s yeast (Saccharomyces cerevisiae) considered in relation to its ultrastructure

1. Commercial pressed baker's yeast, and cell walls prepared from it, were extracted in various ways and the products examined by a number of techniques, including infrared spectroscopy and electron microscopy. 2. The glucan components of the walls cannot be extracted from intact yeast cells by 3% (w/v) sodium hydroxide at 75 degrees , but at least one-third of the glucan of cell wall preparations is dissolved under these conditions, and more will dissolve after ultrasonic treatment. 3. If intact cells are given a preliminary treatment with acid the wall glucans dissolve in dilute aqueous alkali. 4. Acid conditions as mild as sodium acetate buffer, pH5.0, for 3hr. at 75 degrees are sufficient for this preliminary treatment; the glucan then dissolves in 3% sodium hydroxide at 75 degrees leaving a very small residue, which contains chitin and about 1% of the initial glucan of the wall. Dissolution is hindered by exclusion of air, or by a preliminary reduction with sodium borohydride, suggesting that some degradation of the glucan by alkali is taking place. 5. After treatment with 0.5m-acetic acid for 24hr. at 90 degrees the glucan dissolves slowly at room temperature in 3% sodium hydroxide, or in dimethyl sulphoxide. The extraction with acetic acid removes glycogen and a predominantly beta-(1-->6)-linked glucan (not hitherto recognized as a component of baker's yeast), but none of the beta-(1-->3)-glucan, which remains water-insoluble. 6. Without treatment with acid, the glucan is not significantly soluble in dimethyl sulphoxide, but can be induced to dissolve by ultrasonic treatment. 7. These results are interpreted by postulating the presence of an enclosing membrane, composed of chitin and glucan, that when intact acts as a semipermeable membrane preventing the escape of the alkali- and dimethyl sulphoxide-soluble fraction of the glucan. Mild acid treatments damage this membrane, and ultrasonic and ballistic disintegration disrupt it. 8. Some support for this hypothesis is given by the effects of certain enzyme preparations, which have been found to render a substantial part of the glucan extractable by dimethyl sulphoxide.     

Auxin transport in roots

Summary The net uptake and movement of radioactivity by 12-mm root segments of Zea mays have been studied as a function of time at 5, 15 and 25° C. Segments were supplied with an agar donor block containing 1 M IAA-1-¹⁴C or IAA-2-¹⁴C continuously or for a limited period of time (pulse-labelling). In the latter case the original donor block was replaced either by a plain agar block or by one containing 1 M unlabelled IAA. Receiver blocks were placed at the other end of the segments.The net uptake of radioactivity from the donor block at 15° C was greater at the basal end than at the apical end of the segment. At 5 and 15° C, the net uptake from a basal donor was virtually linear with time but at 25° C the rate of net accumulation decreased after about 10 h. Decarboxylation of IAA undoubtedly occurred at 15 and 25° C when the concentration in the tissue attained a high value.An acropetally polarised movement of radioactivity into the receiver blocks occurred regardless of whether the results were based on the actual amounts of radioactivity in the receiver block, or on the amounts in the receiver block expressed as a percentage of the net total radioactivity accumulated from the donor block. Only one radioactive substance was present in the receiver block and it ran to the same R_f as IAA in the isopropanol: ammonium: water solvent system.The amounts of radioactivity moving into that part of the root segment at least 6 mm distant from the end in contact with either an apical or a basal donor block were assessed. An acropetal polarity in the movement of radioactivity was observed on the basis of the actual amounts of radioactivity in these distal parts of the segments, but no such polarity was evident when the amounts of radioactivity were expressed as a percentage of the net total accumulated from the donor block. At least 3 radioactive substances were present in the tissue in addition to the substance running to the same R_f as IAA. The distribution of radioactivity in the segment cannot therefore be used to assess the distribution of IAA.Acropetal movement of radioactivity into an apical receiver block is not dependent upon the continued uptake of IAA at the basal end of the segment. No distinct pulses of radioactivity were detected moving through the root segments.Only a small part of the radioactivity in the root segment appears to be located in the polar transport system, while the bulk is not. The polarity found in the movement of the bulk radioactivity within the segment seems to be related to the polarity in IAA uptake from the donor blocks.     

Cytoplasmic Structures Associated with an Arbovirus Infection: Loci of Viral Ribonucleic Acid Synthesis

Unique cytoplasmic structures, herein designated as type I cytopathic vacuoles (CPV-I), are found in chick embryo cells early in the logarithmic phase of Semliki Forest virus replication. High resolution autoradiography demonstrated that the CPV-I are loci of (3)H-uridine incorporation. This evidence correlates well with previous biochemical data and electron microscopy of the subcellular fractions active in Semliki Forest virus ribonucleic acid synthesis. Origin of the CPV-I within host cell cytoplasm is confirmed by the distribution of electron-dense tracer particles and sequential ultrastructural observations.     

The Use of Ferritin Labelled Antibodies in the Location of Spore and Vegetative Antigens of Bacillus cereus

S ummary . Ferritin labelled antibodies have been used to detect the presence of vegetative antigens in spores. The specificity of the labelled antibodies was demonstrated. Vegetative antigens were found along the core or cortical membrane in spore disintegrates, and after germination along the developing vegetative cell wall. The implications of these results are discussed in relation to morphological studies of ultra-thin sections.