New and interesting Myxomycetes from Norway

Forty–nine species of myxomycetes are reported as new to Norway. Of these, 22 species are new to Scandinavia. Several have not, or only rarely, been reported from Europe. Two species (viz. Diderma subfloriformis and Comatricha anomala) were previously known only from their type localities. Brief discussions are given for some of the more interesting species.     

Biological activity assessment of the 26,23-lactones of 1,25-dihydroxyvitamin D3 and 25-hydroxyvitamin D3 and their binding properties to chick intestinal receptor and plasma vitamin D binding protein

The binding of the natural and unnatural diastereoisomers 25-hydroxyvitamin D3-26,23-lactone and 1,25 dihydroxyvitamin D3-26,23-lactone to the vitamin D-binding protein (DBP) and 1,25 dihydroxyvitamin D3 [1,25(OH)2D3] chick intestinal receptor have been investigated. Also, the biological activities, under in vivo conditions, of these compounds, in terms of intestinal calcium absorption (ICA) and bone calcium mobilization (BCM), in the chick are reported. The presence of the lactone ring in the C23-C26 position of the seco-steroid side chain increased two to three times the ability of both 25(OH)D3 and 1,25(OH)2D3 to displace 25(OH)[3H]D3 from the D-binding protein; however, the DBP could not distinguish between the various diastereoisomers. In contrast, the unnatural form (23R,25S) of the 25-hydroxy-lactone was found to be 10-fold more potent than the natural form, and the unnatural (23R,25S)1,25(OH)2D3-26,23-lactone three times more potent than the natural 1,25-dihydroxy-lactone in displacing 1,25(OH)2[3H]D3 from its intestinal receptor. While studying the biological activity of these lactone compounds, it was found that the natural form of the 25-hydroxy-lactone increased the intestinal calcium absorption 48 h after injection (16.25 nmol), while bone calcium mobilization was decreased by the same dose of the 25-hydroxy-lactone. The 1,25-dihydroxyvitamin D3-26,23-lactone in both its natural and unnatural forms was found to be active in stimulating ICA and BCM. These results suggest that the 25-hydroxy-lactone has some biological activity in the chick and that 1,25(OH)2D3-26,23-lactone can mediate ICA and BCM biological responses, probably through an interaction with 1,25-(OH)2D3 specific receptors in these target tissues.     

Demonstration of cytoplasmic receptors for the molting hormones in crayfish

Summary From in vitro experiments using different binding assays it is in crayfish demonstrated that the cytosol of target tissues is able to bind both ecdysone and ecdysterone. The ability to bind ecdysteroids is destroyed by heating and by treatment with -chymotrypsin and N-ethyl-maleinimide (NEM) (Figs. 4, 5). In target tissues there is a strong positive correlation between protein content and binding (Fig. 6). The association of the hormone-protein-complex is rapid, taking only a few min even at 5° C (Fig. 3). The binding of the two hormones to the cytosol is both specific and saturable. The association constants for the cytoplasmic receptors from hypodermis, hindgut and midgut gland are in the range of 3–6×10⁷ M^–1 for ecdysone and 5–7×10⁸ M^–1 for ecdysterone (Fig. 8). The data suggest the existence of cytoplasmic ecdysteroid receptors.     

Epidermal and seed surface characters of plants: systematic applicability and some evolutionary aspects

Based on SEM examinations of about 5000 species of seed plants, this is a survey of their epidermal surface characters with an aim to application in taxonomy. Surface characters may be grouped into four categories: (1) Cellular arrangement or cellular pattern. (2) Shape of cells (the "primary sculpture" of a surface). (3) Relief of outer cell walls (the "secondary sculpture" superimposed on the primary sculpture), caused mainly by cuticular striations and superficially visible wall inclusions and wall thickenings. (4) Epicuticular secretions (the "tertiary sculpture" superimposed on the secondary sculpture), i.e. mainly waxes and related substances.
The systematic applicability is discussed for each of these structural groups. Epidermal characters are only slightly influenced by environmental conditions. Their high structural diversity provides most valuable criteria for the classification between species and family level. There is also some evidence for their systematic applicability above the family level.
The possible evolutionary–ecological significance of surface sculpturing is discussed briefly. There is evidence that these features may be seen primarily under the aspects of reduced ability of plants to contaminate and as temperature control mechanisms of the surfaces.     

Demonstration of five major glycoproteins in myelin and myelin subfractions.

Myelin was found to contain five major glycoproteins with molecular weights of 120000, 95000, 88000, 43000 and 38000. Light myelin contained only 5-7% of the amount of these glycoproteins in whole myelin, whereas heavy myelin and the membrane fraction contained amounts nearly identical with whole myelin. Since all the major and minor glycoproteins, with the exception of 120000-mol-wt. glycoprotein, were detected only after treating the myelin membrane with neuraminidase, N-acetylneuraminic acid is a terminal sugar residue in these glycoproteins.     

The transition of the thick ascending limb of Henle's loop into the distal convoluted tubule in the nephron of the rat kidney

Summary Examination of serial semithin sections of rat kidney cortex and a subsequent electron microscopic study of selected areas revealed that the characteristic epithelium of the cortical part of the thick ascending limb of Henle extends for a varying distance beyond the macula densa. The transition from the relatively thin epithelium of the thick ascending limb at this site to the three -or even four-fold thicker epithelium of the convoluted part of the distal tubule is sharply defined and occurs without the interposition of an intermediate cell type.The position of the macula densa at the end but still clearly within the ascending limb of Henle's loop is functionally interpreted to guarantee the separation of the sensor point macula densa from disturbing influences which might arise from the secretory activity of the subsequent tubular portion.Investigations supported by the Deutsche Forschungsgemeinschaft. The skillful technical assistance of Mrs. Saliha Sabanovic is gratefully acknowledged