Isolation and Characterization of Δ6-Desaturase,an ELO-Like Enzyme and Δ5-Desaturase from the Liverwort Marchantia Polymorpha and Production of Arachidonic and Eicosapentaenoic Acids in the Methylotrophic Yeast Pichia Pastoris

The liverwort Marchantia polymorpha contains high proportions of arachidonic and eicosapentaenoic acids. In general, these C20 polyunsaturated fatty acids (PUFA) are synthesized from linoleic and alpha -linolenic acids, respectively, by a series of reactions catalyzed by Delta(6)-desaturase, an ELO-like enzyme involved in Delta(6) elongation and Delta(5)-desaturase. Here we report the isolation and characterization of the cDNAs, MpDES6, MpELO1 and MpDES5, coding for the respective enzymes from M. polymorpha. Co-expression of the MpDES6, MpELO1 and MpDES5 cDNAs resulted in the accumulation of arachidonic and eicosapentaenoic acids in the methylotrophic yeast Pichia pastoris. Interestingly, Delta(6) desaturation by the expression of the MpDES6 cDNA appears to occur both in glycerolipids and the acyl-CoA pool, although other lower-plant Delta(6)-desaturases are known to have a strong preference for glycerolipids.     

Factors influencing otolith strontium/calcium ratios in Anguilla japonica elvers

The effects of temperature and salinity on the concentration ratios of strontium (Sr) to calcium (Ca) within the sagittal otoliths of elvers of the Japanese eel, Anguilla japonica, were studied by spot analysis using a wavelength dispersive X-ray electron microprobe. A total of 340 elvers were used: 100 elvers were reared for 15 days under various salinity conditions (freshwater, one-third seawater, two-thirds seawater and pure seawater at 22 °C; 240 elvers were reared for 58 days under various water temperature conditions (12, 17, 22, 27 °C) in either freshwater or pure seawater. Otolith Sr/Ca ratios were found to be positively correlated with water salinity. On the other hand, the Sr/Ca ratios were not found to be significantly different among the various temperature groups. The above results strongly suggest that the physiological mechanism of incorporation of Sr and Ca within the otolith of an eurythermal fish, Japanese eel, does not change within this range of temperatures (12–27 °C).     

Determination of the freshwater mark in otoliths of Japanese eel elvers using microstructure and Sr/Ca ratios

The microstructure, in particular checks within the otolith edge, of Anguilla japonica glass-eels and elvers and changes in otolith Sr/Ca ratios were examined to ascertain the environmental history of the eels, especially with regard to the time when glass-eels entered the river, and as a benchmark for count daily increments. The percentage of glass eels and elvers with checks and the mean number of checks within the otoliths of glass-eels caught at four localities, Tosa Bay off Tosa City, the mouth of the Gokase River, the mouth of the Saigo River and the dam of the Tsuri River were 0% (0), 15.0% (0.2), 51.6% (1.0) and 100.0% (4.2), respectively. The Sr/Ca ratios and Sr content peaked in the region where checks were formed and the values decreased rapidly towards the edge of the checks; on the other hand, these decreased gradually in the otolith when checks were not formed. These checks were estimated to be formed by stress when the glass-eels were affected by ambient fresh water within the river. The innermost check was called the freshwater mark in the present study and this mark may be useful as a benchmark in studying the growth history of the eel before and after entering freshwater.     

Beneficial effect of pretreatment of islets with fibronectin on glucose tolerance after islet transplantation.

The scarcity of available islets is an obstacle for clinically successful islet transplantation. One solution might be to increase the efficacy of the limited islets. Isolated islets are exposed to a variety of cellular stressors, and disruption of the cell-matrix connections damages islets. We examined the effect of fibronectin, a major component of the extracellular matrix, on islet viability, mass and function, and also examined whether fibronectin-treated islets improved the results of islet transplantation. Islets cultured with fibronectin for 48 hours maintained higher cell viability (0.146 +/- 0.010 vs. 0.173 +/- 0.007 by MTT assay), and also had a greater insulin and DNA content (86.8 +/- 3.6 vs. 72.8 +/- 3.2 ng/islet and 35.2 +/- 1.4 vs. 30.0 +/- 1.5 ng/islet, respectively) than islets cultured without fibronectin (control). Absolute values of insulin secretion were higher in fibronectin-treated islets than in controls; however, the ratio of stimulated insulin secretion to basal secretion was not significantly different (206.9 +/- 23.3 vs. 191.7 +/- 20.2% when the insulin response to 16.7 mmol/l glucose was compared to that of 3.3 mmol/l glucose); the higher insulin secretion was thus mainly due to larger islet cell mass. The rats transplanted with fibronectin-treated islets had lower plasma glucose and higher plasma insulin levels within 2 weeks after transplantation, and had more favorable glucose tolerance 9 weeks after transplantation. These results indicate that cultivation with fibronectin might preserve islet cell viability, mass and insulin secretory function, which could improve glucose tolerance following islet transplantation.     

Polygynous Mating System of Trimma okinawae (Pisces: Gobiidae) at Kagoshima,Japan with a Note on Sex Change

Mating system, social structure and reproductive behaviour of the gobiid fish Trimma okinawae were studied at Akamizu, Kagoshima, Japan. Mating system of this species is polygyny. There were two types of habitat-related distribution patterns of male and female home ranges: females have home ranges outside a small territory of the male; female home ranges are covered by male territory. Spawnings take place with a cycle of four to five days during the spawning season of June to Sept. In the morning of the day of spawning, males stay at the spawning sites. Females visit the site and spawn with the male. On days between spawnings males exhibit courtship displays at female home ranges. Higher reproductive success is not connected with frequency of such courting of the male, but with male size. The largest female of a social unit changes into a male when the dominant male is removed, which shows that T. okinawae is a hermaphrodite.     

Reproductive behavior of the territorial herbivoreStegastes nigricans (Pisces: Pomacentridae) in relation to colony formation

Reproductive behavior of the herbivorous damselfishStegastes nigricans was studied. Both males and females held individual feeding territories, which were distributed contiguously and formed colonies. Spawning season was from June to September. Females visited males' territories and spawned eggs on the algal nest. Males tended eggs until hatching but exhibited less care taking behavior than other damselfishes. The mating system was promiscuous in that both males and females spawn with several mates, even within a single day. However, only 1 female was accepted in the nest at a time. The restriction of the number of mates in the nest may be an adptation to prevent the sneaking which was often conducted by other males of the same colony, and may also be avoidance of disturbing the spawning female. Most spawnings were done among members of the same colony and inter-colonial spawnings were rare (27 cases of 333 spawnings observed). The results of this study suggest that colonial distribution ofS. nigricans may bring several benefits in reproduction to the colony members (e.g. easy mate findings within fellow colony members), but also seems to bring costs (e.g. restriction of number of mates).     

Increased renal vascular reactivity to norepinephrine in stroke-prone spontaneously hypertensive rat (SHR)

Vascular responses of isolated perfused kidneys to norepinephrine, angiotensin II and KCl were examined in stroke-prone spontaneously hypertensive rats (SHR-SP), stroke-resistant SHR (SHR-SR) and control Wistar Kyoto rats (WKR) at 8 to 10 weeks of age. Average values of systolic blood pressure were 181, 155 and 122 mmHg in the SHR-SP, SHR-SR and WKR, respectively. Basal renal vascular resistance was identical among these rats. In response to norepinephrine, the SHR-SP demonstrated shift in the dose-response curve to the left and lower vasoconstrictor threshold than the controls. The SHR-SR was intermediate between the SHR-SP and the controls in the response to norepinephrine. For angiostein II, the SHR-SP but not SHR-SR displayed a slightly greater response than the controls. However, response to KCl was not significantly different among these three strains of rats. The results suggest that the SHR-SP rats have an intrinsic augmentation of renal vascular reactivity to norepinephrine, which in turn leads to rapid elevation of blood pressure at the early hypertensive stage.     

Secretory granules of B-cells in the synovial membrane

Summary Ultrastructural and cytochemical studies have been made on secretory granules of B-cells (fibroblast-like cells) in the knee-joint synovium. The secretory granules were membrane-bounded spherical or slightly elongated bodies, 150 to 350 nm (average 230 nm) in diameter and had a homogenous matrix with several cores. These granules were found in B-cells of all animal species examined; they were numerous in mice and rats, and few in guinea pigs, rabbits and man. Ultrastructural and cytochemical examinations revealed that the Golgi apparatus was involved in the formation of the secretory granules. Unlike lysosomes, they showed no acid phosphatase activity. The granule matrix was positively stained by Thiéiy's periodic acid-thiocarbohydrazidesilver proteinate technique, and the cores were digested by protease. These findings suggest that the granule matrix contains mucopolysaccharide(s) and/or glycoprotein(s) and the core material is largely proteinaceous in nature.     

Plasma norepinephrine and dopamine-β-hydroxylase in genetic hypertensive rats

The relationship between blood pressure, plasma norepinephrine (NE), dopamine-β-hydroxylase (DBH) activity and age was investigated in spontaneously hypertensive rat (SHR), a stroke-prone substrain of the SHR and control Wistar-Kyoto rat (WKR). Blood pressure of both SHR strains increased with age and was significantly higher than that of the WKR at all ages tested (3 15 weeks). The blood pressure of stroke-prone SHR was significantly higher than that of the regular SHR after 6 weeks of age. Plasma DBH activity decreased with age in each strain, although the SHR, and especially the stroke-prone SHR, had significantly higher DBH than the controls at an early age. Plasma NE in the WKR did not change with age. Increased plasma NE was observed only in the young SHRs. The highest values were found in the 6 week old stroke-prone SHR. These data suggest that plasma DBH activity is not correlated directly with plasma NE or blood pressure, but that increased sympathetic nerve activity may occur during the development of hypertension in the SHR and the stroke-prone SHR.     

Promotion of plantlet formation from somatic embryos of carrot treated with a high molecular weight extract from a marine cyanobacterium

Summary Somatic embryos of Daucus carota L. developed into plantlets at high frequency after addition of an extract from a marine cyanobacterium, Synechococcus sp. NKBG 042902. High molecular weight, nondialyzing fraction, separated from the extract, possessed enhanced plantlet formation promoting activity. Plantlet formation frequency was 60 % after addition of nondialysate (100 mg/l) compared to 28 % without addition. Embryos treated with the nondialysate contained five times more chlorophyll than nontreated embryos after 6 days of culture. The chlorophyll a/b ratio of 4-day old treated somatic embryos was found to be similar to that of zygotic embryos. However, the chlorophyll a/b ratio of plantlets induced from nontreated somatic embryos was variable. Nondialysate was fractionated by ultracentrifugation and an active component obtained, which gave a maximum plantlet formation frequency of 71 %, and induced rapid greening of shoots.Abbreviations MS Murashige and Skoog medium - 2,4D 2,4-dichlorophenoxyacetic acid - PCV packed cell volume - E Einstein - Chl Chlorophyll - vvm volume of air, volume of medium per minute