Mutants Defective in Binding Activity for Cyclic Adenosine 3′,5′-Monophosphate in Vibrio parahaemolyticus

Mutants of Vibrio parahaemolyticus defective in binding activity for adenosine 3',5'-cyclic monophosphate are described. They were selected with medium containing the nucleotide together with starch.     

Physicochemical analysis of (Pro-Pro-Gly)n with defined molecular weight--temperature dependence of molecular weight in aqueous solution

Sequenced polytripeptides, (Pro-Pro-Gly)_n, (n = 10, 15, 20), with defined molecular weights were synthesized by the solid-phase method. Conformational changes of these sample as a function of temperature were studied by measurements of optical rotation and sedimentation equilibrium. The temperature dependence of optical rotation was shown similar to thermal transition of collagen molecule. Each of these polymers existed as a timer at lower temperature. (Pro-Pro-Gly)₁₀ existed as a monomer at higher temperature, and the others were expected to behave analogously.     

Genetic studies in natural populations of forest trees

Summary The present study deals with the genetic differentiation within a natural forest of Cryptomeria japonica. Needle leaves were collected from approximately 50 trees in each of three sites, called subpopulations I, II and III, located at the apices of a triangle. The distances from each other among these three subpopulations were 760 m or 1,300 m. It was found, by an electrophoretic study of peroxidase, that the mean number of isozyme bands exhibited per individual tree was 11.68 in I, 13.73 in II and 12.53 in III. The t-test revealed that the differences between I and II and between II and III were statistically significant. The frequency of occurrence of each band was compared among the subpopulations. It was found that the variation among the three subpopulations was statistically significant. Not a few papers dealing with the study of pollen dispersal in coniferous trees have been published so far. Some of the authors consider that the distance of pollen dispersal is short and gene flow among subpopulations within a forest seldom occurs, while others are of the opinion that pollen travels long distances and no effective isolation is possible within a forest. Findings from the present study support the former view. They show that subpopulations within a forest of Cryptomeria japonica are genetically differentiated from each other, i. e. Sewall Wright's neighbourhood size is small in Cryptomeria japonica.

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Zusammenfassung Die vorliegende Arbeit befaßt sich mit der genetischen Differenzierung innerhalb eines natürlichen Waldbestandes von Cryptomeria japonica. Von drei als Subpopulation bezeichneten, in Dreiecksform angeordneten Standorten wurden Nadeln von jeweils etwa 50 Bäumen geerntet. Der Abstand der Sub-populationen voneinander betrug 760 bzw. 1300m. Mit Hilfe elektrophoretischer Untersuchung der Peroxydasen wurde gefunden, daß die durchschnittliche Zahl der Isozymbanden je Individuum 11.68 in I, 13.73 in II und 12.53 in III betrug. Der t-Test ergab eine signifikante Differenz zwischen I und II und zwischen II und III.Die Häufigkeit des Auftretens jedes Bandes wurde zwischen den Subpopulationen verglichen. Es wurde beobachtet, daß die Variation zwischen diesen drei Subpopulationen statistisch signifikant war.Es gibt nicht wenige Arbeiten, in denen über Untersuchungen zur Pollenverbreitung bei Koniferen berichtet wird. Einige der Autoren nehmen an, daß die Entfernung der Pollenverbreitung gering ist und daß der Genfluß zwischen Subpopulationen innerhalb eines Waldbestandes selten auftritt, während andere der Ansicht sind, daß Pollen über große Entfernungen verbreitet wird und eine wirksame Isolation innerhalb eines Forsts nicht möglich ist.Die Beobachtungen der vorliegenden Untersuchungen unterstützen die erste Ansicht. Sie zeigen, daß Subpopulationen innerhalb eines Waldbestandes von Cryptomeria japonica genetisch voneinander verschieden sind, d. h., daß Sewall Wright's Nachbarschaftsgröße bei Cryptomeria japonica klein ist.

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Contributions from National Institute of Genetics, Misima, No. 790.

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Researcher in Institute of Forest Genetics, Suwon, Korea, temporarily working in National Institute of Genetics, Misima.     

Biological features of the skin of the pika, Ochotona rufescens rufescens: histological structure and enzymatic histochemical reactivity

To examine the usefulness of the pika, Ochotona rufescens rufescens, as an experimental animal for skin irritability tests, the histological structure and enzymatic histochemical reactivity of pika skin were investigated. The pika had a hair cycle similar to that of the rabbit. The skin and epidermis of the pika trunk were 1.16mm and 29.5 microns thick, on the average, respectively. Both of them were the thickest in the dorsal region followed by the interscapular area, while they were the thinnest in the abdominal region. In the epidermis of the pika, the strata corneum, granulosum, spinosum and basale were rather clearly distinguished. The cell arrangement in the stratum basale was more compact than that in the rabbit. Dermal mast cells, which are distributed in the stratum reticulare in rabbits and guinea pigs, were distributed in the stratum papillare right beneath the epidermis. The mast cell of the pika in the TEM images had granules of low electron density and with relatively long microvilli and rather large mitochondria. The activities of the enzymes, SDH, MDH, LDH, beta HBDH, alpha GPDH, ALD, G6PDH and GPR, in the hair follicles and sebaceous glands of the pika were similar to those of the rabbit.     

Type VII collagen forms an extended network of anchoring fibrils

Type VII collagen is one of the newly identified members of the collagen family. A variety of evidence, including ultrastructural immunolocalization, has previously shown that type VII collagen is a major structural component of anchoring fibrils, found immediately beneath the lamina densa of many epithelia. In the present study, ultrastructural immunolocalization with monoclonal and monospecific polyclonal antibodies to type VII collagen and with a monoclonal antibody to type IV collagen indicates that amorphous electron-dense structures which we term "anchoring plaques" are normal features of the basement membrane zone of skin and cornea. These plaques contain type IV collagen and the carboxyl-terminal domain of type VII collagen. Banded anchoring fibrils extend from both the lamina densa and from these plaques, and can be seen bridging the plaques with the lamina densa and with other anchoring plaques. These observations lead to the postulation of a multilayered network of anchoring fibrils and anchoring plaques which underlies the basal lamina of several anchoring fibril-containing tissues. This extended network is capable of entrapping a large number of banded collagen fibers, microfibrils, and other stromal matrix components. These observations support the hypothesis that anchoring fibrils provide additional adhesion of the lamina densa to its underlying stroma.     

Type III collagen can be present on banded collagen fibrils regardless of fibril diameter

Monoclonal antibodies that recognize an epitope within the triple helix of type III collagen have been used to examine the distribution of that collagen type in human skin, cornea, amnion, aorta, and tendon. Ultrastructural examination of those tissues indicates antibody binding to collagen fibrils in skin, amnion, aorta, and tendon regardless of the diameter of the fibril. The antibody distribution is unchanged with donor age, site of biopsy, or region of tissue examined. In contrast, antibody applied to adult human cornea localizes to isolated fibrils, which appear randomly throughout the matrix. These studies indicate that type III collagen remains associated with collagen fibrils after removal of the amino and carboxyl propeptides, and suggests that fibrils of skin, tendon, and amnion (and presumably many other tissues that contain both types I and III collagens) are copolymers of at least types I and III collagens.     

Molecular Nature of Spontaneous Mutations in Mouse Lactate Dehydrogenase-a Processed Pseudogenes

The presence of at least ten mouse LDH-A pseudogenes was demonstrated in the genomic blot analysis, and four different processed pseudogenes have thus far been isolated and characterized. In this report, the nucleotide sequences to two different mouse lactate dehydrogenase-A processed pseudogenes, M11 and M14, were determined and compared with the protein-coding sequences of the mouse and rat LDH-A functional genes. In the pseudogene M11, the sequence of 64 nucleotides from codon no. 257 to 278 was tandemly duplicated. In the pseudogene M14, the sequence of 22 nucleotides from codon no. 68 to 75 was replaced by an inserted repetitive sequence of 242 nucleotides homologous to a mouse truncated R element. The pattern of nucleotide substitutions accumulated in mouse LDH-A pseudogenes M11 and M14, as well as that of pseudogene M10 identified previously, was analyzed, and the substitution frequencies of the C or G at the CG dinucleotide were found to be high.     

Experimental allergic encephalomyelitis mediated by murine encephalitogenic T cell lines specific for myelin proteolipid apoprotein

T cell lines specific for bovine myelin proteolipid apoprotein (PLP) were established from SJL/J mice. The line cells bore surface phenotypes of T helper/inducer cells (Lyt-1+, Lyt-2-, L3T4+) and responded well to bovine, rat, and guinea pig PLP but not to myelin basic protein. One line responded to major PLP, and another responded to both major PLP and DM-20, which are the two major intrinsic membrane proteins of the central nervous system (CNS) myelin. Intraperitoneal inoculation of 4 to 30 X 10(6) PLP-activated line cells followed by injection of pertussis vaccine induced acute inflammatory disease of the CNS, with typical clinical signs of EAE mostly in a week in recipient mice that had been treated with low-dose irradiation. Almost all animals recovered completely, and two of the 12 animals relapsed 42 or 75 days after inoculation. The lesions were restricted to the CNS and were characterized by perivascular and parenchymal infiltration of inflammatory cells, fibrin deposit, and demyelination. In the severe lesions, axons were also damaged. These observations suggest that PLP is a definite encephalitogen, and PLP-sensitized effector T cells induce inflammatory demyelination in the CNS.     

Antimutagenicity of extracts from crude drugs in Chinese medicines

The antimutagenicity of extracts from crude drugs was studied by the Ames bioassay system. The crude drugs chosen were medical plants used very frequently as Chinese medicines. Each crude drug was extracted with hot water similar to the method of Chinese medical treatment. Antimutagenicity of the extract was found with 4 kinds of crude drugs, Paeoniae radix, Bupleuri radix, Hoelen and Glycyrrhizae radix. Each extract of the crude drug showed a different type of antimutagenic action from the others.     

A quantitative study of synaptic ribbons in pinealocytes of adult Chinese hamsters (Cricetulus griseus) under different photoperiodic conditions

Summary Synaptic ribbons (SR) in pinealocytes of adult (120–130 day-old) male Chinese hamsters (Cricetulus griseus) were classified into types 1, 2 and 3; these have a central dense structure showing rod-like, various and ringlike profiles, respectively. The central structure of the type-2 SR usually appeared as round, oval or comma-like bodies, and occasionally as plates showing various profiles or clubshaped bodies. The quantity of each type of SR, expressed as the SR index, was determined over a 24-h period under a light/dark regime (LD) 1212 or LD 1410. On comparing the results obtained from adults with previously published data from young (60–70-days-old) animals under LD 1212, it was found that, in both young and adult animals, the type-1 and type-3 SR indices exhibited different 24-h variations, whereas the type-2 SR index remained constant over a 24-h period. In addition, the indices of the type-2 SR, but not those of the other SR types, were found to be significantly larger in adult than in young animals. In adult animals, the effects of the photoperiod were different between the three types of SR. A nocturnal increase in the type-1 SR index was observed under both LD 1212 and LD 1410, its time course being different for each of these photoperiods. Under LD 1410, the type-2 SR index showed a significant 24-h rhythm with larger values during the dark period; this was not observed under LD 1212. The type-3 SR index was almost the same under LD 1212 and LD 1410. The results suggest that pinealocyte SR of the Chinese hamster may be composed of three types of SR, each with a different functional role.