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.     

Histochemical observations on the taste buds of the marmosets (Callithrix jacchus and Callithrix penicillata).

The epithelial cells in the taste buds of C. jacchus and C. penicillata show a moderate amount of ribonucleic acid an a concentration of a PAS-positive diastase-resistant material at their apical part. These cells are devoid of UDPG-GT, phosphorylases, G-6-PA, alanyl aminopeptidase, leucine aminopeptidase, cholinesterase and MAO; they present a weak reaction of F-1, 6-P Ald, LDH, SDH, MDH, cytochrome oxidase, beta-OHBDH, nonspecific esterase and acid phosphatase and a stronger reaction to ADH, NADPH2-TR, ATPases, alpha-GPDH, alkaline phosphatase, 5-nucleotidase and GDH. Although some enzymes (alkaline phosphatase, 5-nucleotidase and ATPases) have an almost uniform reactivity by the several taste buds, the other ones react with a lesser intensity in the smaller uniform reactivity by the several taste buds, the other ones react with a lesser intensity in the smaller taste buds of the fungiform papillae. As a rule the apical part of the cells shows a stronger enzymatic reactivity. The taste buds of the marmosets are penetrated by acetylcholinesterase positive nerve fibers whereas the autonomic ganglia in the connective tissue contain both-acetyl and butyrylcholinesterase.     

NMR characterization of three forms of ferredoxin from Desulphovibrio gigas, a sulphate reducer

A NMR and magnetic susceptibility study of the oxidized and reduced states of three different oligomers (forms) of a [4Fe-4S] ferredoxin protein from Desulphovibrio gigas, FdI, FdI′, and FdII was carried out. FdI and FdI′ are different trimers and FdII a tetramer of the same basic subunit. A probable assignment of the contact shifted resonances is indicated. Since the temperature dependences of the contact shifted resonances associated with each [4Fe-4S] are not all similar a delocalized model for the spin densities on the 4Fe does not apply. The exchange rate between oxidized and reduced states is slow on the NMR time scale. The three oligomers are not magnetically equivalent. Using the “three state hypothesis” terminology it is shown that FdI_ox is predominantly in the C^2? state and changes upon reduction into the C^3? state, while FdII_ox is in the C^? state and changes into the C^2? state. FdI′ does not easily fit into this classification. This study shows a similarity of magnetic behaviour between FdI and bacterial ferredoxins (e.g. Bacillus polymyxa) and between FdII and HiPIP from Chromatium sp.. The influence of the quaternary structure on the stabilization of the different oxidation states of ferredoxins as well as on their redox potentials is discussed.     

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.     

M?ssbauer study of the native, reduced and substrate-reacted Desulfovibrio gigas aldehyde oxido-reductase.

The Desulfovibrio gigas aldehyde-oxido-reductase contains molybdenum and iron-sulfur clusters. M?ssbauer spectroscopy was used to characterize the iron-sulfur clusters. Spectra of the enzyme in its oxidized, partially reduced and benzaldehyde-reacted states were recorded at different temperatures and applied magnetic fields. All the iron atoms in D. gigas aldehyde oxido-reductase are organized as [2Fe-2S] clusters. In the oxidized enzyme, the clusters are diamagnetic and exhibit a single quadrupole doublet with parameters (delta EQ = 0.62 +/- 0.02 mm/s and delta = 0.27 +/- 0.01 mm/s) typical for the [2Fe-2S]2+ state. M?ssbauer spectra of the reduced clusters also show the characteristics of a [2Fe-2S]1+ cluster and can be explained by a spin-coupling model proposed for the [2Fe-2S] cluster where a high-spin ferrous ion (S = 2) is antiferromagnetically coupled to a high-spin ferric ion (S = 5/2) to form a S = 1/2 system. Two ferrous sites with different delta EQ values (3.42 mm/s and 2.93 mm/s at 85 K) are observed for the reduced enzyme, indicating the presence of two types of [2Fe-2S] clusters in the D. gigas enzyme. Taking this observation together with the re-evaluated value of iron content (3.5 +/- 0.1 Fe/molecule), it is concluded that, similar to other Mo-hydroxylases, the D. gigas aldehyde oxido-reductase also contains two spectroscopically distinguishable [2Fe-2S] clusters.     

The active centers of adenylylsulfate reductase from Desulfovibrio gigas. Characterization and spectroscopic studies

In order to utilize sulfate as the terminal electron acceptor, sulfate-reducing bacteria are equipped with a complex enzymatic system in which adenylylsulfate (AdoPSO4) reductase plays one of the major roles, reducing AdoPSO4 (the activated form of sulfate) to sulfite, with release of AMP. The enzyme has been purified to homogeneity from the anaerobic sulfate reducer Desulfovibrio gigas. The protein is composed of two non-identical subunits (70 kDa and 23 kDa) and is isolated in a multimeric form (approximately 400 kDa). It is an iron-sulfur, flavin-containing protein, with one FAD moiety, eight iron atoms and a minimum molecular mass of 93 kDa. Low-temperature EPR studies were performed to characterize its redox centers. In the native state, the enzyme showed an almost isotropic signal centered at g = 2.02 and only detectable below 20 K. This signal represented a minor species (0.10-0.25 spins/mol) and showed line broadening in the enzyme isolated from 57Fe-grown cells. Addition of sulfite had a minor effect on the EPR spectrum, but caused a major decrease in the visible region of the optical spectrum (around 392 nm). Further addition of AMP induced only a minor change in the visible spectrum whereas major changes were seen in the EPR spectrum; the appearance of a rhombic signal at g values 2.096, 1.940 and 1.890 (reduced Fe-S center I) observable below 30 K and a concomitant decrease in intensity of the g = 2.02 signal were detected. Effects of chemical reductants (ascorbate, H2/hydrogenase-reduced methyl viologen and dithionite) were also studied. A short time reduction with dithionite (15 s) or reduction with methyl viologen gave rise to the full reduction of center I (with slightly modified g values at 2.079, 1.939 and 1.897), and the complete disappearance of the g = 2.02 signal. Further reduction with dithionite produces a very complex EPR spectrum of a spin-spin-coupled nature (observable below 20 K), indicating the presence of at least two iron-sulfur centers, (centers I and II). M?ssbauer studies on 57Fe-enriched D. gigas AdoPSO4 reductase demonstrated unambiguously the presence of two 4Fe clusters. Center II has a redox potential less than or equal to 400 mV and exhibits spectroscopic properties that are characteristic of a ferredoxin-type [4Fe-4S] cluster. Center I exhibits spectra with atypical M?ssbauer parameters in its reduced state and has a midpoint potential around 0 mV, which is distinct from that of a ferredoxin-type [4Fe-4S] cluster, suggesting a different structure and/or a distinct cluster-ligand environment.