Physiological studies on a coccoid marine blue-green alga (Cyanobacterium)

A coccoid marine cyanobacterium assignable to the genus Synechococcus has been isolated in axenic culture. This organism appears not to be a nitrogen fixer as it failed to reduce acetylene under either aerobic or anaerobic conditions. The specific growth rate was determined at six irradiance levels (5-, 15-, 30-, 50-, 100- and 150 μmol m^-2 s^-1) under continuous illumination and controlled temperature (20°C). The growth vs. incident irradiance curve and estimated light energy absorbed showed that growth saturates at a relatively low photon flux density and photosynthesis has a low compensation point. It attained its maximum division rate (1·4 divisions d^-1 = generation time, 18 h) at 30 μmol m^-2 s^-1. Such a low light-requiring planktonic cyanobacterium may be of importance in terms of both biomass and productivity towards the bottom of the photic zone.     

云南色球藻科新分类群

在对云南石林国家级风景区碳酸盐岩表面的气生蓝藻类进行研究时,发现色球藻科中的1个新 种和3个新变种。其中石林肾胞藻是中国特有属——肾胞藻属中至今发现的第2个种;3个变种均属于星球藻属。     

星球藻属一新种——中国星球藻

<正> 中国星球藻 新种 图版Ⅰ、图1—6;图版Ⅱ、图1—8。 Asterocapsa sinica Chu et S. G. Chen, sp. nov. Massa plantae grumosa, gelatinosa, olivaceo-viridis; cellululae sp(?)aericae veloblongae, aut per compressionem mutam angulatae; singulae, 2—4—8 vel plures in involucreo crasso, vaginato, Iamellato aut non lamellato, non confluente;vagina coloniae crassissima, rigida, lamellae confluentes in involucri margine habens, incolorata aut flava aut punicea, pleuromque adulta fuscescens; superficies vaginae cellularum singularum atque involucri coloniae protectionieus verruciformibus. brevis longisve minutis crassive, perfusa; cellulae 3—4 μ diam., coloniae 300—500 μ diam. cellulae intus homogeneae aut grosse granulatae(pseudovaeuoleae?), olivaceo-viridea, nitide caeruleo-virides aut fusco-virides,in 2—3 plana divisae.     

Algae from the Rhynie Chert

New material collected from the Rhynie Chert Bed (Siegenian age) has revealed new filamentous and unicellular algae. Two of the filamentous forms and one palmelloid form are described. Filamentous and unicellular algae are particularly common in a white kind of chert not previously reported and which is interpreted as having been formed by the in situ silicification of a silicate-rich pond.
Some rhizoid-nodes of Palaeonitella cranii (Kidston & Lang) Pia and a possible rhizoid-borne pro-embryo are also described and compared with similar structures in living Charophyta.     

In vitro and in vivo biosynthesis of xanthophylls by the cyanobacterium Aphanocapsa

Of the six carotenoids identified in the cyanobacterium Aphanocapsa, β-carotene, zeaxanthin, echinenone and myxoxanthophyll are the major pigments, whilst β-cryptoxanthin and 3-hydroxy-4-keto-β-carotene are present only in trace amounts. With the exception of zeaxanthin, the other xanthophylls could be formed in vitro from [¹⁴C]phytoene in high yields, especially β-cryptoxanthin and 3-hydroxy-4-keto-β-carotene. In a time course experiment of xanthopyll biosynthesis the flow of radioactivity from [¹⁴C]phytoene was followed through the pools of phytofluene, lycopene, and β-carotene. The reaction sequence from phytoene to xanthophylls is sensitive in vitro to both difunone, an inhibitor of carotene desaturation, and CPTA, an inhibitor of cyclization.