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991.
Summary The skin ofTetraodon steindachneri is morphologically and cytologically adapted to the habits and locomotion of the fish, as well as to its ability to expand its body into a nearly spherical shape. Negative buoyancy, which facilitates precise maneuvers near the bottom, is achieved primarily by a very thick dermis. Various special features of the skin enable it to withstand the mechanical stresses of extreme expansion and deep folding: (1) the absence of a covering such as a cuticle on the outer surface of the epidermis, (2) the lack of scales, (3) the pronounced interdigitation of the epidermal cells, (4) the cytoskeleton of the filament-containing cells, and (5) the stratum compactum of the dermis. The spines, which inT. steindachneri can be extended and retracted, are derived, like the spines of diodontidae, from the scales of other teleosts. Each spine comprises cellular and acellular components, which together produce a complicated bilaterally symmetrical structure. Movement of the spines is mainly a passive mechanical concomitant of distension of the body, though active processes cannot be ruled out. The biological significance of the spine apparatus ofT. steindachneri is discussed.Abbreviations
af
annular fold
-
amc
apical mucous cell
-
bv
blood vessel
-
bm
basal membrane
-
cf
collagen fibers
-
cfb
collagen fiber band
-
cv
central vacuole
-
d
desmosome
-
de
dermis
-
ed
epidermis
-
f
tonofilaments
-
fcc
filament-containing cell
-
gc
granular cell
-
id
interdigitation
-
md
modified dermis
-
mr
microridges
-
n
nucleus
-
nf
nerve fibers
-
s
spine
-
sc
stratum compactum
-
sk
skeleton of spine
-
sl
stratum laxum
-
smc
sacciform mucous cell
-
sub
subcutis
-
vc
vacuole cell 相似文献
992.
993.
Summary Both fat and glycogen are present in abundance in the larynx muscles of anurans. To clarify their role, the Musculus dilatator laryngis of the male fire-bellied toad, Bombina bombina was studied.In untreated males, the mean fat content of this larynx muscle was 14%; the muscle contained glycogen amounting to 57% of that measured in the liver tissue of the same animal. After thirteen days of continual calling activity induced by administration of a gonadotropin, the fat content fell to 6%, the glycogen to 34%. The fat content was essentially unchanged (13%) by four hours of electrical stimulation of the muscle; the glycogen content, however, had fallen to 42% after this treatment. Neither component was altered in amount by castration, the fat content being about 13% and that of glycogen, 52%. Nor did treatment with gonadotropic hormone reduce either the fat content (13%) or the amount of glycogen (59%).From these results it was concluded that fats represent a direct source of energy for the larynx muscles, which is used up gradually over long periods of calling. The glycogen in these muscles, on the other hand, is a short-term store sufficient to supply energy for only a few hours of calling activity.Supported by the Deutsche Forschungsgemeinschaft. 相似文献
994.
Prof. Dr. Helga Kirchhoff Ute Boldt Renate Rosengarten Anette Klein-Struckmeier 《Current microbiology》1987,15(1):57-60
Mycoplasma sp. nov. strain 163K, the gliding microorganism isolated from the gills of a tench (Tinca tinca L.), is capable of chemotaxis, being attracted to sugars, amino acids, and mucus. The chemotactic behavior of the organisms was microscopically investigated and documented by long-time exposure photomicrographs providing motility tracks. In diffusion-generated concentration gradients of chemoattractive substances, the random motion of the mycoplasmas was strongly biased in the direction of increasing attractant concentrations. 相似文献
995.
996.
997.
In 13 patients with allergic asthma disodium cromoglycate protected fully only two from an allergen-induced asthmatic attack.Inhalation of disodium cromoglycate did not improve lung function in five patients with long-standing chronic asthma.Previous clinical trials do not show convincing evidence that this drug improves bronchial asthma in a high percentage of cases, but it seems to help a small minority of patients. 相似文献
998.
Dr. Wolfgang Braemer Dr. Helga Braemer 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1957,40(6):529-542
Ohne ZusammenfassungDie Arbeit wurde mit Unterstützung der Deutschen Forschungsgemeinschaft durchgeführt. 相似文献
999.
Helga Kapp 《Helgoland Marine Research》1991,45(1-2):263-267
Chaetognaths mainly keep to a preferred depth range by movement and resistance achieved by body shape. Some species, for exampleSagitta lyra andS. hexaptera, developed conspicuous, voluminous, gelatinous inner parts in the lateral fins. These are considered an aid toward buoyancy,
as they compensate the increasing density caused by maturing gonads. Probably, the small size of the sexual organs ofS. enflata can also be regarded as a buoyancy adaptation.
Member of the Taxonomy Group at the Biologische Anstalt Helgoland 相似文献
1000.
Elfriede K. Pistorius Klaus Jetschmann Helga Voss Birgit Vennesland 《Biochimica et Biophysica Acta (BBA)/General Subjects》1979,585(4):630-642
The basic amino acids, L-arginine, L-lysine, L-ornithine, and to a lesser extent L-histidine, strongly stimulate the O2 uptake of cell suspensions of the blue-green alga or cyanobacterium Anacystis nidulans. In the case of L-histidine, the extra O2 consumption is associated with the formation in vivo of small amounts of HCN, particularly in an atmosphere of O2. The enzyme responsible for both the stimulated O2 uptake with the basic amino acids and the formation of HCN from histidine has been isolated and identified as an L-amino acid oxidase specific for the basic amino acids. The purification (15 000-fold) of this enzyme is described. The isolated enzyme is inhibited by o-phenanthroline, which has a similar inhibitory effect on the O2 uptake of cell suspensions with (and without) added amino acids.The basic amino acid oxidase, which is not inhibited by HCN, can be regarded as an ‘alternate’ oxidase in A. nidulans. An oxidase sensitive to HCN is apparently also operative. At high concentrations of lysine or arginine added HCN can almost double the initial rate of O2 consumption of cell suspensions. This can be attributed to the inhibition of catalase by HCN. At low concentrations of the amino acids, and with more prolonged incubation time, HCN becomes inhibitory. One interpretation could be that the HCN-sensitive terminal oxidase is also involved in the extra O2 uptake elicited by the basic amino acids, but other interpretations are possible. The extra O2 uptake elicited by histidine is almost completely inhibited by HCN, which is consistent with the finding that histidine is a relatively poor substrate for the basic amino acid oxidase. 相似文献