Cloning and expression of human nebulin cDNAs and assignment of the gene to chromosome 2q31-q32

We have isolated two nonoverlapping cDNAs encoding human nebulin, a muscle-specific protein. Northern hybridization analysis shows that nebulin is encoded by a huge message at least 25 kb in length. By hybridizing two nonoverlapping cDNAs to DNA isolated from rodent X human cell hybrids, we assign this presumably single-copy gene to human chromosome 2; sublocalization studies indicate that the nebulin gene is on the long arm of the chromosome, in the region 2q31-q32.     

Expression of transforming growth factor alpha and its messenger ribonucleic acid in human breast cancer: its regulation by estrogen and its possible functional significance

We have studied the estrogenic regulation and the potential autocrine role of transforming growth factor alpha (TGF alpha) in the human breast cancer cell line MCF-7. A biologically active apparent mol wt 30 k TGF alpha was identified by gel filtration chromatography in medium conditioned by MCF-7 breast cancer cells. We previously reported induction of TGF alpha levels in medium by 17 beta-estradiol. We now report correlated increases in TGF alpha mRNA, by Northern and slot blot analysis, after estrogen treatment of MCF-7 cells in vitro. In vivo experiments confirmed these data: estrogen withdrawal from MCF-7 tumor-bearing nude mice resulted in a decline in tumor size and TGF alpha mRNA levels. To explore the functional significance of TGF alpha in MCF-7 cells, anti-TGF alpha antibody was added to MCF-7 soft agar cloning assays. Inhibition of MCF-7 growth resulted, supporting an autocrine role for TGF alpha. Further experiments using an anti-EGF receptor antibody expanded this data, demonstrating inhibition of estrogen-stimulated monolayer MCF-7 cell growth. Examining the generality of TGF alpha expression, 4.8 kilobase TGF alpha mRNAs were seen in three other human breast cancer cell lines, MDA-MB-231, ZR 75B, and T47D. Expression of TGF alpha mRNA was detected in 70% of estrogen receptor positive and negative primary human breast tumors from 40 patients when examined by slot blot and Northern analysis. Thus, we have demonstrated broad expression of TGF alpha in human breast cancer, its hormonal regulation in an estrogen-responsive cell line, and its possible functional significance in MCF-7 cell growth.     

M?ssbauer spectroscopic studies of the cores of human, limpet and bacterial ferritins

Ferritin cores from human spleen, limpet (Patella vulgata) haemolymph and bacterial (Pseudomonas aeruginosa) cells have been investigated using 57Fe M?ssbauer spectroscopy. The M?ssbauer spectra were recorded over a range of temperatures from 1.3 to 78 K, all the spectra are quadrupole-split doublets with similar quadrupole splittings and isomer shifts, characteristic of iron(III), while at sufficiently low temperatures the spectra of all the samples show well-resolved magnetic splitting. At intermediate temperatures, the spectra from the human ferritin exhibit typical superparamagnetic behaviour, while those from the bacterial ferritin show behaviour corresponding to a transition from a magnetically ordered to a paramagnetic state. The spectra from the limpet ferritin show a complex combination of the two effects. The results are discussed in terms of the magnetic behaviour of small particles. The data are consistent with magnetic ordering temperatures of about 3 and 30 K for the bacterial and limpet ferritin cores, respectively, while the data indicate that the magnetic ordering temperature for the human ferritin cores must be above 50 K. These differences are interpreted as being related to different densities of iron in the cores and to variations in the composition of the cores. The human ferritin cores are observed to have a mean superparamagnetic blocking temperature of about 40 K, while that of the limpet ferritin cores is about 25 K. This difference is interpreted as being due not only to different mean numbers of iron atoms in the two types of core but also to the higher degree of crystallinity in the cores of the human ferritin.     

Porphyra nereocystis: A dual-daylength seaweed

Conchospores from the perennial conchocelis phase of the annual, epiphytic, marine red alga Porphyra nereocystis Anderson, which in nature lives on the large annual kelp Nereocystis luetkeana (Mertens) Postels et Ruprecht, are released in culture only in response to a short-day photoperiod treatment followed by a long-day treatment. Each treatment requires a minimum of three to four weeks and is enhanced by lower temperature during the second photoperiod treatment. To our knowledge P. nereocystis is the first known dualdaylength seaweed and requires a short-day-longday treatment for completion of its life cycle. This stringent environmental control of its reproduction appears to be an adaptation to coordinate conchospore production with the seasonal availability of its host kelp Nereocystis.Abbreviations LD long day - SD short day - SLD shortlong day     

Phosphopeptide analysis of phenylalanine hydroxylase isolated from liver cells exposed to hormonal stimuli.

Hormonal control of the phosphorylation of phenylalanine hydroxylase was studied by using rat liver cells incubated with [32P]Pi. After immunoprecipitation from cell extracts, the hydroxylase was subjected to proteinase digestion and subsequent sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. V8-proteinase digestion yielded one major 32P-labelled fragment, of approx. 9 kDa. Chymotrypsin digestion gave five 32P-labelled fragments ranging from approx. 39 kDa to approx. 10 kDa. Noradrenaline (10 microM) and glucagon (0.1 microM) enhanced the 32P content of all peptide fragments uniformly. Phorbol ester, in contrast with ionophore A23187, did not stimulate enzyme phosphorylation or enhance phenylalanine metabolism in liver cells. These results are discussed in relation to the nature of the protein kinase(s) that mediate phosphorylation of phenylalanine hydroxylase in liver cells.     

Interaction of genotype and parental environment in the adaptation of wild House mice Mus musculus to cold

Wild House mice, Mus musculus, were bred in two laboratory environments, one warm (controls) and one cold (Eskimo). At the seventh generation, mice of both stocks were cross-fostered at birth in both environments. In the warm environment, differences in both genotype and nest environment influenced growth: (1) Eskimo reared by Eskimo females were the heaviest of the four classes of fostered young; and (2) control foster parentage retarded growth. There was, however, no good evidence of differences in the reproductive performance of the four classes of fostered mice. In the cold environment, the effects of both genetical differences and of fostering were greater. Both the superior growth of Eskimo reared by Eskimo and the retarding effect of control foster parentage were more marked. Moreover, adult males with control foster parents had less fat than had those with Eskimo foster parents. Reproductive performance was also affected: (1) the young of the pairs with Eskimo genotype were heavier than the young of control pairs; (2) the litters of mice with Eskimo foster parents were larger than those of mice with control foster parents, and their young were heavier. Differences among the young of fostered mice represent a grandmother effect. Evidently, selection in a cold environment had led, not only to adaptive genetical changes in the ability to respond directly to cold, but also to changes in parental performance; and the latter enhanced the fitness, in the cold environment, of their offspring and grandoffspring.     

Biochemical Identification of the Two Races of Radopholus similis by Starch Gel Electrophoresis

Analysis of genetic variation between the banana and the citrus races of Radopholus similis by starch gel eleclrophoresis demonstrated that 7 of 16 enzyme-encoding loci could be used for their diagnostic separation. The two races are closely related arid share approximately 75% of the enzymes evaluated. The level of dissimilarities o1 inherited bands indicates that no gene flow occurs between the races. Aldolase, α + β esterase, glucose-6-phosphate dehydrogenase, isocitrate dehydrogenase, lactate dehydrogenase, malate dehydrogenase, and phosphoglucose isomerase are diagnostic markers of the races.     

CYTOLOGY OF HELMINTHOSPORIUM TURCICUM AND ITS ASCIGEROUS STAGE,TRICHOMETASPHAERIA TURCICA

Knox- Davies , P. S., and J. G. Dickson . (U. Wisconsin, Madison.) Cytology of Helmintho sporium turcicum and its ascigerous stage, Trichometasphaeria turcica . Amer. Jour. Bot. 47(5) : 328—339. Illus. 1960.–The cells of the vegetative hyphae were generally multinucleate. Interphase nuclei resembled those of higher organisms, with a matrix of thread-like chromatin material surrounding a spherical nucleolus. “Beaked” nuclei frequently associated with anastomosing hyphae were interpreted as migrating nuclei. Nuclear division in the vegetative hyphae was rapid. Various division stages were distinguished but it was difficult to make accurate chromosome counts. The nucleoli were discarded at prophase or prometaphase and were reorganized in daughter nuclei at telophase. An outstanding feature of nuclear division was that all the nuclei in a cell divided simultaneously. Conidiophores and conidia were occasionally joined by wide cytoplasmic connections. They were multinucleate throughout their development. Mechanisms therefore exist for the perpetuation of heterokaryons through the conidium. Ascus development was studied in a hybrid between a dark and an albino isolate. Crozier formation was typical and nuclear fusion occurred in the young ascus. Four nuclear divisions were completed in the ascus before there was evidence of ascospore delimitation. Further nuclear division took place in the ascospores whose cells were multinucleate. The occurrence of less than 8 ascospores in an ascus appeared to follow degeneration of nuclei rather than the incorporation of a number of division-Ill nuclei in a single ascopore. Chromosome counts and irregularities in the appearance and behavior of nuclei and chromosomes in the asci indicate that aneuploidy occurs in Trichometasphaeria turcica. It is suggested that aneuploidy is a common phenomenon in the conidial stage of the fungus H. turcicum, and possibly also in other imperfect fungi.