Allometric relations of total volumes of prolactin cells and corticotropic cells to body length in the annual cyprinodont Cynolebias whitei: effects of environmental salinity,stress and ageing

Summary An analysis of the allometric relations of the total volumes occupied by prolactin (PRL) and corticotropic (ACTH) cells (PRL volume and ACTH volume, respectively) to body length and a study of the immunocytochemical staining intensity of PRL and ACTH cells were used to determine the differences in activity of PRL and ACTH cells in freshwater-reared and in saltwater-reared Cynolebias whitei during the entire lifespan of this annual cyprinodont fish. An inflection in the allometric relation of PRL volume to body length was observed in fish of one-week old. The relatively large PRL volume in younger fish may be related to PRL cell activity before hatching. No inflections were observed in the allometric relations of PRL volume and ACTH volume to body length at the onset of maturation and the onset of ageing, indicating that the increased pituitary growth in maturing and ageing C. whitei is not the result of changes in PRL or ACTH cells. The slope of the allometric relation of PRL volume to body length in freshwater-reared fish was significantly steeper than the slope in saltwater-reared fish. The PRL volume in adult freshwater-reared fish was eight times larger than that in saltwater-reared fish of the same length. The intensity of immunocytochemical staining of saltwater PRL cells was significantly reduced. These volumetric and staining differences correspond to the low functional demand put upon PRL cells in saltwater-adapted fish. In contrast, the slope of the allometric relation of ACTH volume to body length and the intensity of immunocytochemical staining of ACTH cells were similar in freshwater-reared and in saltwater-reared fish. It is concluded that the functional demand put upon ACTH cells is similar in freshwater-reared and saltwater-reared C. whitei; the involvement of ACTH cells in the osmoregulation of the fish in both environments is similar.     

Adventitious shoot formation in cultures of 30-year-old Larix decidua,L. leptolepis,L. eurolepis,and L. laricina trees

Primordial shoot explants excised from buds of one Larix decidua tree, about 30 years old, produced more adventitious buds, elongating into shoots, when grown on half strength Litvay medium than when grown on other basal media. Thidiazuron and N₆-benzyladenine (BA) were equally effective in adventitious bud induction. In a comparative study of 30-year-old L. decidua, L. leptolepis, L. eurolepis, and L. laricina trees, explants from L. eurolepis and L. decidua produced a high number of cultures with adventitious buds that elongated into shoots; those from L. leptolepis were less productive, and those from L. laricina failed to form adventitious buds. The highest response was obtained with material collected in August and September, and in March and April; the lowest response occurred in explants from the October collection.     

Active Ca2+ transport in plasma membranes of branchial epithelium of the North-American eel, Anguilla rostrata LeSueur

A branchial epithelial membrane fraction, more than 20-fold enriched in Na+/K+-ATPase activity when compared with the crude homogenate of the tissue, was obtained from adult freshwater American eels. In a membrane vesicle preparation that consisted of 33% inside-out, 23% right-side-out and 44% leaky vesicles, the accumulation of 45Ca2+ was stimulated by ATP, but not by ADP. Accumulation of 45Ca2+ was prevented when vesicles were pretreated with detergent or the Ca2+ ionophore A23187; Ca2+ efflux was observed when the ionophore was added to actively 45Ca2+-loading vesicles. Oxalate did not affect Ca2+ accumulation in these vesicles. Kinetic analysis of the Ca2+-transport process by an Eadie-Hofstee plot revealed that the process is homogeneous; its kinetic parameters are a K0.5 for Ca2+ of 0.053 microM and a Vmax of 2.25 nmol Ca2+/min.mg protein (at 37 degrees C). The calmodulin dependency of this Ca2+ transporting process was shown by the inhibitory action of calmodulin antagonists and by the stimulatory effect of calmodulin repletion after EGTA treatment of the membranes. We conclude that an ATP-energized Ca2+ pump is present in the plasma membranes of branchial epithelium, that resembles the Ca2+ pumps of e.g. mammalian intestinal or renal plasma membranes, and propose its involvement in branchial Ca2+-uptake from the water.     

Ultrastructure of intestinal and gall-bladder epithelium in the teleost Gasterosteus aculeatus L., as related to their osmoregulatory function

Summary Intestinal and gall-bladder epithelial cells in sticklebacks have been examined in ultrathin sections and freeze-etch replicas. Enterocytes throughout the intestine appear to have a well-developed basal labyrinth similar to that of renal tubular cells, consisting of baso-lateral infoldings closely associated with numerous mitochondria. The lumen inside these intracellular membranes is continuous with the intercellular space via pores. Such a membrane system is also present in the epithelial cells lining the gall bladder, distinguishing them from gall-bladder cells of higher vertebrates. Morphometric analysis indicates that the basal labyrinth of enterocytes in the posterior part of the intestine increases markedly in both sexually mature males and androgen-treated females. This does not occur in the anterior part or gall bladder. In sticklebacks, androgens cause reduced urine excretion and enhanced fluid release via the anus. We conclude that the cells lining the intestine and gall bladder possess an extensive basal labyrinth that may function as a backward channel system, enabling fluid to be produced in the intestine of fish. The androgen-induced increase in the extent of the basal labyrinth in the posterior part of the intestine may be related to the enhanced rate of intestinal fluid excretion observed in sexually mature male sticklebacks.     

Transmission of Megatrypanum Trypanosomes to Cervus dama by Tabanidae1

Four fallow deer, Cervus dama, became infected with Trypanosoma (Megatrypanum) sp. by oral application of triturated guts from tabanids collected in an area with deer but without any cattle; four control calves remained negative. Upon challenge with triturated guts from tabanids from an area with pastured cattle, the four calves became infected with Trypanosoma (M.) theileri. The prepatent period in deer was five days or less. Haematopota spp. and Tabanus spp. were identified as vectors of the deer trypanosomes. It is concluded that the trypanosomes of C. dama belong to a Megatrypanum species that is not identical with T. theileri.     

Physical mapping of three fruit ripening genes：Endopolygalacturonase,ACC oxidase and ACC synthase from apple（Malus x domestica） in an apple rootstock A106（Malus sieboldii

The apple rootstock,A106(Malus sieboldii),had 17 bivalents in pollen mother cells at meiotic metaphase 1,and 17 chromosomes in a haploid pollen cell.Karyotypes were prepared from root-tip cells with 2n=34 chromosomes,Seven out of 82 karyotypes(8.5%) showed one pari of satellites at the end of the short arm of chromosome 3.C-bands were shown on 6 pairs of chromosomes 2,4,6,8,14,and 16 near the telomeric regions of short arms.Probes for three ripening-related genes from Malus x domestica:endopolygalacturonase(EPG,0.6kb),ACC oxidase(1.2kb),and ACC synthase(2kb)were hybridized in situ to metaphase chromosomes of A106.Hybridization sites for the EPG gene were observed on the long arm of chromosome 14 in 15 out of 16 replicate spreads and proximal to the centromere of chromosomes 6 and 11.For the ACC oxidase gene,hylridization sites were observed in the telomeric region of the short arm of chromosomes 5 and 11 in 87% and 81% of 16 spreads respectively,proxiaml to the centromere of chromosome 1 in 81% of the spreads,and on the long arm of chromosome 13 in 50% of the spreads. Physical mapping of three fruit ripening genes in an apple rootstock A106.Twenty five spreads were studied for the ACC synthase gene and hybridization sites were observed in the telomeric region of the short arm of chromosome 12 in 96% of the spreads.chromosomes 9 and 10 in 76% of the spreads,and chromosome 17 in 56% of the spreads.     

Plants from haploid tissue culture of Lavix decidua

Haploid embryogenic tissue was initiated on 1/2 LM medium supplemented with 500 mg/l glutamine, 1000 mg/l casein hydrolysate, 100 mg/l inositol, 30000 mg/l sucrose, and 0.1 mg/l 2,4-D. The embryoids matured to produce plantlets. One plant from one of the two lines survived. The chromosome complement of tissue cultures, of the needle bases from the source plant, and of the plant produced in vitro were established by squashes. DNA content was assessed by DNA microdensiometry. In vitro tissues were haploid (n = 12). The plant produced was mixoploid, with a predominance of diploid cells (2n = 24).     

Skin ultrastructure in relation to prolactin and MSH function in rainbow trout (Oncorhynchus mykiss) exposed to environmental acidification

The present study describes the effects of 14 days exposure to acidified (pH 4.0) soft water in the absence of aluminium, on the ultrastructure of the skin in rainbow trout (Oncorhynchus mykiss). Compared to control fish, there was a moderate increase in the incidence of necrosis in the filament cells of the fish exposed to pH 4.0, but since the integrity of the tissue appeared to be maintained, most of the ultrastructural changes observed may be considered to be adaptive. There was an increase in epidermal thickness, a higher frequency of electrondense vesicles in filament cells, an increase in the undulation of the basal lamina, and the penetration of the epidermis by cytoplasmatic processes of melanocytes in acid-exposed specimens. An infiltration of leucocytes into the epidermis, and the appearance of serous mucous cells, was also evident. Whether these events were under the control of prolactin and/or -MSH, was also investigated, but no indication for activation or inhibition of either prolactin or -MSH producing cells was obtained. Since a previous study (Balm and Pottinger 1993) had demonstrated that plasma cortisol levels were also identical in control and low pH treated trout throughout a 14 day experimental period, it is concluded that under conditions of environmental acidification, the integument autonomically maintains the adjustments necessary for successful acclimation, presumably via paracrine regulatory circuits.     

Evidence for the presence of calmodulin in fish mucus

Partly purified mucus collected from the skin of three species of fish contains a protein that, on sodium dodecyl sulphate/polyacrylamide gel electrophoresis, comigrates with bovine brain calmodulin and shows the same calcium-dependent shift in electrophoretic mobility as calmodulin. Fish mucus contains a heat-stable activator of cyclic nucleotide phosphodiesterase; activation is concentration dependent and sensitive to the specific calmodulin inhibitor calmidazolium (R 24571). The presence of calmodulin in fish mucus is further indicated by means of a specific radioimmunoassay. A drop in the calcium concentration of the water induces an increase in the immunoassayable calmodulin concentration of mucus, which indicates that the function of calmodulin in mucus is related to control of permeability of the skin epithelium to water and ions.     

The cytokineplast: purified, stable, and functional motile machinery from human blood polymorphonuclear leukocytes

We examined the formation of motile, chemotactically active, anucleate fragments from human blood polymorphonuclear leukocytes (PMN, granulocytes), induced by the brief application of heat. These granule-poor fragments are former protopods (leading fronts, lamellipodia) that become uncoupled from the main body of the cell and leave it, at first with a connecting filament that breaks and seals itself. The usual random orientation of such filaments can be controlled by preorientation of cells in a gradient of the chemotactic peptide, N-formylmethionylleucylphenylalanine (F-Met-Leu-Phe) (2x10(-9) M- 1x10(-8)). Cytochalsin B, 2.5-5 μg/ml, prevents fragment formation; colchicine, 10(-5) M, does not. In scanning electron micrographs, fragments are ruffled and the cell body rounded up and rather smooth. In transmission electron micrographs, fragments contain microfilaments but lack centrioles and microtubules. Like intact cells, both bound and free fragments can respond chemotactically to an erythrocyte destroyed by laser microirradiation (necrotaxis); the free, anucleate fragments may do so repeatedly, even after having been held overnight at ambient temperatures. We propse the name cytokineplast for the result of this self-purification of motile apparatus. The exodus of the motile machinery from the granulocyte requires anchoring of the bulk of the cell to glass and uncoupling, which may involve heat-induced dysfunction of the centrosome. In ultrastructural studies of the centrosomal region after heat, centriolar structure remains intact, but pericentriolar osmiophilic material appears condensed, and microtubules are sparse. These changes are found in all three blood cell types examined: PMN, eosinophil, and monocyte. Of these, the first two make fragments under our conditions; the more sluggish monocyte does not. Uncoupling is further linked to centrosomal dysfunction by the observation that colchicines-treated granulocytes (10(-5)M, to destroy the centrosome’s efferent arm) make fragments after less heat than controls. If motive force and orientation are specified mainly from the organelle-excluding leading front, then endoplasmic streaming in PMN is a catch-up phenomenon, and microtubules do not provide the vector of locomotion but rather stabilize and orient the “baggage” (nucleus, granuloplasm)—i.e., they prevent fishtailing. Moreover, constraints emanating from the centrosome may now be extended to include, maintenance of the motile machinery as an integral part of the cell.