The biosynthesis of hydroxynalidixic acid.

Analytical methods have been worked out for the study of the human metabolism of nalidixic acid. Under pathological conditions the excretion of its metabolites differed from that observed in healthy volunteers. The cause of these variations was studied on the basis of individual excretion curves. The results showed that human and microbial biotransformations were identical. The possibilites offered by the new methods in drug research are discussed.     

Sequence of a cDNA for mouse thymidylate synthase reveals striking similarity with the prokaryotic enzyme

We report the nucleotide sequence of a cloned cDNA, pMTS-3, that contains a 1-kb insert corresponding to mouse thymidylate synthase (E.C. 2.1.1.45). The open reading frame of 921 nucleotides from the first AUG to the termination codon specifies a protein with a molecular mass of 34,962 daltons. The predicted amino acid sequence is 90% identical with that of the human enzyme. The mouse sequence also has an extremely high degree of similarity (as much as 55% identity) with prokaryotic thymidylate synthase sequences, indicating that thymidylate synthase is among the most highly conserved proteins studied to date. The similarity is especially pronounced (as much as 80% identity) in the 44-amino-acid region encompassing the binding site for deoxyuridylic acid. The cDNA sequence also suggests that mouse thymidylate synthase mRNA lacks a 3' untranslated region, since the termination codon, UAA, is followed immediately by a poly(A) segment.      

Action competitive d'helisoma duryi,wetherby (Planorbidae : Helisomatinae) a l'egard de divers mollusques vecteurs de trematodoses humaines et animales. I. Biomphalaria glabrata,say

Laboratory experiments indicate that Helisoma duryi may be a promising biological control agent of human Schistosomiasis by acting as a predator of very young Biomphalaria glabrata and, when the two planorbid snails are maintained together, in influencing infection rate of Biomphalaria by miracidia of Schistosoma mansoni and their cercarial production.(avec la collaboration technique de R. THOMASSET)     

A double role of sperm in scorpions: The mating plug of Euscorpius italicus (Scorpiones: Euscorpiidae) consists of sperm

Mating plugs occluding the female gonopore after mating are a widespread phenomenon. In scorpions, two main types of mating plugs are found: sclerotized mating plugs being parts of the spermatophore that break off during mating, and gel‐like mating plugs being gelatinous fluids that harden in the female genital tract. In this study, the gel‐like mating plug of Euscorpius italicus was investigated with respect to its composition, fine structure, and changes over time. Sperm forms the major component of the mating plug, a phenomenon previously unknown in arachnids. Three parts of the mating plug can be distinguished. The part facing the outside of the female (outer part) contains sperm packages containing inactive spermatozoa. In this state, sperm is transferred. In the median part, the sperm packages get uncoiled to single spermatozoa. In the inner part, free sperm is embedded in a large amount of secretions. Fresh mating plugs are soft gelatinous, later they harden from outside toward inside. This process is completed after 3‐5 days. Sperm from artificially triggered spermatophores could be activated by immersion in insect Ringer's solution indicating that the fluid condition in the females' genital tract or females' secretions causes sperm activation. Because of the male origin of the mating plug, it has likely evolved under sperm competition or sexual conflict. As females refused to remate irrespective of the presence or absence of a mating plug, females may have changed their mating behavior in the course of evolution from polyandry to monandry. J. Morphol., 2010. © 2010 Wiley‐Liss, Inc.     

Mandibular growth in the rhesus monkey (Macaca mulatta)

Mandibular growth of 42 rhesus monkeys (Macaca mulatta) was analyzed quantitatively and qualitatively. Four groups of animals were defined according to dentitional age (i.e., infant, juvenile, adolescent, young adult). At each age growth was observed for a 24 week period. Since some animals were observed at more than one stage of development, 57 periods of growth were studied. The growth incremental data were collected by superimposing serial cephalograms on mandibular implants. Growth and remodeling of both the skeletal and dento-alveolar components of the rhesus mandible were greatest in the infant monkeys and were less in successive age groups. Posterior relocation of the ramus was noted in all age groups while bone deposition on the anterior and inferior borders of the mandibular body was greatest in the younger animals. The most pronounced dental changes also occurred in the younger animals while the dentitions of the adolescent and adult animals were generally more stable. This study demonstrates that the rate and direction of normal mandibular growth varies with the age of the animal. Furthermore, mandibular growth is quantified at four defined maturational levels to provide a set of values illustrating normal mandibular growth. These values can also be used as control data for experimental studies.     

Drowning-out crystallisation of sodium sulphate using aqueous two-phase systems

A novel method to obtain crystals of pure, anhydrous salt, using aqueous two-phase systems was studied. A concentrated salt solution is mixed with polyethylene glycol (PEG), upon which three phases are formed: salt crystals, a PEG-rich liquid and a salt-rich liquid. After removal of the solid salt, a two-phase system is obtained. Both liquid phases are recycled, allowing the design of a continuous process, which could be exploited industrially. The phase diagram of the system water–Na₂SO₄–PEG 3350 at 28°C was used. Several process alternatives are proposed and their economic potential is discussed. The process steps needed to produce sodium sulphate crystals include mixing, crystallisation, settling and, optionally, evaporation of water. The yield of sodium sulphate increases dramatically if an evaporation step is used.     

Electrogenic Na-independent HCO3 transport in OK cells.

We have shown previously that OK cells recover from an acid load in a medium nominally CO2-free by extruding H via a Na/H exchanger and a passive H-conductive pathway. In this work, the regulation of cell pH (pHi) was studied after addition or withdrawal of CO2/HCO3 (5% CO2, 95 mM HCO3, pH = 8) using the fluoroprobe BCECF. In the presence of Na and amiloride to inhibit Na/H exchange, the recovery of pHi after CO2 entry and CO2 exit were found to depend in part on HCO3 entry and exit, respectively. Efflux of H per se also contributed to restoring pHi after CO2 addition, whereas H influx may have played a smaller role to normalize pHi after CO2 removal. DIDS, 0.5 mM, significantly inhibited both recovery phases of pHi. Removal of Na failed to inhibit the recovery of pHi after CO2 addition and removal. Cl removal also failed to inhibit pHi recovery after CO2 removal. Cell depolarization in the presence of Na moderately stimulated the pHi recovery rate after CO2 addition whereas it markedly inhibited the normalization of pHi after CO2 removal. Cell depolarization in the absence of sodium had only a slight effect to increase pHi recovery after CO2 addition but markedly prevented the pHi recovery after CO2 removal. These results indicate that OK cells lack Na or Cl-dependent HCO3 transport systems. The OK cell possesses a novel stilbene-sensitive electrogenic HCO3 transport system that is involved in the regulation of cell pH.