Progesterone interaction with estrogen and antiestrogen in the rat uterus--receptor effects.

Daily injections of estradiol or the antiestrogen tamoxifen initially stimulate uterine weight increase and progesterone receptor synthesis, though continued tamoxifen fails to maintain the increased weight. The stimulatory actions of both estradiol and tamoxifen are inhibited or reversed by a single injection of progesterone. It has been hypothesized that progesterone antagonizes estrogen action by reducing estrogen receptor levels, but in the present experiments neither cytoplasmic nor nuclear estrogen receptor was affected. We conclude that progesterone acts at a point beyond estrogen receptor availability or translocation to antagonize estrogen action.     

1H-nmr study on the preferred conformations of chiral pyridine-dinucleotide models

The synthesis of four chiral NAD⁺ models 1 and their 1,4-dihydro analogs 2 is described. From the temperature dependence of the ¹H-nmr spectra it is concluded that for these compounds two preferred conformations I and II, differing slightly in energy, exist. Both conformations are “folded” with the more or less parallel p-anisyl and pyridine groups mutually gauche, but in I the pyridine group is rotated by about 180° as compared with II, thus leading to a conspicuous difference in orientation of the substituent Z (NH₂CO, C₆H₅NHSO₂, (CH₂)₄NSO₂, or (C₄H₈ON)SO₂) in the pyridine ring toward the anisyl group. The most stable conformation (I) has Z closest to the center of the p-anisyl group. In 360-MHz spectra of the dihydropyridines at low temperature (?10°C), slow interconversion of I and II leads to the observation of an XY pattern for the C-4 methylene protons of the 1,4-dihydropyridine system. The anisochronity in this methylene group is caused mainly by the anisotropy of the neighboring p-anisyl group.     

Postsynaptic membranes in the electric tissue of Narcine: II. A freeze-fracture study of nicotinic receptor molecules

The ventral, postsynaptic membranes of the electroplaques of Narcine were found to containe intramembranous particles similar in location, packing density (about 5700/micron 2), transmembrane position and end appearance to nicotinic acetylcholine receptor-channel molecules. In fixed tissue the particles were limited to the cytoplasmic lamina, while in unfixed tissue an equivalent number were found symmetrically in both laminae. Four populations of particle diameters were observed in each unfixed lamina, even though other morphological evidence indicates the presence of large number of molecules of uniform structure, and biochemical studies of isolated postsynaptic membranes indicate that at least 70% of the membrane protein is receptor-channel protein. Intramembranous particles in dorsal, non-innervated electroplaque membranes, presumably representing Na+, K+-associated ATPase and other channel proteins, were found to have similar characteristics to particles in ventral membranes. Receptor-channel molecules cannot, therefore, be distinguished from other intrinsic membrane proteins by freeze-replication alone.     

Protein intake regulation in the weanling rat: Effects of additions of lysine,arginine and ammonia on the selection of gluten and energy

The effects of adding lysine, arginine and ammonia to gluten on the self-selection of protein and energy by the weanling rat simultaneously offered a choice of two diets differing only in gluten concentration (15 and 55%) were tested. Previous studies have shown that while lysine (6 g/100 g) additions to gluten decreased the amount of gluten selected by the rat from 40 to 20 g per 100 g of food eaten, selection was not related to the nutritional quality of the gluten. When graded levels of arginine (1.8, 3.6 or 7.2 g/100 g) were added to the gluten with or without lysine (0 or 6 g/100 g) the dietary protein selection was unaffected. The addition of ammonia (1.4 g/100 g as NH₄Cl) to gluten had initially the same effect as lysine (6 g/100 g) but with time protein intake returned to control levels. This effect of ammonia was unaltered by arginine additions. It is concluded that the mechanisms which lead to decreases in gluten selection caused by lysine or ammonia are not similar, and that the effects of lysine on gluten selection are not caused by an increased arginine requirement for urea cycle activity.     

Ein Endemit Zyperns:Asperula cypria (Rubiaceae) und seine Verwandtschaft

Galium suberosum Sibth. etSm. belongs toAsperula sect.Thliphthisa; the taxonomic transfer and a new name are therefore necessary:Asperula cypria Ehrend. is endemic on the isle of Cyprus. Its closest affinities are withA. antalyensis Ehrend. in S.W. Anatolia.

     

Revision der GattungLoxonia (Gesneriaceae)

Within the genusLoxonia Jack, currently regarded as monotypic, three species are recognized:L. hirsuta Jack (Sumatra, Mentawai-Islands, Java, Borneo, Anambas-Islands, Malay Peninsula),L. discolor Jack (Sumatra) andL. burttiana A. Weber, spec. nova (Borneo). [Key with English translation p. 203.] There is evidence thatL. discolor is the most primitive species within the genus, the two others being derived from it.

Teil V der Beiträge zur Morphologie und Systematik derKlugieae undLoxonieae (Gesneriaceae).     

Crystallographic data on a complete kappa-type human Bence-Jones protein.

A complete human κ-type Bence—Jones protein (Fin) has been isolated and crystallized. Immunochemical and physicochemical characterization of protein Fin indicates that it is of the κ-chain subgroup, κII, and that it consists of two non-covalently bound intact monomers having a molecular weight of ~23,000 Crystals of Bence—Jones protein Fin obtained from ammonium sulfate solutions have the orthorhombic space group P2₁2₁2₁ with cell dimensions $\text{a = 132.0}\text{A}\text{?}\text{, b = 93.3}\text{A}\text{?}\text{, and}\text{c = 42.3}\text{A}\text{?}$. The asymmetric unit consists of a dimer of molecular weight ~46,000.     

Identification and restriction endonuclease mapping of the threonine operon regulatory region.

A DNA fragment carrying the thrP region of Escherichia coli has been identified and characterized. Starting from a secondary site lysogen of bacteriophage λ, where the position of the prophage is either within thrP or between thrP and thrP structural genes (Gardner et al., 1974; Gardner &; Smith, 1975) it has been possible to isolate transducing phages which carry bacterial DNA from either side of the prophage. By Int-Xis mediated site-specific recombination we have generated recombinant transducing phages which carry an intact thrP region. A phage carrying a regulatory mutation, which maps in the thrP region, has also been constructed.Mapping with several restriction endonucleases has allowed us to construct a map of the cleavage sites of the thrP region. A 1700 base-pair HaeIII fragment carrying the secondary attachment site (attΔOΔ′) was isolated and its position was localized within a 180 base-pair TaqI-HhaI restriction fragment. The location of attΔOΔ′ in the HaeIII fragment suggests that the entire thrP region is carried by this fragment.     

BENTHIC MARINE DIATOM ASSOCIATIONS: UPPER FLORIDA BAY (FLORIDA) AND ASSOCIATED SOUNDS1

Models of the diatom associations found in upper Florida Bay and adjoining sounds have been constructed utilizing Q modal factor-vector analysis and ecologic diversity indices (Shannon index, number of species, evenness). Four distinct associations were defined using Q-mode factor-vector analysis. Two associations were epiphytic, occurring on Thalassia testudinum König—Association I was characterized by Cocconeis placentula Ehr., Association III by Cylindrotheca closterium (Ehr.) Reim. & Lewin and Cocconeis placentula Ehr. The other two associations were epipelic, occurring on the carbonate mud substratum—Association II was characterized by Cyclotella striata (Kütz.) Grun., Rhopalodia gibberula (Ehr.) O. Müller and Surirella fastuosa (Ehr.) Kütz., Association IV by Fragilaria crotonensis Kitton and Cyclotella striata (Kütz.) Grun. The majority of the 161 species identified were present in both the epiphytic and epipelic assemblages. Only 33 species were restricted to the epiphyton, and 18 species restricted to the epipelon. The epipelic assemblage was significantly more diverse than was the epiphytic assemblage. A general trend of increased diversity away from terrestrial environs toward more open areas of water in both the epipelon and epiphyton was also found.     

STUDIES OF HAWAIIAN FRESHWATER AND SOIL ALGAE II. ALGAL COLONIZATION AND SUCCESSION ON A DATED VOLCANIC SUBSTRATE1,2

Spatial studies of colonization and succession of soil algae and chemical analyses of the various soils on the cinde cone of Kilauea Iki in Hawaii Volcanoes National Park, Hawaii are outlined. There is a positive correlation between the diversity and quantity of soil algae with nutrient levels and organic matter accumulation in each locale. Three distinct edaphic-biotic zones existing in this area are differentially revealed by the soil chemical composition, quantity and diversity of soil algae, and as evident variations in higher plant growth and colonization. Varying colonization and successional phases of higher plant growth around standing and fallen tree snags killed by volcanic activity also reflect variations in the soil algal flora. These variations appear largely as a function of differential water interception, absorption, and retention as well as differential accumulation of organic matter, and the initiation of various biogeochemical cycles.