Microscopic anatomy of the ovary ofAlouatta caraya

The microscopic structure of theAlouatta caraya ovary is studied in different ages and reproductive stages. The most significant feature seems to be the presence in adult ovaries of abundant glandular interstitial tissue which occupies both the cortex and medulla. It seems to be derived from the theca interna of atretic follicles. Discrete luteinized masses are present in the medulla in all the ovaries observed. Invaginations of the surface epithelium are seen only in infant and juvenile ovaries. The development of cystic follicles seems to be a common pathway of atresia.     

Lordosis: Inhibiting effects of progesterone in the female rat

Progesterone has two types of inhibitory effects on female sexual behavior that have been well-documented in the guinea pig. The first occurs when high levels of progesterone are present around the start of the estrogen-priming process (“concurrent inhibition”). The second occurs immediately after the display of an estrogen-progesterone-induced period of estrous behavior (“sequential inhibition”). In the present set of experiments, we show that the rat, like the guinea pig, is capable of exhibiting both of these inhibitory effects of progesterone. However, rats require higher doses of progesterone than guinea pigs, at least for concurrent inhibition to be evident. In addition, we show that the dose of progesterone required in a single injection to produce concurrent inhibition is higher than the dose required to produce sequential inhibition in rats. A theory of how progesterone may be accomplishing its inhibitory effects on female sexual behavior in rodents is presented.     

Inducible α-glucosidase of Mucor rouxii: Effects of dimorphism on the development of the wall-bound activity

Some properties of the inducible α-glucosidase system of Mucor rouxii were investigated. This enzymatic activity was induced after resuspending glucose-grown cells in a maltose-supplemented medium. The wall-bound activity of α-glucosidase was determined by using intact cells in the enzymatic assay; this activity represented from 80 to 90% of the total activity present in the induced cells. The addition of glucose before, or during, the induction period repressed α-glucosidase synthesis. α-Glucosidase induction was tested under aerobic and anaerobic conditions. It was found that the enzyme synthesis and the appearance of wall-bound activity were not affected by changing the gaseous environment. On the other hand, it was observed that anaerobically grown yeast-like cells were much less efficient than aerobic mycelia to develop wall-bound α-glucosidase activity. This could explain earlier observations about the incapacity of M. rouxii to utilize maltose as a substrate for anaerobic growth. This idea was strengthened by the fact that, if an anaerobic culture was induced to develop under a mycelial morphology by adding to the medium the chemical agent EDTA, these cells also acquired the capacity to grow on maltose and concomitantly possessed wall-bound α-glucosidase activity. The relevance of the structure of the cell wall on the capacity of M. rouxii to metabolize maltose is discussed.     

An “Inclusion-Body-Like” Configuration of Some Cell Nuclei in Moose

At routine post-mortem of a moose an inclusion-body-like configuration of the nuclei of the cells in the granule layer of the cerebellum was found. This was also observed to a lesser extent in glial cells of the cerebrum, epithelial cells of the collecting tubules of kidney and in the hepatocytes.     

Nigericin forms highly stable complexes with lithium and cesium

Nigericin is a monocarboxylic polyether molecule described as a mobile K⁺ ionophore unable to transport Li⁺ and Cs⁺ across natural or artificial membranes. This paper shows that the ion carrier molecule forms complexes of equivalent energy demands with Li⁺, Cs⁺, Na⁺, Rb⁺, and K⁺. This is in accordance with the similar values of the complex stability constants obtained from nigericin with the five alkali metal cations assayed. On the other hand, nigericinalkali metal cation binding isotherms show faster rates for Li⁺ and Cs⁺ than for Na⁺, K⁺, and Rb⁺, in conditions where the carboxylic proton does not dissociate. Furthermore, proton NMR spectra of nigericin-Li⁺ and nigericin-Cs⁺ complexes show wide broadenings, suggesting strong cation interaction with the ionophore; in contrast, the complexes with Na⁺, K⁺, and Rb⁺ show only clear-cut chemical shifts. These latter results support the view that nigericin forms highly stable complexes with Li⁺ and Cs⁺ and contribute to the explanation for the inability of this ionophore to transport the former cations in conditions where it catalyzes a fast transport of K⁺>Rb⁺>Na⁺.Part of the results of this paper were presented at the 14th International Congress of Biochemistry in Prague, Czechoslovakia.     

3D structure of bovine pancreatic ribonuclease A in aqueous solution: An approach to tertiary structure determination from a small basis of1H NMR NOE correlations

Summary A method is proposed to generate initial structures in cases where the distance geometry method may fail, such as when the set of¹H NMR NOE-based distance constraints is small in relation to the size of the protein. The method introduces an initial correlation between the and backbone angles (based on empirical observations) which is relaxed in later stages of the calculation. The obtained initial structures are refined by well-established methods of energy minimization and restrained molecular dynamics. The method is applied to determine the solution structure of Ribonuclease A (124 residues) from a NOE basis consisting of 467 NOE cross-correlations (97 intra-residue, 206 sequential, 23 medium-range and 141 long-range) obtained at 360 MHz. The global shape and backbone overall fold of the eight final refined structures are close to those shown by the crystal structure. A meaningful difference in the positioning of the catalytically important His¹¹⁹ side chain in the solution and crystal structures has been detected.     

Permanent Stained Preparations of Synovial Fluid for Detection of Calcium Compounds Using Alizarin Red S

Permanent preparations of air dried synovial fluids were prepared by staining calcium compounds with alizarin red S stain; each slide was coverslipped with Permount. Variables studied were: (a) concentration of the solution of alizarin red S, (b) pH of staining solution, (c) time of incubation in staining solution and aqueous and ethanolic content of staining solution. The staining effect of each solution was tested on calcium pyrophosphate dihydrate, calcium oxalate, apatite and monosodium urate (MSU). Of all the solutions, best results were obtained with 0.25% alizarin red S in 50% ethanol at pH 7.0 for 30 min. With this solution, the calcium-containing compounds were well stained. MSU did not stain and still preserved negative birefringence on polarizaton. Fixation of smears with ethanol served a double purpose: It fixed the slides without dissolving or removing MSU or the calcium compounds, yet it did dissolve five corticosteroids commonly used for intra-articular injection which may interfere with interpretation of compensated polarized light microscopy of synovial fluids.     

Isolation and characterization of the Mg2(+)-ATPase from rabbit skeletal muscle sarcoplasmic reticulum membrane preparations

Preparations of sarcoplasmic reticulum vesicles, obtained according to the method of Eletr and Inesi (Biochim. Biophys. Acta (1972) 282, 174), contained both Mg2(+)-ATPase and Ca2+, Mg2(+)-ATPase activity. The two enzymes were solubilized by a mixture of digitonin and lysophosphatidylcholine and separated on a DEAE-cellulose column eluted with a discontinuous gradient of NaCl. The Mg2(+)-ATPase activity was eluted with 0.43 M NaCl. The Ca2+,Mg2(+)-ATPase was obtained by increasing the NaCl concentration of the elution medium to 0.40 M. The fraction eluted with 0.043 M NaCl was insensitive to micromolar concentrations of calcium, resistant to oligomycin, ouabain, orthovanadate and thiocyanate, and was inhibited by low concentrations of Triton X-100. The enzyme showed a single apparent Km for MgATP in the range of 0.2 mM and a Vm of 2.9 mumol Pi.min-1.mg-1 protein. Activity was maximal over a broad peak between pH 6.0-8.0. Hydrolysis of ATP was unaffected by dimethylsulfoxide concentrations up to 20% (v/v) and was inhibited at higher concentrations. The enzyme was not phosphorylated by either 32Pi or [gamma-32P]ATP at significant levels when compared with the Ca2+,Mg2(+)-ATPase in an EGTA-containing medium. The kinetic pattern of the Mg2(+)-ATPase was distinctly different from that of the Ca2+,Mg2(+)-ATPase under the same conditions. The fraction eluted from the DEAE-cellulose column was subjected to electrophoresis under non-denaturing conditions. Only one band with Mg2(+)-ATPase activity was detected. The Mg2(+)-ATPase migrated much slower than the Ca2+,Mg2(+)-ATPase under non-denaturing conditions, whereas both enzymes had a molecular mass of 105 kDa on SDS gel electrophoresis.     

Pregnancy termination by prostaglandin F2α stimulates maternal behavior in the rat

Treatment with PGF_2α resulted in the termination of pregnancy in 16- and 19-day pregnant rats, but not in 10- or 13-day pregnant rats. Rats that aborted displayed a rapid onset of maternal behavior when tested with foster pups. Aborted rats also displayed sexual receptivity and ovulation: these phenomena resemble the sequence of events following hysterectomy on the same days of pregnancy. Both can be related to the events surrounding normal parturition in the rat. The results are interpreted as due to a pregnancy-induced deactivation of the factor in the uterus that prevents estrogen from stimulating maternal behavior in nonpregnant females. In the absence of this factor, the PGF_2α-induced rise in estrogen secretion facilitates maternal behavior and sexual behavior and induces ovulation.     

Structural Characteristics of the Short-Tail Fibers of T4 Bacteriophage

The characteristics of pure preparations of short-tail fibers of bacteriophage T4 have been studied in the optical and electron microscope. Three main structures were observed: 1) spheres of 8.1 nm diameter; 2) fibers 43 nm long and 3.8 nm thick; and 3) fibers 54 nm long and 3.2 nm thick. Both types of fibers exhibited a regular beaded appearance. The 43-nm fibers were the most abundant structure. During the process of purification of the short-tail fibers, the formation of aggregates was observed each time the material containing the short-tail fibers was dialyzed against saline solutions. These aggregates became increasingly fibrous (as observed in the optical microscope) as the material used was increasingly enriched in short-tail fibers. Finally, most of the aggregates were of the fibrous type when they were formed from a purified preparation of short-tail fibers. In the electron microscope, it was found that the filamentous aggregates were organized in well-defined bundles. The amino acid composition of the highly purified short-tail fibers was also determined. Among the known fibrous proteins, the ones that most resemble the amino acid composition of the short-tail fibers are actin and fibrinogen. These observations are discussed in relation to the T4 short-tail fiber structure and their localization on the hexagonal baseplate of the T4 tail structure.