Purification of Growth-Promoting Peptides and Proteins,and of Histones,by High Pressure Silica gel Chromatography

A rapid method for the purification of histones and a variety of growth-promoting proteins and peptides by chromatography on silica gel has been developed. The isolation of the growth-promoting components of serum has been hampered by excessive losses associated with the use of water-based purification methods. The solubility of many growth-promoting serum proteins in acidic methanol-H₂O solutions (eg. insulin, albumin, the somatomedins) provides a basis for purification on high-pressure silica gel columns, while peptides and histones can be purified in similar solvents. After column chromatography, the solvent is removed by flash-evaporation, or the protein may be precipitated directly from the solvent by neutralization of the pH and the addition of ethanol. The retention of biological activity (eg. somatomedin-C binding to insulin receptors and cell-growth stimulation) and recovery are excellent.     

Artificial insemination of the American lobster (Homarus)

A technique has been developed for artificially inseminating freshly molted female lobsters (Homarus). Using the criterion that eggs were fertilized if they showed development of normal cleavage patterns, at least 49.5% of the inseminated females extruded fertilized eggs. Sixty-two percent of the fertilized eggs developed to the eyespot stage, and 26.6% of these subsequently hatched. Eggs were not fertilized in 7.7% of the extrusions. In 42% of the samples, it was not possible to establish whether fertilization had occurred because either samples were collected prior to initiation of cleavage or eggs were too poorly preserved to assess cleavage with confidence. It is probable that many of the eggs that were evaluated as equivocal were also fertilized. This technique should be valuable in the experimental and commercial aquaculture of lobsters and might be directly applicable to other crustaceans.     

Direction of Travel of RecBc Recombinase through Bacteriophage Lambda DNA

We examined linkage relationships for RecBC-mediated recombination in lytic cycle crosses of lambda phages bearing two cohesive end sites (cos) oriented in the same direction. The relationships obtained imply that a given recombinant tends to be packaged from the cos site that is the nearer one to the right of the exchange. In view of the previously established coupling of entry of a recombinase at a cos cut and initiation of DNA packaging by that cos cut, these results imply that the recombinase (presumably the RecBC gene product) enters lambda's chromosome at the right end.     

The powdery mildew disease of rubber (Oidium heveae) is jointly controlled by the winter temperature and host phenology

International Journal of Biometeorology - Rubber powdery mildew disease (Oidium heveae) is a serious threat to natural rubber production (Hevea brasiliensis) in some rubber developing regions of...     

An engineering analysis of rotating sieves for hybridoma cell retention ins stirred tank bioreactors

The use of internal rotating sieves for perfused hybridoma culture offers unique advantages but has been up to now largely empirical. Calculations have been performed on a 15 l spinfilter stirred tank in order to have an idea of hydrodynamic conditions inside and outside the rotating sieve. The large peripheral velocity value, resulting from sieve rotation (compared to axial and radial velocities) is expected to affect strongly sieve surface colonization by cells; this is confirmed by lab scale experiments, showing that cell colonization is prevented providing sieve rotation exceeds a defined value (around 0.6 m.s.1 tip speed); the fluid removal force calculated under these conditions appears to be in the range of 10 pN, similar to the adhesion force already reported for mammalian cells attached to inorganic substrata.     

The effect of manganese deficiency on lipid content and composition in Brevibacterium ammoniagenes

Summary Cells of Brevibacterium ammoniagenes grown under manganese deficient conditions contain less total lipids at the end of the logarithmic growth phase and the phospholipid content of these cells is lower over the whole fermentation period in comparison to those growing where the supply of manganese is sufficient.Phosphatidyl glycerol, cardiolipin, phosphatidyl inositol and phosphatidyl inositol mannoside were identified. There were quantitative, but no qualitative differences in the phospholipid composition. The phosphatidyl inositol mannoside content was greatly lowered under manganese deficiency, whereas the phosphatidyl glycerol and cardiolipin content were greatly increased.     

Eiweißspindeln von Valerianella

Zusammenfassung Bei allen daraufhin untersuchten Pflanzen vonValerianella Locusta, die aus verschiedenen Gärtnereien stammten, wurden durch mehrere Jahre hindurch zu jeder Jahreszeit in der unteren Blattepidermis Eiweißspindeln festgestellt. In anderen Geweben treten diese Gebilde nicht auf. Das Vorkommen dieser Zellinhaltskörper ist nicht auf eine Spezies allein beschränkt, sondern wurde bei verschiedenen Arten der GattungValerianella beobachtet. Dies, sowie das Fehlen von protoplasmatischen x-bodies spricht dafür, daß es sich bei den Eiweißspindeln vonValerianella nicht wie bei denen von Cactaceen, Solanaceen und anderen Pflanzen um zytologische Symptome einer Viruskrankheit handelt; es dürften diese Inhaltskörper vielmehr ein zytoplasmatisches Gattungsmerkmal vonValerianella darstellen.     

Stomata-Zahl der Hochblätter von„Poinsettia“

Zusammenfassung Die roten Hochblätter vonEuphorbia pulcherrima besitzen unterseits weniger Stomata als die grünen Laubblätter.