Reconstitution of Embryo-Like Structures from Sea Urchin Embryo Cells: Distinction Between Cell-Cell and Cell-Substrate Associations

Sea urchin embryos can be dissociated into a suspension of single cells that reconstitute embryo-like structures. When reconstitution is conducted in stationary cultures the first step is attachment of the cells to the culture plate, which requires calcium and metabolic energy but not protein synthesis. We have found that protease treated cells form cell-cell associations in stationary cultures without attaching to the culture plates, and that cell-plate attachments are unaffected by inhibition of protein synthesis. These data suggest that cell surface proteins are needed for cell-plate attachment and that these proteins are present on freshly dissociated cells. We also demonstrated that butanol extracted cells attach to the plates, but do not form functional cell-cell associations unless the butanol extracted material is restored to them. We conclude that sea urchin embryo cells contain two classes of attachment components. The first class functions in the cell-plate attachments, is protease sensitive, and not extracted by butanol; the second class is necessary for cell-cell associations, is protease insensitive, and extracted by butanol. Since protease treated cells reconstitute embryo-like structures without attaching to the culture plates, only the second class of attachment components is necessary for embryo reconstitution.     

Pigments and a UV-absorbing substance in corals and a blue-green alga living in the Great Barrier Reef

Pigments and UV-absorbing substances in several species of coralsand a blue-green alga harvested in the environs of the GreatBarrier Reef were studied by measuring the in vivo reflectionspectra of intact samples and absorption spectra of their waterextracts with a recording spectrophotometer set on a biologicalresearch vessel. Red, pink, mauve and violet colors of fourspecies of Acropora were thus found to be due to differencesin the relative content of two pigments designated as P(pigment)-560and P-590, according to the maximum wavelength in mµ oftheir major absorption peaks. A yellow species of Acropora anda red species of Pocillopora contained different pigments, P-500and P-480, respectively. All these five species of corals contained,in addition to the above pigments, a UV-absorbing substancehaving an absorption peak near 320 mµ. The contents ofthis substance in the organisms seemed to be very high as judgedfrom its band height relative to band heights of the visiblepigment bands. Blue-green algal cells harvested near the sameenvirons contained a similar UV-absorbing substance in additionto phycobilin pigments. The spectral characteristics of thepigments and the UV-absorbing substance found in the coralsand alga are presented in this paper. ¹The present study was carried out in cooperation with Drs.F. T. HAXO, P. HALLDAL and S. W. JEFFREY on the research vessel,R. V. "Alpha Helix", of University of California during the1966 expedition to the Great Barrier Reef, North Queensland,Australia, and was supported by the National Science Foundationof the U. S. A. (Received December 3, 1968; )     

Paranucleospora theridion n. gen., n. sp. (Microsporidia,Enterocytozoonidae) with a Life Cycle in the Salmon Louse (Lepeophtheirus salmonis,Copepoda) and Atlantic Salmon (Salmo salar)

ABSTRACT. Paranucleospora theridion n. gen, n. sp., infecting both Atlantic salmon (Salmo salar) and its copepod parasite Lepeophtheirus salmonis is described. The microsporidian exhibits nuclei in diplokaryotic arrangement during all known life‐cycle stages in salmon, but only in the merogonal stages and early sporogonal stage in salmon lice. All developmental stages of P. theridion are in direct contact with the host cell cytoplasm or nucleoplasm. In salmon, two developmental cycles were observed, producing spores in the cytoplasm of phagocytes or epidermal cells (Cycle‐I) and in the nuclei of epidermal cells (Cycle‐II), respectively. Cycle‐I spores are small and thin walled with a short polar tube, and are believed to be autoinfective. The larger oval intranuclear Cycle‐II spores have a thick endospore and a longer polar tube, and are probably responsible for transmission from salmon to L. salmonis. Parasite development in the salmon louse occurs in several different cell types that may be extremely hypertrophied due to P. theridion proliferation. Diplokaryotic merogony precedes monokaryotic sporogony. The rounded spores produced are comparable to the intranuclear spores in the salmon in most aspects, and likely transmit the infection to salmon. Phylogenetic analysis of P. theridion partial rDNA sequences place the parasite in a position between Nucleospora salmonis and Enterocytozoon bieneusi. Based on characteristics of the morphology, unique development involving a vertebrate fish as well as a crustacean ectoparasite host, and the results of the phylogenetic analyses it is suggested that P. theridion should be given status as a new species in a new genus.     

黄山短尾猴的左右手倾向

就取食过程中惯用左手还是右手的问题,我们对安徽省黄山的一群短尾猴进行了研究。结果发现在调查的33只个体中,9只惯用右手取食,11只惯用左手取食,另外13只对左右手的使用没有偏好。而且短尾猴在左右手的偏好方面也没有性别或年龄的差异。以往的一些研究表明猕猴类动物习惯于用左手取食,但是研究群的短尾猴并没有表现出这种倾向。我们将短尾猴的研究结果与猕猴属其它种类进行了比较,并讨论了猕猴属在这一行为上的多样性。     

VINYL PHEOPORPHYRIN A5 IN THE INNER SEED COATS OF PUMPKINS

The pigments contained in the inner seed coats of Cucurbitapepo, C. maxima and C. moschata were investigated spectroscopicallyusing both intact tissues and their ether extracts. The pigment(s) contained in C. pepo and C. maxima was inferred to be "protochlorophyll"and/or Mg vinyl pheoporphyrin a₅ which are indistinguishablefrom each other by mere spectroscopic observations. The coatsof C. moschata were found to contain Mg-free vinyl pheoporphyrina₅ which has so far been reported to exist only in some Chlorellamutants. The spectra of these pigments in intact tissues wereremarkably different from those of the ether extracts, indicatingthe profound difference in their physical states in vitro andin vivo. It was discussed that the "protochlorophyll b" reportedearlier by SEYBOLD and EGLE might have been vinyl pheoporphyrina₁. (Received July 14, 1960; )