Kinetic properties of bovine brain proteinl-isoaspartyl methyltransferase determined using a synthetic isoaspartyl peptide substrate

Proteinl-isoaspartyl methyltransferase, an enzyme enriched in brain, is implicated in the repair of age-damaged proteins containing atypical, isoaspartyl peptide bonds. We have investigated the kinetics of methylation using a synthetic peptide substrate having the structure Trp-Ala-Gly-Gly-isoAsp-Ala-Ser-Gly-Glu. Double-reciprocal plots of initial velocity versus concentration of S-adenosylmethionine (AdoMet) at different fixed concentrations of peptide gave straight lines converging at a positive 1/v value and a negative 1/AdoMet value. The product S-adenosylhomocysteine (AdoHcy) was a competitive inhibitor towards AdoMet and a linear mixed-type inhibitor towards peptide. These results are consistent with the rapid-equilibrium random sequential bi-bi mechanism previously proposed for the enzyme, but they also reveal the formation of the deadend, enzyme-peptide-AdoHcy, complex. The rate constants were:V _max=32–34 nmol/min/mg,K ^peptide=7.6–9.4 M,K ^AdoMet=1.9–2.2 M, =0.43–0.53,K ^AdoHcy=0.08 M, =2.9. The interaction factors and indicate that binding of enzyme to peptide increases its affinity for AdoMet and decreases its affinity for AdoHcy. Methylation was linear with time throughout the transfer of 2 mol of methyl groups/mol of enzyme. This absence of burst kinetics suggests that slow release of products cannot explain the low turnover number.Special issue dedicated to Dr. Paul Greengard     

A case of hereditary persistence of fetal hemoglobin caused by a gene not linked to the β-globin cluster

Summary The pattern of inheritance of several polymorphic restriction sites associated with the -gene cluster, and spanning a region of 52 kb, demonstrates that a determinant for hereditary persistence of fetal hemoglobin (HPFH) segregates independently from the non- globin gene cluster, as we postulated several years ago on purely genetical grounds. This finding provides additional evidence for the existence of diffusible factors affecting -chain expression. Moreover, we have identified a private HinccII polymorphism, in the vicinity of the gene in the family studied.     

Biological and physico-chemical properties of an atypical mutant of tobacco mosaic virus

Summary A mutant of tobacco mosaic virus (TMV) was isolated from a population of TMV-RNA molecules inactivated to 0.1% level of survival by treatment with nitrous acid This mutant is poorly transported in Samsun tobacco and induces chlorotic spots, oak-leaf patterns, ringspots and necrosis. Rate zonal sucrose density-gradient and equilibrium sedimentations in sucrose and CsCl indicate that the purified mutant preparations contain a heterogenous population of particles including some free coat protein. These vary in length, but approximately 5–10% are infectious rods of standard (15×300 nm) dimensions. Purified mutant RNA contain an overabundance of fragmented and a few infectious molecules. Compared to the parent strain, the mutant capsid protein contains two additional residues of arginine and one of glycine, but lacks one residue each of glutamic acid (or glutamine), serine and threonine. These observations and other data based on temperature sensitivity, exposure to urea and serology indicate that the mutant particles are inherently unstable and break during the purification procedure.     

Ultrastructure of Sporothrix schenckii treated with iodine-potassium iodide solution

The ultrastructural changes produced by iodine-potassium iodide solution on yeast cells of Sporothrix schenckii were investigated by transmission electron microscopy in order to clarify the mechanism of oral potassium iodide therapy for sporotrichosis. Yeast cells were dipped with solutions containing various concentrations of iodine. The rate of germination decreased markedly between the range of iodine concentrations from 0.63 g/ml to 5.0 g/ml. No significant ultrastructural changes were seen at the concentration of the iodine of 1.25 g/ml (80% germination) or less. In the concentration of 2.5 g/ml (50% germination), normal cells and degenerated cells coexisted. When the cells were treated with 5.0 g of iodine per ml (0% germination) or more, their interior structures were completely destroyed. It is assumed that iodine treatment of the organism causes rapid destruction in the whole cell.     

Relation between trace element levels in plasma and myocardium during coxsackievirus B3 myocarditis in the mouse

During most infections the plasma levels of trace elements change, but it is not clear if this reflects changes in the infected tissues. Coxsackievirus B3 (CB3) infection may result in viral replication, subsequent inflammation and changed trace element levels in the myocardium. In the present study, the trace element levels in the plasma and heart of adult male A/J mice were determined during the pre-inflammatory stage (day 4) of CB3 myocarditis for the following trace elements: aluminium (Al), arsenic (As), calcium (Ca), cobalt (Co), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), selenium (Se), silver (Ag), vanadium (V) and zinc (Zn). The severity of the infection was assessed through clinical signs of disease and trace element levels were measured through inductively-coupled plasma mass-spectrometry (ICP-MS). In the heart, the levels decreased for V (59%; p<0.01), Co (38%; p<0.01), Al (81%; p< 0.01), As (66%; p<0.01) and Se (16%; p<0.01). Increased levels were detected for Mn (13%; p<0.05), Fe (48%; p<0.01), Cu (34%; p<0.01) and Ag (46%; p< 0.01). In the plasma, decreases were detected in the level of Zn (32%; p<0.05), whereas increases were seen in Mn (362%; p<0.05), Fe (272%; p<0.01), Co (71%; p<0.05), Cu (25%; n.s.) and Mg (43%; p<0.01) levels. A correlation was found between the levels in plasma and myocardium for Co (r _s=–0.636; p<0.05), Fe (r _s=0.764; p<0.05), Mn (r _s=0.682; p<0.05) and Mg (r _s=–0.791; p<0.05). Thus, determination of some of these trace elements in the plasma may be useful to indicate target tissue involvement in the early pre- inflammatory stage of an infectious disease. Some of these elements are important nutrients for the immune system, while others may be associated with the development of disease complications, such as cardiac arrhythmias.     

Subtle behavioral variation in wild chimpanzees, with special reference to Imanishi’s concept of kaluchua

Here we consider the concept of kaluchua (a word adopted from the English culture) in group-living animals developed by Imanishi in the 1950s. He distinguished it from bunka (the Japanese equivalent to the English culture) because he thought that bunka had strong connotations of noble and intellectual human-like activities. Although he did not rigidly define kaluchua, his original concept of kaluchua was much broader than bunka and represented non-hereditary, acquired behavior that was acknowledged socially. However, instead of social life, complex feeding skills have often formed the central topic in the current studies of animal culture. In order to provide evidence that more subtle behavioral variations exist among wild chimpanzee (Pan troglodytes) populations, we directly compared the behaviors of two well-habituated chimpanzee groups, at Bossou and Mahale. During a 2-month stay at Bossou, M.N. (the first author) saw several behavioral patterns that were absent or rare at Mahale. Two of them, mutual genital touch and heel tap were probably customary for mature females and for mature males, respectively. Index to palm and sputter are still open to question. These subtle patterns occurred more often than tool use during the study period, suggesting that rarity is not the main reason for their being ignored. Unlike tool use, some cultural behavioral patterns do not seem to require complex skills or intellectual processes, and sometimes it is hard to explain the existence of such behaviors only in terms of function.     

Pheromone puffs suppress mating by Plodia interpunctella and Sitotroga cerealella in an infested corn store

The efficacy of pheromone mating disruption was investigated in a 7×6×3 m corn storage room harboring a high population density of Indian meal moth, Plodia interpunctella (Hübner) and Angoumois grain moth, Sitotroga cerealella (Olivier). Pheromones were released from a controlled release dispenser, the metered semiochemical timed release system (MSTRS^TM) at emission rates of 0.6 g min^–1 (Z9,E12:14:Ac for Indian meal moth) and 0.2 g min^–1 (Z7,E11-16:Ac for Angouimois grain moth). Mating disruption efficacy was evaluated using three parameters: male capture in pheromone traps, visual examination of mating behavior, and the incidence and frequency of mating as measured by spermatophores. In three trials, comparisons were made between data collected before pheromone treatment and during treatment. Disruption of pheromone source location by males averaged 70% and 40% for P. interpunctella and S. cerealella, respectively, in the three trials. In addition, reduced levels of copulation by both species were recorded during pheromone treatment. More importantly, significant reductions were recorded in the incidence and frequency of mating by females of both species collected during the treatment period. While 85% of P. interpunctella females collected before pheromone treatment in three trials had mated at least once, only 50% of the females collected during treatment had mated. The mean number of matings, as measured by spermatophores, ranged between 0.8–1.1 and 0.5–0.7 before and during pheromone treatment, respectively. Similarly, a 20–30% reduction in the proportion of mated S. cerealella females was recorded during pheromone treatment. In the three trials, mean number of spermatophores per S. cerealella female averaged 1.0 and 0.7 during the pretreatment and treatment periods, respectively. Additional tests conducted in small boxes also recorded significant mating disruption of both species.     

The neutral carotenoids of wild-type and mutant strains of Neurospora crassa

The neutral carotenoids of wild-type Neurospora crassa and of carotenoid mutants at four discrete genetic loci were isolated using gradient elution chromatography on deactivated alumina columns. Carotenoids were identified by absorption spectrophotometry and thin layer cochromatography with carotenoid standards. Phytoene, phytofluene, -carotene, -carotene, neurosporene, torulene, lycopene, and 3,4-dehydrolycopene were isolated from wild type. Phytoene, phytofluene, -carotene, -carotene, neurosporene, -carotene, lycopene, and one unknown carotenoid, tentatively identified as 15,15-cis--carotene, were isolated from a yellow mutant, ylo-1. ylo-1 also contained residual carotenoids having similar absorption spectra to, but very different chromatographic behavior from, phytofluene, -carotene, -carotene, and lycopene. Albino and colored al-1 mutants contained large amounts of phytoene and only traces of other neutral carotenoids. Albino al-2 and al-3 mutants contained only traces of neutral carotenoids.     

Testis-specific β2 tubulins are identical in Drosophila melanogaster and D. hydei but differ from the ubiquitous β1 tubulin

In Drosophila as in many organisms tubulins are encoded by a gene family. We have determined the complete nucleotide sequences coding for the 1 and 2 tubulins of Drosophila melanogaster and the 2 tubulin of D. hydei, and found these insect tubulins to be highly conserved and like tubulins of other organisms. This is discussed with reference to the possible functional domains of these proteins. — The 1 tubulin gene of Drosophila is constitutively expressed, whereas the 2 tubulin is expressed specifically in the testes. In D. melanogaster the amino acid sequences of these proteins are 95% homologous, differing at only 25 positions. In the testes the 2 tubulin participates in different microtubules as shown by genetic analysis (Kemphues et al. 1982). Interestingly, all of the amino acids characteristic of the testis-specific 2 tubulin are also present in the corresponding gene of D. hydei. Of special interest is the high degree of conservation of the carboxy-terminal domain in these functionally equivalent tubulins.     

Cholinesterases and cell proliferation in “nonstratified” and “stratified” cell aggregates from chicken retina and tectum

Summary Dissociated single cells from chicken retina or tectum kept in rotation-mediated cell culture aggregate, proliferate and establish a certain degree of histotypical cellto-cell relationships (sorting out), but these systems never form highly laminated aggregates (nonstratified R- and T-aggregates). In contrast, a mixture of retinal plus pigment epithelial cells forms highly stratified aggregates (RPE-aggregates, see Vollmer et al. 1984). The present comparative study of stratified and nonstratified aggregates enables us to investigate the process of cell proliferation uncoupled from that of tissue stratification. Here we try to relate these two basic neurogenetic processes with patterns of expression of cholinesterases (AChE, BChE) during formation of both types of aggregates.During early aggregate formation, in both stratified and nonstratified aggregates an increased butyrylcholinesterase activity is observed close to mitotically active cells. Quantitatively both phenomena show their maxima after 2–3 days in culture. In contrast, AChE-expression in all systems increases with incubation time. In nonproliferative areas, in the center of RPE-aggregates, the formation of plexiform layers is characterized initially by weak BChE and then strong AChE-activity. These areas correspond with the inner (IPL) and outer (OPL) plexiform layers of the retina in vivo. Although by sucrose gradient centrifugation we find that the 6S- and the fiber-associated 11S-molecules of AChE are present in all types of aggregates, during the culture period the ratio of 11S/6S-forms increases only in RPE-aggregates, which again indicates the advanced degree of differentiation within these aggregates.It is thus demonstrated that cholinesterases first correlate with neuronal cell proliferation and later with stratification, which indicates functions of both enzymes during both developmental periods.Abbreviations AChE acetylcholinesterase - BChE butyrylcholinesterase - iso-OMPA specific inhibitor of BChE - BW 284C51 specific inhibitor of AChE - IPL inner plexiform layer - OPL outer plexiform layer     

Recruitment Behavior in the Ant Genus Polyrhachis (Hymenoptera, Formicidae)

We present a detailed behavioral analysis of the signals involved in recruitment of 11 syntopic Polyrhachis species from West Malaysia. We found a considerable variety of recruitment techniques, including social carrying behavior, tandem running, group recruitment, and a technique which we call leader-independent trail communication. The latter mode superficially resembles chemical mass communication (sensu Wilson, 1962). All these recruitment techniques involve mechanical invitation behavior inside the nest, comprising back-and-forth jerking or pulling movement often combined with a sideways waggling. However, not in all cases of leader-independent trail communication is a mechanical invitation behavior obligatory. The trail pheromone of all investigated Polyrhachis species originates from the hindgut. Only in the tandem running P. proxima do additional secretions from the poison gland appear to be involved in tandem calling.     

Synthesis of Aminoethyl Glycosides of the Ganglioside GM1 and Asialo-GM1 Oligosaccharide Chains

4-O-Glycosylation of 2-azidoethyl 2,3,6-tri-O-benzyl-4-O-(2,3-di-O-benzyl-6-O-benzoyl--D-galactopyranosyl)--D-glucopyranoside with a disaccharide donor, 4-trichloroacetamidophenyl 4,6-di-O-acetyl-2-deoxy-3-O-(2,3,4,6-tetra-O-acetyl--D-galactopyranosyl)-1-thio-2-trichloroacetamido--D-galactopyranoside, in dichloromethane in the presence of N-iodosuccinimide and trifluoromethanesulfonic acid resulted in a tetrasaccharide, 2-azidoethyl (2,3,4,6-tetra-O-acetyl--D-galactopyranosyl)-(1 3)-(4,6-di-O-acetyl-2-deoxy-2-trichloroacetamido--D-galactopyranosyl)-(1 4)-(2,3-di-O-benzyl-6-O-benzoyl--D-galactopyranosyl)-(1 4)-2,3,6-tri-O-benzyl--D-glucopyranoside, in 69% yield. The complete removal of O-protecting groups in the tetrasaccharide, the replacement of N-trichloroacetyl by N-acetyl group, and the reduction of the aglycone azide group to amine led to the target aminoethyl glycoside of -D-Gal-(1 3)--D-GalNAc-(1 4)--D-Gal-(1 4)--D-Glc-OCH₂CH₂NH₂ containing the oligosaccharide chain of asialo-GM₁ ganglioside in 72% overall yield. Selective 3-O-glycosylation of 2-azidoethyl 2,3,6-tri-O-benzyl-4-O-(2,6-di-O-benzyl--D-galactopyranosyl)--D-glucopyranoside with thioglycoside methyl (ethyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-2-thio-D-glycero--D-galacto-2-nonulopyranosyl)oate in acetonitrile in the presence of N-iodosuccinimide and trifluoromethanesulfonic acid afforded 2-azidoethyl [methyl (5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero--D-galacto-2-nonulopyranosyl)oate]-(2 3)-(2,6-di-O-benzyl--D-galactopyranosyl)-(1 4)-2,3,6-tri-O-benzyl--D-glucopyranoside, the selectively protected derivative of the oligosaccharide chain of GM₃ ganglioside, in 79% yield. Its 4-O-glycosylation with a disaccharide glycosyl donor, (4-trichloroacetophenyl-4,6-di-O-acetyl-2-deoxy-3-O-(2,3,4,6-tetra-O-acetyl--D-galactopyranosyl) 1-thio-2-trichloroacetamido--D-galactopyranoside in dichloromethane in the presence of N-iodosuccinimide and trifluoromethanesulfonic acid gave 2-azidoethyl (2,3,4,6-tetra-O-acetyl--D-galactopyranosyl)-(1 3)-(4,6-di-O-acetyl-2-deoxy-2-trichloroacetamido--D-galactopyranosyl)-(1 4)-{[methyl (5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero--D-galacto-2-nonulopyranosyl)onate]-(2 3)}-(2,6-di-O-benzyl--D-galactopyranosyl)-(1 4)-2,3,6-tri-O-benzyl--D-glucopyranoside in 85% yield. The resulting pentasaccharide was O-deprotected, its N-trichloroacetyl group was replaced by N-acetyl group, and the aglycone azide group was reduced to afford in 85% overall yield aminoethyl glycoside of -D-Gal-(1 3)--D-GalNAc-(1 4)-[-D-Neu5Ac-(2 3)]--D-Gal-(1 4)--D-Glc-OCH₂CH₂NH₂ containing the oligosaccharide chain of GM₁ ganglioside.     

The filtration apparatus of Cladocera: Filter mesh-sizes and their implications on food selectivity

Summary The filtering apparatus of eleven Cladoceran species was studied. The distances between the setulae, which act as filters, were measured. Among adult individuals, they vary from 0.2 m in Diaphanosoma brachyurum to 4.7 m in Sida crystallina. Species can be grouped according to the mesh-sizes, as fine mesh filter-feeders: Diaphanosoma brachyurum, Ceriodaphnia quadrangula, Chydorus sphaericus, Daphnia cucullata and Daphnia magna; medium mesh filter-feeders: Daphnia galeata, D. hyalina. D. pulicaria, Bosmina coregoni, and coarse mesh filter-feeders: Holopedium gibberum and Sida crystallina. In Daphnia hyalina, the distances between setulae increase from 0.3–0.4 m in small juveniles, to 0.8–2.0 m in adults. In Daphnia magna, the mesh-size of the filter does not increase significantly with growth. There is good evidence that the relative abundance of the filter-feeding types varies with the trophic state of the lake. In oligotrophic lakes the coarse mesh filter-feeders usually dominate throughout the year. The seasonal succession of zooplankton species in eutrophic lakes can be interpreted as a succession of feeding types; during winter coarse mesh filter-feeders dominate, while fine mesh filter-feeders are most abundant during summer phytoplankton blooms. Our results support the hypothesis that the species composition of filter-feeding zooplankton is strongly influenced by the amount of suspended bacteria which are available as food only for filter-feeding species with fine meshes.     

Die Hemmung der Phytochrominduzierten Photomorphogenese („Positive” Photomorphosen) des Senfkeimlings (Sinapis alba L.) Durch Actinomycin D und Puromycin

Zusammenfassung Die positiven Photomorphosen Öffnung des Hypokotylhakens und Entfaltung der Kotyledonen können ganz ähnlich wie die phytochrominduzierte Anthocyansynthese und andere positive Photomorphosen durch Actinomycin D und Puromycin gehemmt werden. Man kann daraus schließen, daß diese beiden photomorphogenetischen Reaktionen des Senfkeimlings ebenfalls durch eine von P₇₃₀ über eine Signalkette ausgelöste Aktivierung von potentiell aktiven Genen veranlaßt werden.

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The inhibition of phytochrome-mediated photomorphogenesis (positive photoresponses) by actinomycin D and puromycin in the mustard seedling (Sinapis alba L.)

Summary The many photochrome-mediated photoresponses of a seedling (Sinapis alba L., white seeded mustard) can be divided into 3 categories: positive, negative, and complex photoresponses. Positive photoresponses are those which are characterized by an initiation or a promotion of biosynthetic or growth processes (Mohr, 1966b). Phytochrome-mediated anthocyanin synthesis is the prototype of a positive photoresponse. It has been shown in previous papers (e.g. Lange and Mohr, 1965; Mohr et al., 1965) that positive photoresponses can be specifically inhibited by actinomycin D and puromycin. It has been concluded that in the case of positive photoresponses P₇₃₀ (the active phytochrome) exerts its function through differential gene activation.—In the present paper it has been demonstrated that phytochrome-mediated positive photoresponses of the mustard seedling like opening of the hypocotylar hook and unfolding of the cotyledons can be inhibited by relatively low doses of actinomycin D and puromycin in very much the same way as anthocyanin synthesis or cotyledon enlargement is inhibited. It has been concluded that in these cases too the action of P₇₃₀ must be attributed to an activation of potentially active genes in the manner postulated on the basis of the data on anthocyanin synthesis.

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Die Arbeit wurde durch Sachbeihilfen der Deutschen Forschungsgemeinschaft und der Stiftung Volkswagenwerk (an Prof. Mohr) ermöglicht.     

Orientation of the porphyrin ring in artificial chlorophyll membranes

Summary A sensitive photometric method is described by which the dichroism of lipid bilayer membranes in aqueous phase can be measured. The method is applied to black films with incorporated chlorophylla andb. With chlorophylla a relatively large dichroism is found in the Soret band and a much weaker dichroism in the red band. From the experimental data, the angles _B and _R between the blue and red transition moments and the membrane can be obtained. _B and _R are then used to calculate the angle of the porphyrin ring with respect to the membrane surface. For chlorophylla and three different lipids, values of between 44 and 49° are found.     

<Emphasis Type="Italic">In vitro</Emphasis> screening of sugarcane to evaluate smut susceptibility

Tissue-cultured plantlets of three sugarcane (Saccharum spp.) cultivars having a known field smut reaction were screened for susceptibility to Ustilago scitaminea H&P Sydow. Plantlets were inoculated with 0.5 l of a suspension of equally mixed quantities of plus and minus mating type sporidia of U. scitaminea at concentrations ranging from 1×10¹ to 1×10⁶ cells. Fungal sori (whips) were produced in cultivar N12 (intermediate) 6weeks following inoculation with 1×10⁵ mixed sporidia and thereafter in cultivar NCo310 (susceptible) but not in cultivar N19 (resistant). Sori bearing teliospores were produced up to 3months following inoculation and incubation at 26°C. No sori were produced at mixed sporidial concentrations lower than 1×10⁵cells. The in vitro soral production in cultivars N19, N12 and NCo310 was 0, 27.5 and 47.5% respectively. Plantlets inoculated with 1×105sporidia of only one mating-type did not produce sori in any of the three cultivars tested. Blind scoring of an unknown sugarcane cultivar by this method corresponded exactly with its field smut rating.     

Selective amidation of carboxyl groups of the intermolecular contact regions of hemoglobin S: Structural aspects

Carboxyl groups of HbS are readily activated by water-soluble carbodiimide atpH 6.0 and room temperature. These o-acylurea intermediates (activated carboxyl) are accessible for nucleophilic attack by amines. With glycine ethyl ester, the amidation is very selective for the -carboxyl of Glu-43() and more than 65% of the glycine ethyl ester incorporated is on this carboxyl group. In contrast, glucosamine derivatizes the -carboxyl group of Glu-22() as well as that of Glu-43() to nearly the same degree. However, the total amidation of HbS by glucosamine is lower than that with glycine ethyl ester. The differential selectivity of the two amines is apparently related to the differences in the microenvironment of the -carboxyl groups of Glu-22() and Glu-43(), which either facilitates or refracts the aminolysis of the activated carboxyl with the two amines to different degrees. The carboxyl groups of isolated -chain exhibit a higher reactivity for amidation with glycine ethyl ester than does the tetramer. The carboxyl groups of Glu-22() and Glu-43() and that of Asp-47() are all activated by carbodiimide suggesting that the higherpK_a of these carboxyl groups (facilitating the activation) is a property of tertiary interaction of the polypeptide chain. The interaction of the -chain with -chain, i.e., generation of the quaternary interactions, reduces overall reactivity of the carboxyl groups of the protein. The higher selectivity of hemoglobin S for amidation at Glu-43() with glycine ethyl ester compared with that of isolated -chain appears to be primarily a consequence of decreased amidation at sites other than at Glu-43().     

The hypothalamo-hypophysial system in acipenseridae

Summary The neurohypophysis of sexually mature male and female Acipenser güldenstädti Brandt and Acipenser stellatus Pallas was studied light and electron microscopically. The recessus hypophysei lined with ependymal cells of two main types, narrow and wide, are in the center of the neurohypophysial roots. Processes from both cell types run radially to the basement membrane of the connective tissue layers abutting on the hypophysial intermediate lobe. Protrusions penetrating deep into the recessus hypophyseus are found in the apical parts of the wide cells. Pituicytes are rare in the neurohypophysis. The ultrastructure of both ependymal cell types and of the pituicytes is described. Nonmyelinated Gomori-positive (peptidergic) neurosecretory A₁ and A₂ type fibres and their terminals containing elementary neurosecretory granules (1400–1800 Å and 1000–1400 Å respectively) are the main structural elements of the neurohypophysis. Some dark and single myelinated neurosecretory fibres have been found. The adrenergic fibres (type B) were described earlier (Polenov et al., 1972a). The structural peculiarities of the neurohypophysis are discussed in functional and comparative-morphological terms.     

A novel missense mutation in the thyroid hormone receptor β gene in a kindred with resistance to thyroid hormone

Direct sequencing of exon 9 of the thyroid hormone receptor (TR) gene in a kindred with resistance to thyroid hormone revealed a substitution of threonine for methionine in codon 313 in one allele resulting from a T to C transition. This is a novel missense mutation that resides in one of the two mutational hot-spot regions of the TR gene suggesting altered triiodothyronine binding to this mutant receptor.     

Variations in the rate of synthesis of beta and beta'' RNA polymerase polypeptides under the influence of certain factors.

Summary In merodiploid cells containing a double dose of structural genes of RNA polymerase subunits-rpoBand rpoC-the rate of and subunits synthesis is 2 times higher than in haploidcells. Missence mutation rpoC1 (tsX) alters polypeptide and inducesthe and subunits synthesis at increased rate, particularly at a nonpermissive temperature. When rpoBCoperon carrying mutation rpoC1 is duplicated no dosage effect is observed. In the rpoC ⁺/rpoC1 heterodiploid the rpoC1 mutation does not significantly accelerate RNA polymerase subunits synthesis i.e. is recessive with respect to rpoC ⁺ Rifampicin causes 6-fold stimulation of RNA polymerase subunits synthesis in a sensitive wild-type strain. The rpoC1 mutation itself accelerates the synthesis of these subunits 3-fold. In the presence of rifampicin the mutant strain produces 13–22-fold faster as compared to wild-type strain without the drug. Thus, the effects of rifampicin and the mutation are multiplied suggesting that these factors act independently. Similar data have also been obtained with rifampicin-treated cells of rpoB22 (ts22) amber-mutant.After UV-irradiation of cells and synthesis is depressed much stronger than the total protein synthesis. Infection with a transducing phage rif ^d-47 which carries rpoB gene provokes a higher rate of synthesis. When pre-irradiated cells (500 erg/mm²) are infected with this phage, the rate of synthesis grows 20-fold compared to irradiated, non-infected cells and 6.5-fold compared to intact cells.The data are discussed in terms of the possible regulatory mechanisms of RNA polymerase subunit synthesis.