Ring formation of chromosomes nos. 19 and 20

Two patients with mosaicism for a ring F chromosome are described. Fluorescent stains identified the ring as No. 19 in one patient and No. 20 in the other. Since the majority of cells without the rings had 46 chromosomes, including four normal small metacentrics, the rings must have arisen after zygote formation. There appeared to be little, if any, influence on the phenotype.

Fluorescent staining of human chromosomes: identification of some common aberrations

With the development of fluorescent staining techniques and their application to human chromosomes, identification of the entire human karyotype is now possible. Of considerable value are the elimination of the guesswork in the pairing of the C group and sex chromosomes and the recognition and characterization of the translocation chromosomes in mongolism.

Utility of gaussian-type orbitals in molecular collisions: electronic excitation of the first positive system of the nitrogen molecule

The use of gaussian-type orbitals (GTO) as basis sets of electronic wave functions of molecules for calculating electron-collision excitation cross sections is discussed. A test calculation of the electron excitation cross section of the 2p state of atomic hydrogen at 60-1000 eV in which the hydrogenic wave functions were expressed as linear combinations of GTO indicates that an expansion of the is wave function by six GTO's and the 2p by four GTO's gives quite accurate results. Methods for evaluating the multicenter integrals which appear in the expressions of electron-excitation cross section (by the Born-type approximation) of diatomic molecules are described. Cross sections of direct electron excitation of the B(3)II(g) state (the first positive bands) of the N(2) molecule are calculated by this scheme, and the results are in good agreement with experiments.

A suggestion for the nomenclature of the fluorescent banding patterns in human metaphase chromosomes

With the application of fluorescent technique, it is now possible to recognize characteristic banding patterns in human chromosomes. A simple nomenclature for the bands is suggested according to their visual identification.

The establishment and chromosome analysis of a new cell line of Chinese hamster from spontaneous transformation in vitro

A male Chinese hamster cell line has been established through spontaneous transformation in a skin culture. Chromosome studies at passage 13 revealed one major and one minor type of pseudodiploid cells (77.3 and 20%). At passage 42, only the major subline persisted (78%). The two sublines, especially the major one, had selective advantage over other cell types in this cell line probably because they were more nearly genetically balanced. Autoradiographic studies indicated no overall increase in late replicating chromosomal elements in the two sublines. Both cell types lacked the X chromosome and chromosome 6, but they were largely compensated for by the presence of new marker chromosomes. However, more chromosomal material was missing in the minor type than in the major type, and this may account for the lower adaptability of the former.

Spontaneous meiotic chromosome abnormalities in male mice (Mus musculus)

Three types of spontaneous meiotic chromosome aberrations were described in mouse spermatocytes: (1) Precocious separation of XY chromosomes was observed in about 6% of cells in diakinesis and first metaphase; (2) chromosome degeneration appeared in 9.2 and 4.8% of cells at pachytene and at first metaphase, respectively; (3) polyploidy, in particular tetraploidy, occurred in 2.7 and 3.2% of cells at pachytene and first metaphase, respectively. These chromosome anomalies should be considered in cytological studies of the effect of noxious agents on chromosomes in mouse spermatocytes.

Spoilage bacteria in canned foods. II. Sulfide spoilage bacteria in canned mushrooms and a versatile medium for the enumeration of Clostridium nigrificans

Clostridium nigrificans was found to be a spoilage organism of canned mushrooms in Taiwan. A modified beef extract tryptone iron medium, both in broth and agar form, was designed for the detection and recovery of the organisms. A procedure of simple plate counting method of C. nigrificans was established.

Spoilage bacteria in canned foods. I. Flat sour spoilage bacteria in canned asparagus and the thermal death time

Bacillus stearothermophilus was found to be a cause of spoilage of asparagus canned in Taiwan. The F(250) and Z values of the isolates were 14.2 min and 17.8 F (-7.9 C), respectively.