Ovomucoid intervening sequences specify functional domains and generate protein polymorphism

Two thirds of the natural chicken ovomucoid gene has been sequenced, including all exons and the intron sequences surrounding all fourteen intron/ exon junctions. The junction sequences surrounding four of the introns are redundant; however, the sequences surrounding the other three introns contain no redundancies and thus the splicing sites at either end of these three introns are unambiguous. The splicing in all cases conforms to the GT-AG rule. The ovomucoid gene sequence around intron F can be used to predict the cause of an internal deletion polymorphism in the ovomucoid protein, which is an apparent error in the processing of the ovomucoid pre-mRNA. We also compare the structural organization of the ovomucoid gene with the ovomucoid protein sequence to examine theories of the evolution of ovomucoids as well as the origin of intervening sequences. This analysis suggests that the present ovomucoid gene evolved from a primordial ovomucoid gene by two separate intragenic duplications. Furthermore, sequence analyses suggest that introns were present in the primordial ovomucoid gene before birds and mammals diverged, about 300 million years ago. Finally, the positions of the introns within the ovomucoid gene support the theory that introns separate gene segments that code for functional domains of proteins and provide insight on the manner by which eucaryotic genes were constructed during the process of evolution.     

Ultrastructural comparison of smooth muscle from ovarian follicle and oviduct of the golden hamster

Summary Ultrastructural characteristics of smooth muscle taken from ovarian follicles and oviducts of hamsters are compared. Differences between the two muscle types are more quantitative than qualitative, thus confirming that follicular muscle is a true smooth muscle with no unique characteristics. While both muscle types contain 50–80 Å filaments, -glycogen deposits, and organelles characteristically found in smooth muscle, the oviductal cells have substantially more sacs, tubular structures, sarcoplasmic reticulum, and mitochondria. Another difference concerns the cellular junctions; the oviductal cells exhibit nexuses, whereas the follicular cells show desmosomelike junctions. Based on ultrastructural differences, follicular smooth muscle seems to be a relatively toneless muscle suited for short, infrequent contractions, whereas oviductal smooth muscle is probably involved in more active tonic contractions.Supported by an Institutional Research Grant from Texas Women's University, by NIH Grant HD 12988, and by the Department of Anatomy at Wright State University     

Steroid sulphatase levels in XX males,including observations on two affected cousins

Summary Quantitative assays of steroid sulphatase in XX males have shown that some individuals have two functional loci, and others only one. Two affected cousins, who cannot share the same X-chromosome, nevertheless have male levels of steroid sulphatase, suggesting functional abnormality of the X chromosome.The hypothesis is advanced that these and other unusual features of X-chromosome function in some XX males, could be explained if such cases were due to an autosomal mutation, exercising its effect by causing abnormal inactivation of a subterminal area of Xp which normally escapes the inactivation process.     

Heparin-inhibitable lectins: Marked similarities in chicken and rat

Extracts of young rat lung contain a heparin-inhibitable lectin that closely resembles one recently purified from chicken liver. Both lectins interact with heparin and N-acetyl-D-galactosamine, and were purified by gel filtration on Sepharose CL-2B followed by affinity chromatography on heparin-Sepharose. They both behave as high molecular weight aggregates that can be dissociated into two peptides with apparent molecular weights of 13,000 and 16,000 by gel electrophoresis in SDS. Samples of purified lectin contained up to 20% DNA by weight, and the degree of lectin aggregation and hemagglutination activity was greatly reduced by treatment with micrococcal nuclease without inhibiting heparin-binding activity. Association of lectin with DNA is an artifact of homogenization in high salt, since only 2% of the lectin is found associated with a purified nuclear fraction.     

Resting eggs, seasonal dynamics, and production of Bosmina longispina maritima (P. E. Muller) (Cladocera) in the northern Baltic proper

The seasonal dynamics and production of Bosmina longispina maritimawas studied both in the pelagic zone and bottom sediments ofthe northern Baltic proper in 1979. Resting eggs started tohatch in April–May, but the pelagic zone population didnot show signs of increase until August; this is typical forthe species in this area. Relatively few of those hatched inthe spring and early summer survived the low temperatures andlack of food below the thermocline. The population increasewas started with individuals hatched after the thermal stratificationweakened. From August until October the number of resting eggsin the sediment rose in direct response to their productionin the pelagic zone. A new hatching period began in October–November,but conditions in the pelagic zone were not suitable for theirfurther development. Such mistiming of hatching may, along withother factors, help to explain the large annual variations inthe productivity of B. longispina maritima in the Baltic. Sexualreproduction was found to be of relatively greater importancein the study area than in the areas where Bosmina reaches higherproductivity. This was assumed to be due to more intense selectionpressures in the prevailing conditions.     

Murine p53 inhibits the function but not the formation of SV40 T antigen hexamers and stimulates T antigen RNA helicase activity

We have characterized the effects of p53 on several biochemical activities of simian virus 40 (SV40) large tumor (T) antigen. While p53 induced a strong inhibition of the T antigen DNA helicase activity, surprisingly, its RNA helicase activity was stimulated. This supports the liklihood that the DNA and RNA helicase activities of T antigen reflect discrete functions. p53 did not significantly affect the ATP-dependent conversion of T antigen monomers to hexamers. However, the ability of these hexamers to assemble on a DNA fragment containing the viral origin was impaired by p53. Thus, these results suggest that p53 inhibits the function but not the formation of T antigen multimers. This conclusion was further supported by the observation that the addition of a purified p53:T antigen complex was as inhihitory as free p53 to the DNA helicase activity of free T antigen. Thus our data indicates that the targets of p53 inhibition are the functional units of T antigen, namely the hexamers.     

A new variant glyoxalase I allele that is readily detectable in stimulated lymphocytes and lymphoblastoid cell lines but not in circulating lymphocytes or erythrocytes

We describe an allele of the human glyoxalase GLO locus that encodes an enzymatically inactive form of the protein, which would not have been detected if only circulating erythrocytes and lymphocytes had been studied. The new allele is named GLO*3 and its protein product, GLO 3. Circulating blood cells of GLO*2/GLO*3 heterozygotes have just one electrophoretic band that migrates as the normal 2-2 dimer. Lymphoblastoid cell lines and phytohemagglutinin-stimulated lymphocytes from the same individuals have two electrophoretic bands, one with the mobility of the 2-2 dimer and one with the mobility of the 2-1 dimer that is present in GLO*2/GLO*1 heterozygotes, but a band with the mobility of the 1-1 dimer is not present. Therefore, the GLO*3 allele encodes a monomer that has the electrophoretic mobility of GLO 1 but is enzymatically inactive unless it is combined with normal monomers in 2-3 and 1-3 heterodimers. The failure to detect the GLO 3 protein in red cells and unstimulated lymphocytes is attributed to a relatively great instability or small rate of production in those cells. Consistent with this interpretation is the reduction of GLO activity in red cells of GLO*2/GLO*3 and GLO*1/GLO*3 heterozygotes to 65% or less of that in normal homozygotes and heterozygotes, while the activity of GLO*3 heterozygous lymphoblastoid cells is about 80% of normal. In contrast, the GLO activity of lymphoblastoid cells that had one copy of the GLO locus deleted by γ-irradiation was 50%–60% of normal. Our observations indicate that certain kinds of mutant alleles of the GLO locus, and perhaps other loci, may not be detected in electrophoretic surveys on circulating blood cells only. The segregation of alleles that are not expressed in circulating red and white blood cells could confuse attempts to determine parentage, as they might have in the family described here. The observations also demonstrate the feasibility of mapping human genes by using ionizing radiation to create partial chromosome deletions in cultured cells.     

Evidence for Glucocorticoid Target Cells in the Rat Optic Nerve. Hormone Binding and Glycerolphosphate Dehydrogenase Induction

Abstract: Biochemical evidence suggests that neuroglia are responsive to glucocorticoids, yet previous studies of glucocorticoid localization have typically failed to demonstrate significant uptake by neuroglial cells. To further investigate this problem, we measured glycerol-3-phosphate dehydrogenase (GPDH) activity and glucocorticoid receptor binding capacity in normal rat optic nerves and in those undergoing Wallerian (axonal) degeneration. Binding studies were also performed on hippocampus and anterior pituitary for comparison purposes. Normal optic nerve preparations possessed a high level of GPDH activity that was glucocorticoid-inducible and that increased further following axonal degeneration. Antibody inactivation experiments demonstrated the presence of more enzyme molecules in the degenerating nerve preparations. Correlative immunocytochemical studies found GPDH-positive reaction product only in morphologically identified oligodendrocytes, a result that is consistent with the previously reported localization of this enzyme in rat brain. Optic nerve cytosol fractions displayed substantial high-affinity binding of both dexamethasone (DEX) and corticosterone (CORT) that, like GPDH, was elevated approximately twofold in degenerating nerves. Finally, in vivo accumulation of [³H]DEX and [³H]CORT by optic nerve and other myelinated tracts was examined using nuclear isolation and autoradiographic methods. Although neither steroid was found to be heavily concentrated by these tissues in vivo , a small preference for DEX was observed in the nuclear uptake experiments. These results are discussed in terms of the hypothesis that glial cells are targets for glucocorticoid hormones.     

EFFECTS OF ICE ON ASCOPHYLLUM NODOSUM WITHIN THE GREAT BAY ESTUARY SYSTEM OF NEW HAMPSHIRE-MAINE12

The, effects of ice on Ascophyllum nodosum (L.) Le Jolis within the Great Bay Estuary System of New Hampshire-Maine, U.S.A. were assessed during the winter of 1980–81. Approximately 50% of the plants late fall standing crop, or an estimated 136 tonnes dry weight, was removed by ice-rafting. Pieces of Ascophyllum removed averaged 22 cm in length, 15 g in fresh weight and generally represented 2–3 years of growth. Although the winter of 1980–81 wax somewhat extreme, a similar pruning process probably occurs each year contributing to the characteristic bushy habit of attached inner estuarine plants. Ascophyllum fragments rafted in ice and deposited into salt marshes are suggested as a major source of the, ecad scorpioides (Hornemann) Hauck.