Linkages between seagrass,mangrove and saltmarsh as fish habitat in the Botany Bay estuary,New South Wales

Shallow-water vegetated estuarine habitats, notably seagrass, mangrove and saltmarsh, are known to be important habitats for many species of small or juvenile fish in temperate Australia. However, the movement of fish between these habitats is poorly understood, and yet critical to the management of the estuarine fisheries resource. We installed a series of buoyant pop nets in adjacent stands of seagrass, mangrove and saltmarsh in order to determine how relative abundance of fishes varied through lunar cycles. Nets were released in all habitats at the peak of the monthly spring tide for 12 months, and in the seagrass habitat at the peak of the neap tide also. The assemblage of fish in each habitat differed during the spring tides. The seagrass assemblage differed between spring and neap tide, with the neap tide assemblage showing greater abundances of fish, particularly those species which visited the adjacent habitats when inundated during spring tides. The result supports the hypothesis that fish move from the seagrass to the adjacent mangrove and saltmarsh during spring tides, taking advantage of high abundances of zooplankton, and use seagrass as a refuge during lower tides. The restoration and preservation of mangrove and saltmarsh utility as fish habitat may in some situations be linked to the proximity of available seagrass.     

Structural features of a sulphated,fucose-containing polysaccharide from the brown seaweed dictyota dichotoma

A sulphated heteropolysaccharide (～15% of the acid-extractable material) isolated from the brown alga Dictyota dichotoma contains residues of D-glucuronic acid, D-galactose, D-mannose, D-xylose, and L-fucose¹. Partial hydrolysis of the polysaccharide with acid gave one neutral and two acidic oligosaccharides. The behaviour towards periodate of the polysaccharide before and after partial hydrolysis, alkali-treatment, and methanolysis has been studied. Evidence is thereby provided that the polysaccharide is partially sulphated and composed of (1→4)-linked residues of D-glucuronic acid, D-galactose, D-mannose, and D-xylose, and (1→2)-linked L-fucose.     

Production of fertile transgenic wheat plants by laser micropuncture.

A modified, non-damaging, protocol for the production of fertile transgenic wheat (Triticum aestivum L. cultivar Giza 164) plants by laser micropuncture was developed. The new homemade setup secures the transformation of as many as 60 immature embryo-derived calli (10000 cells each) in less than one hour using a UV excimer laser with two dimensional translation stages, a suitable computer program and a proper optical system. Five-day-old calli were irradiated by a focused laser microbeam to puncture momentarily made self-healing holes ( approximately 0.5 microm) in the cell wall and membrane to allow uptake of the exogenous DNA. The plant expression vector pAB6 containing bar gene as a selectable marker for the herbicide bialaphos resistance and GUS (uidA) gene as a reporter gene was used for transformation. No selection pressure was conducted during the four-week callus induction period. Induced calli were transferred to a modified MS medium with 1 mg l(-1) bialaphos for regeneration, followed by selection on 2 mg l(-1) bialaphos for rooting. Three regenerated putative transgenic events were evaluated for the integration and stable expression of both genes and results indicated that this modified procedure of laser-mediated transformation can be successfully used in transforming wheat.     

Cellulolytic activities ofChaetomium globosum on different cellulosic substrates

The effect of cellulosic substrates on the production of extra-cellular cellulases and their cellulolytic activity inChaetomium globosum has been studied in shake flask cultures. Production of endoglucanase, exoglucanase and filter paper cellulase was highest with pure cellulose whereas -glucosidase was maximally induced by wheat straw. A suitable pretreatment for wheat straw was peracetic acid followed by NaOH and that of bagasse with NaOH for saccharification.

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Résumé On a étudié l'effet de substrats cellulosiques sur la production de cellulases extracellulaires et leur activité cellulolytique chezChaetomium globosum en culture en flacons agités. La production d'endoglucanase, d'exoglucanase et de cellulase type papier-filtre est maximum avec la cellulose pure tandis que la -glucosidase est induite de manière maximum par la paille de froment. La paille de froment est traitée de manière adéquate pour la saccharification par l'acide peracétique suivi de NaOH, la bagasse, par NaOH.

     

Cytogenetic effects in a group of traffic policemen in Cairo

The aim of this study was to evaluate the cytogenetic effects in humans exposed to automobile exhaust. The induction of chromosome damage was studied in an exposed group of 28 traffic policemen with exposure of over 10 years and a control group of 15 policemen trainers from the Faculty of Police. The percentage of chromosomal aberrations as well as the mean sister-chromatid exchanges were significantly higher among the traffic policemen than in the control group. The cause for this elevated chromosome damage is most likely due to their exposure to pollutants from automobile exhaust, however, the increase is not correlated with the blood lead level or the duration of employment. On the other hand, the increase in chromosome damage among the traffic policemen is enhanced further by smoking.     

Somatic embryogenesis and shoot regeneration from intact seedlings of Phaseolus acutifolius A., P. aureus (L.) Wilczek,P. coccineus L., and P. wrightii L.

A rapid, one-step procedure has been developed for inducing direct organogenesis and somatic embryogenesis in cultures of Phaseolus coccineus L., P. acutifolius A., P. aureus L. [Vigna radiata L. Wilczek] and P. wrightii L. Development of somatic embryos and shoot buds occurred within 6–8 weeks of culture from intact seedlings raised on MS (Murashige and Skoog 1962) medium supplemented with N⁶-benzylaminopurine (BAP). Shoot buds or embryoids originated from subepidermal tissue of the regions adjacent to the shoot apex, hypocotyl and cotyledonary axils. While P. acutifolius and P. aureus were regenerated via shoot formation and P. wrightii by somatic embryogenesis, both embryogenesis and shoot regeneration were observed in P. coccineus. Relatively higher levels of BAP, 50–80 M, were found to be optimal for inducing regeneration while lower concentrations were ineffective. About 40–70 shoots and 70–250 somatic embryos were produced per responding seedling. Regenerated shoots and somatic embryos developed into whole plants on a basal medium or the one supplemented with 1 M naphthaleneacetic acid.     

Effect of dermal tumours on temperature distribution in skin with variable blood flow

Several investigations have been made for the heat flow problems in skin and subdermal tissues under normal physiological and atmospheric conditions. This paper considers the existence of a malignant tumour in the underlying tissues of epidermis of a human body. The surrounding tissues are assumed to have normal physiological functions, namely self-controlled metabolic activity, variable blood flow and perspiration. For the malignant portion the metabolic activity is taken to be continuous and uncontrolled. The effect of this factor is studied on the temperature profiles of the skin.     

Platelet serotonin content and uptake in spontaneously hypertensive rats

Platelet serotonin (5-HT) content and uptake were studied in male SHR and WKY at various ages. Blood was withdrawn from the carotid artery under anesthesia and 5-HT levels determined from platelet rich plasma (PRP) using a HPLC technique coupled with an electrochemical detection method. Platelet 5-HT uptake was studied by incubating PRP at 37 degrees C for 10 sec with increasing concentrations of 3H-5HT. Lineweaver- Burk plots of 3H-5HT uptake were linear suggesting simple Michaelis- Menten uptake kinetics. The SHR had more platelets than age-matched controls and consequently a higher blood circulating pool of 5-HT. Nevertheless, the 5-HT platelet levels were similar to those of their age-matched rats. The 5 week-old SHR and WKY had greater numbers of platelets and higher 5-HT platelet levels than the older rats of both strains. The affinity constants (Km) and the maximal velocities (Vmax) of platelet 5-HT uptake did not differ significantly between the 12 week- and the 6 month-old SHR and WKY. These data suggest that the SHR do not show the same impairment in platelet 5-HT metabolism as observed in essential hypertension in man.     

Notes on Algerian aquatic fungi: Pythium pythioides

Pythium pythioides (Roze & Cornu) Ramsbottom is recorded from Algeria. Since its original discovery in 1869 this species had not been found back. A brief history is given and morphological and reproductive characters are discussed.     

Can the heart initiate some forms of hypertension?

An active role for the heart in the initiation of hypertension can be postulated in two different sets of conditions. 1) Activation of pressor reflexes from the ventricles, coronary arteries, or aorta has been shown to produce substantial rises of arterial pressure; experience with postcoronary bypass hypertension suggests that these reflexes could be responsible for some types of paroxysmal hypertension. 2) Increased cardiac action caused by either neural or humoral factors can initiate a rise in cardiac output and blood pressure; sustained hypertension could be produced experimentally in conscious dogs by electrical stimulation of the stellate ganglion or by continuous infusion of dobutamine in the left coronary artery. Evidence suggesting that this could occur in humans was derived from a study of the relationship of cardiac output to cardiopulmonary volume in essential hypertension.