AN IN SITU STUDY OF RECRUITMENT,GROWTH AND SURVIVAL OF SUBTIDAL MARINE ALGAE: TECHNIQUES AND PRELIMINARY RESULTS12

Fouling plates (Plexiglas squares and concrete blocks) were bolted in a horizontal position to racks on the ocean floor at a depth of 12 m. Some of these were periodically taken from the sea, subjected to nondestructive microscopic survey in the laboratory, and then replaced. Others were: a) left undisturbed as controls; b) variously caged to exclude larger predatory animals; or, c) had sediment removed from them at intervals. Populations developing on the periodically surveyed plates were similar to those on undisturbed plates. Populations on undisturbed plates were significantly different from those on partially caged plates. The exclusion of large predators by complete caging resulted in highly significantly different communities from those on partially caged plates. Completely caged Communities were composed mainly of worms, barnacles and bryozoans. Summer-installed plates supported significantly different populations at the end of the experimental period (12 mo) from winter-installed plates. Plant growth rates were slow, not exceeding 2 cm/mo, and the mortality rates were often high. A few species had high rates of recruitment and survival each month. Most had high recruitment only in the most favorable growth periods and high loss rates. Physical conditions on the sea floor were measured. The methods developed during this study make it possible to quantitatively describe the growth and reproduction of populations of benthic marine algae in the sea.     

Carbohydrates of the seaweeds,Desmarestia ligulata and D. firma

Crystalline mannitol and some oligosaccharides were separated from ethanolic extracts of Desmarestia ligulata and D. firma. Laminaran, ‘fucans’ and alginic acid were also isolated from both species. The laminaran from D. ligulata comprised both M- and G-chains but no M-chains were found in the laminaran from D. firma. In both species the amount of ‘fucan’ was small, particularly in D. firma. Both ‘fucans’ contained glucuronic acid, galactose, xylose and fucose and that from D. ligulata also contained mannose. After sequential extraction of D. ligulata with water, acid and alkali evidence was obtained for the presence of cellulose, a uronan, and protein in the residual material.     

ENDOGENOUS CYTOKININS,AUXINS, AND ABSCISIC ACID IN RED ALGAE FROM BRAZIL1

Endogenous cytokinins, auxins, and abscisic acid (ABA) were identified and quantified in 11 red algae collected from the Brazilian coast. Field materials and two isolates cultured in the laboratory were extracted with various solvents and buffers containing a mixture of appropriate internal standards, purified by solid‐phase extraction followed by immunoaffinity chromatography, and analyzed by liquid chromatography–tandem mass spectrometry. Isoprenoid cytokinins (free and conjugated forms of isopentenyladenine [iP], cis‐zeatin [cZ], and trans‐zeatin [tZ]) were detected in all species with concentrations of cZ and iP forms being higher than tZ forms. Dihydrozeatin (DHZ) and its metabolites were only detected at very low levels in nine of the studied species. Aromatic cytokinins (6‐benzylaminopurine [BA], ortho‐ and meta‐topolin [oT and mT]) were not detected in any of the samples. The cytokinin profile of Chondracanthus teedei (Mert. ex Roth) Kütz. was distinct in comparison to other species with para‐topolin (pT) derivatives detected in low concentrations. The main auxins present in all species were free indole‐3‐acetic acid (IAA) and indole‐3‐acetamide (IAM). Indole‐3‐ethanol (IEt), indole‐3‐acetyl glutamic acid (IAGlu), and indole‐3‐acetyl leucine (IALeu) were detected in a few species at low concentrations. ABA was present in all species analyzed except for Hypnea nigrescens Grev. ex J. Agardh. No ABA conjugates were detected in any species. These results confirm that cytokinins, auxins, and ABA were common constituents in red seaweeds, with this being the first report of the occurrence of ABA in Rhodophyta. The complexity of the hormone profiles suggests that plant hormones play a role in regulating physiological processes in Rhodophyta.     

纤维素分解菌对不同纤维素类物质的分解作用

经过CMC平板、滤纸液化和摇瓶培养试验 ,发现 6株菌中 ,产黄纤维单胞菌 (CellulomonasFlav igena)和康氏木霉 (Trichodermakonigii)分解纤维素类物质的能力比较强 ,对来源不同的纤维素类物质分解能力差异很大 ;真菌与细菌一起接种时 ,分解纤维素类物质的速度明显高于其中任何一个单一菌株 ,说明纤维素类物质的分解需要多种微生物的联合作用