Phylogenetic study of the oxytocin-like immunoreactive system in invertebrates

1. A phylogenetic study of oxytocin (OXT)-like immunoreactive cells was performed by the PAP method in the central nervous system of invertebrates. 2. The immunoreactivity was detected in the nerve cells of Hydra magnipapillata of the Coelenterata; Neanthes japonica and Pheretima communissima of the Annelida; Oncidium verrucosum, Limax marginatus and Meretrix lamarckii of the Mollusca; and Baratha brassica of the Arthropoda. 3. No immunoreactive cells were found in Bipalium sp. of the Platyhelminthes; Pomacea canaliculata, Aplysia kurodai, Bradybaena similaris and Achatina fulica of the Mollusca; and Gnorimosphaeroma rayi, Procambarus clarkii, Hemigrapsus sanguineus, Helice tridens and Gryllus bimaculatus of the Arthropoda; Asterina pectinifera of the Echinodermata; and Halocynthia roretzi of the Protochordata. 4. These results demonstrate that an OXT-immunoreactive substance is widely present not only in vertebrates but also in invertebrates. 5. OXT seems to have been introduced into these invertebrates at an early stage of their phylogenetic history.     

Presence of pepsinogens immunoreactive to anti-embryonic chicken pepsinogen antiserum in fish stomachs: possible ancestor molecules of chymosin of higher vertebrates

1. Stomachs of adult teleosts and elasmobranchs reacted to an anti-embryonic chicken pepsinogen antiserum (anti-ECPg) as well as to an anti-adult chicken pepsinogen antiserum (anti-ACPg). 2. Zymograms and immunoblots of stomach extracts revealed that anti-ECPg- and anti-ACPg-reactive substances possess peptic activity. 3. The possible relationship between anti-ECPg-reactive pepsinogens in fish and prochymosins in higher vertebrates is discussed.     

Ultrastructural changes of the midgut epithelial cells in feeding and moulting nymphs of the tick Haemaphysalis longicornis

The midgut epithelial cells in nymphs fed on laboratory rabbits were examined during feeding and after detachment. The midgut epithelium at the unfed stage consisted of digestive cells of lower activity, containing such nutritive substances as protein, lipid and glycogen. As feeding proceeded, the cells became active in intracellular digestion. At the middle of the feeding stage, the spent digestive cells derived from the active digestive cells began to be replaced by the new digestive cells of lower activity. After detachment, the pinocytotic activity of the above cells increased greatly, and the digestive activity increased to some extent. As a result, many large endosomes were formed by fusion of numerous pinosomes. Thereafter, endosomes decreased in size as digestion proceeded and there was an increase of haematin granules. On day 7 after detachment, the new digestive cells of lower activity, belonging to the 'nutritional reserve' type, appeared adjacent to the spent digestive cells which had almost exhausted all endosomes, and these new cells had completely replaced the spent cells by day 3 after moulting.     

Repeated streptozotocin injections cause early onset of glomerulosclerosis in mice.

Diabetic nephropathy (DN), a major cause of end-stage chronic renal failure, is histologically characterized by glomerulosclerosis. To investigate the molecular mechanisms of DN, it is important to establish a stable model of glomerulosclerosis in mice, because genomic manipulation techniques (such as gene destruction or transgene insertion) are well established in rodent species. In this study, we found that repeated administrations of streptozotocin led to early onset of glomerular sclerotic lesions in C57BL/6 mice, accompanied with renal dysfunction. During the natural course of DN, glomerular endothelial cells decreased at 10 weeks after the start of streptozotocin-injections, whereas myofibroblastic mesangial cells became evident. Our results provide an animal tool to elucidate the molecular mechanisms of DN, for example to investigate vascular pathology in diabetic glomerular diseases.     

Decreased transport of D-glucose and L-alanine across brush-border membrane vesicles from small intestine of rats treated with mitomycin C

To elucidate the mechanisms underlying the dysfunctions of intestinal absorption induced by antitumor drugs, the effect of pretreatment with mitomycin C on sodium gradient-dependent D-glucose and L-alanine transports was studied in rat brush-border membrane vesicles. 24, 48, 96, or 120 h following a single intravenous injection of mitomycin C, brush-border membrane vesicles were prepared from rat small-intestines. The uptake of D-glucose and L-alanine was shown to be Na+ gradient-dependent even in the case of vesicles obtained from mitomycin C-treated rats, but uptake rates measured at 15 s and magnitude of overshooting effect in uptake of both solutes were decreased in vesicles maximally from 48 h mitomycin C-treated rats. The rate of D-glucose uptake calculated at 15 s recovered to the control level in vesicles prepared at 96 h and 120 h after mitomycin C-treatment, indicating that the effect of mitomycin C on Na+ gradient-dependent D-glucose transport would be fully reversible. Tracer exchange experiments under Na+ and D-glucose equilibrated conditions indicated that the Na+/D-glucose transporters were similarly operative in the vesicles from control and 48 h mitomycin C-treated rats. Rates of 22Na+ uptake measured at 15 s in vesicles from 48 h mitomycin C-treated rats, however, were increased. The increased permeability to Na+ might bring about a more rapid dissipation of the Na+ gradient in these vesicles and this would secondarily cause the decrease in Na+-dependent D-glucose uptake in vesicles from mitomycin C-treated rats.     

Random cloning of bent DNA segments from Escherichia coli chromosome and primary characterization of their structures.

A simple method for the selective detection of DNA segments containing a sequence-directed static bend was developed. Two-dimensional polyacrylamide gel electrophoresis performed at two different temperatures (60 degrees C and 10 degrees C) can effectively separate a bent DNA from a mixture of normal DNA. Using this method, a bank of plasmids carrying bent DNA inserts from the E. coli total chromosome was constructed. The primary characterization of a set of bent DNA segments randomly cloned from E. coli was presented.     

Action Spectra for Inhibition by Light of Accumulation of Bacteriochlorophyll and Carotenoid during Aerobic Growth of Photosynthetic Bacteria

Action spectra for the inhibition by light of the accumulationof photosynthetic pigments during the aerobic growth of a photosyntheticbacterium, Rhodobacter sphaeroides, and an aerobic photosyntheticbacterium, Erythrobacter sp. strain OCh 114, were determinedover the range of wavelengths from 380 to 870 nm. The actionspectra for the inhibition of accumulation of bacteriochlorophyllin both R. sphaeroides and Erythrobacter sp. strain OCh 114indicated that the maximum inhibition occurred at approximately400 nm and a low level of inhibition occurred at 575 and 770nm. In R. sphaeroides, the action spectrum for the inhibitionof accumulation of carotenoid paralleled that for the inhibitionof accumulation of bacteriochlorophyll over the same range ofwavelengths. These results indicate that in both species, grownunder aerobic conditions, the same photoreceptor is involvedin the inhibition. One possible candidate for the relevant photoreceptormay be the precursor(s) to bacteriochlorophyll. It is possiblethat the photoreceptor is decomposed by light absorbed by itselfor by an unidentified photoreceptor that absorbs blue light(a photo-sensitizer). It is suggested that the accumulationof carotenoid is dependent on the stability of the bacteriochlorophyll. (Received September 16, 1988; Accepted March 2, 1989)     

Low density lipoprotein and apoprotein B induce increases in inositol trisphosphate and cytosolic free Ca2+ via pertussis toxin-sensitive GTP-binding protein in vascular smooth muscle cells

Low density lipoprotein (LDL), a major cholesterol-carrying lipoprotein in the plasma, binds to its receptor through apoprotein B (Apo-B). The addition of LDL and Apo-B induced rapid (5 s), but transient increase in the inositol 1,4,5-trisphosphate (Ins-1,4,5-P3) level with K0.5 values of 1.1 and 0.07 microgram/ml, accompanied by increases of cytosolic free Ca2+ concentration [( Ca2+]i), in vascular smooth muscle cells (VSMC). The increases by LDL and Apo-B were both reduced by pretreatment of the VSMC with pertussis toxin. The early change in Ins-1,4,5-P3 involving a GTP-binding protein may function as an initial signal for the action of LDL in VSMC.