Deoxyribonucleic acid hybridization among strains of lactobacilli

Hybridization of deoxyribonucleic acid (DNA) from Lactobacillus bulgaricus (ATCC 11842) with DNA of L. lactis (ATCC 12315), L. helveticus (ATCC 15009), and L. jugurt (ATCC 521) showed 86.0% reassociation with L. lactis, 4.8% with L. helveticus, and none with L. jugurt.     

NUCLEOLAR-DERIVED RIBONUCLEIC ACID IN CHROMOSOMES, NUCLEAR SAP, AND CYTOPLASM OF CHIRONOMUS TENTANS SALIVARY GLAND CELLS

The distribution of monodisperse high molecular weight RNA (38, 30, 28, 23, and 18S RNA) was studied in the salivary gland cells of Chironomus tentans. RNA labeled in vitro and in vivo with tritiated cytidine and uridine was isolated from microdissected nucleoli, chromosomes, nuclear sap, and cytoplasm and analyzed by electrophoresis on agarose-acrylamide composite gels. As shown earlier, the nucleoli contain labeled 38, 30, and 23S RNA. In the chromosomes, labeled 18S RNA was found in addition to the 30 and 23S RNA previously reported. The nuclear sap contains labeled 30 and 18S RNA, and the cytoplasm labeled 28 and 18S RNA. On the basis of the present and earlier analyses, it was concluded that the chromosomal monodisperse high molecular weight RNA fractions (a) show a genuine chromosomal localization and are not due to unspecific contamination, (b) are not artefacts caused by in vitro conditions, but are present also in vivo, and (c) are very likely related to nucleolar and cytoplasmic (pre)ribosomal RNA. The 30 and 23S RNA components are likely to be precursors to 28 and 18S ribosomal RNA. The order of appearance of the monodisperse high molecular weight RNA fractions in the nucleus is in turn and order: (a) nucleolus, (b) chromosomes, and (c) nuclear sap. Since both 23 and 18S RNA are present in the chromosomes, the conversion to 18S RNA may take place there. On the other hand, 30S RNA is only found in the nucleus while 28S RNA can only be detected in the cytoplasm, suggesting that this conversion takes place in connection with the exit of the molecule from the nucleus.     

Effect of N,P, and K on root yield and nutrient levels in the leaves and roots of rutabagas grown in a greenhouse

Summary Experiments were conducted to determine the influence of N, P, and K and of the NP and NK interactions on root yields and tissue concentrations of N, P, and K of rutabagas grown on a sandy loam soil under greenhouse conditions. Root yields were increased by applications of N and K but not by added P. The yield response to N was dependent on K supply. The highest dry matter content in roots was associated with the lowest rates of N and K and the lowest root yields. The N content of tissue at the early vegetative stage increased with increasing rates of N and decreased with increasing rates of P and K. The N content of root tissue at harvest increased at the highest rates of N but was unaffected by rates of P and K. The P and K content of root tissue increased with increasing rates of P and K, respectively. The levels of nutrients in early vegetative tissue associated with optimum yields were about 2.6, 0.24, and 2.0% for N, P, and K, respectively. The corresponding values in the leaf tissue at harvest were about 1.2, 0.12, and 1.5% N, P, and K, respectively. Contribution No.222.