Impatiens parviflora DC. — a natural host of cabbage black ringspot and cucumber mosaic viruses

Identification trials were carried out to determine a virus-like disease ofImpatiene parviflora DC. Two forms of foliar symptoms were observed:

1. a)
   Chiorotie and necrotic areas sometimes fallen out, leaving the leaves “shot holed”;     

HISTOLOGICAL CHANGES DURING THE DEVELOPMENT OF THE BOVINE NUCHAL LIGAMENT

The histological changes occurring during the development of the bovine nuchal ligament have been observed in sections of formalin-fixed material from 21 animals ranging in age from 110 days of gestation to 10 yr. The elastic fibers which constitute the bulk of the adult ligament were initially few in number. During fetal development, the fibers showed a rapid increase both in number and in their stainability with the usual elastic stains. The average diameter of these elastic fibers increased only slowly until the last uterine month, at which time it began to increase very rapidly. This rapid rate of increase continued through the first 6 postnatal months, after which the rate of increase slowed markedly. However, the fiber diameter continued to rise steadily throughout the period of the study. During the fetal stage of development, the fibroblastic cells of the ligament exhibited unusual nuclear appearances which distinguish them from other fibroblasts. These consisted of marked clumping of the chromatin and an associated nuclear vacuolation or vesiculation. While these changes seem likely to be artefacts of fixation, their temporal correlation with elastin deposition and their demonstration in other tissue cells engaged in elastin production suggest that the factors responsible for these appearances may be related to elastin synthesis.     

Growth of Mycobacterium lepraemurium in Cultures of Mouse Peritoneal Macrophages

Successful growth of Mycobacterium lepraemurium was observed in cultures of mouse peritoneal macrophages. The optimal host cell maintenance medium was composed of 40% horse serum, 50% of the chemically defined medium NCTC 109, and 10% of a 1:5 dilution of beef embryo extract, supplemented with both liver extract and ferric nitrate. Multiplication of the bacilli was observed in 1 week and maximal growth in 6 to 7 weeks. All macrophages were filled with tens to hundreds of the organisms in cultures showing maximal growth. Glycerol caused an increase in the normal length of M. lepraemurium, without a corresponding increase in the number of the bacilli. Elongation of M. lepraemurium was observed 3 or 4 days after infection. Rapid and uniform growth of M. lepraemurium was achieved in serially transferred cultures (subcultures). The cumulative increase of the number of intracellular bacilli was 1.4 x 10(20)-fold in 14 transfers over a period of 68 weeks in one series, and 10(17)-fold in 12 transfers over a period of 56 weeks in another series. The generation time of M. lepraemurium was 7 days, a growth rate which approximates the fastest growth of the organisms in vivo. Organisms harvested from cultures at various stages of growth produced murine leprosy in mice, but showed no growth in bacteriological media. The present model offers an opportunity for studies on the host-parasite relationship without the complication of extracellular growth of the parasites.     

Factors determining the biosynthesis of griseofulvin and similar substances

Была высказана гипотеза, что биосинтез гризеофульвине, цитромицетина, фульвиновой кислоты, фусаeубине, руброфусарина и родствеооых им вешеств протекаеР не путем конденсации линейнон цепочки, а из двух более коротких цепочек, которые возникают конденсацией 4 и 3 ацетатных единп. реакции, осушествляющиеся на уровне этих цапочек (илн прнмежувочных структур) метиляция, редукция, и, возможно, последующая дегидратация или только эноэизация— определяют направление дальнeйшeй кондeнсации в такой стeпeни, что конeчныe продуктыотдичаются своeй структурой.     

BIOSYSTEMATIC STUDIES IN THE BOUTELOUA CURTIPENDULA COMPLEX. I. THE ANEUPLOID RHIZOMATOUS B. CURTIPENDULA OF TEXAS

Gould , F. W., and Z. J. Kapadia . (A. & M. College of Texas, College Station.) Biosystematic studies in the Bouteloua curtipendula complex. I. The aneuploid rhizomatous B. curtipendula of Texas. Amer. Jour. Bot. 49(8): 887–891. Illus. 1962.—Widespread throughout central U.S. is a rhizomatous form of B. curtipendula that basically is tetraploid (2n = 40). In the southwest the predominant type is a caespitose aneuploid with a high chromosome number (2n = ca. 80 to 2n = ca. 102). The present study has shown the presence of an extensive series of rhizomatous aneuploids in central Texas, with chromosome numbers ranging from 2n = 41 to 2n = 64. The distribution of these plants is centered about the region of overlap in the ranges of the 2 previously mentioned types. Available evidence indicates that the rhizomatous aneuploids have arisen through hybridization of the caespitose aneuploids and the rhizomatous tetraploids.     

Biosynthesis of methionine in an ethionine-resistant strain ofCandida utilis

The strainCandida utilis T 20 adapted to a high concentration of ethionine, excretes considerable amounts of methionine in a synthetic medium, about 40 times as much as the original non-adapted strain. At the same time, the amount of methionine in yeast cells incrncreased, predominantly in the pool (9 times as much as in the control). This ability to produce greater amounts of methionine in the pool or to excrete it into the medium is not permanent, since after 5 passages on agar with ut ethionine the amount of methionine was practically not increased as compared with the original non-adapted strain. An increase in free methionine and of methionine excreted into the medium was found on cultivating the strain in a molasses-containing medium, too.