Effects of alpha-chlorohydrin on the male reproductive tissues of the Polynesian rat,Rattus exulans

Abstract

Doses of α-chlorohydrin (‘Epibloc’) were administered by gavage to mature male Polynesian rats (Rattus exulans) at 100, 200, and 300 mg per kg body weight. Animals that survived were sacrificed either 1 day or 7 days later for assessment of epididymal and testicular cytology and sperm viability. Two of 10 animals died 6 days after treatment with 100 mg/kg; 1/6 died within 24 h of treatment with 200 mg/kg, though 6/10 died when left for 7 days; 300 mg/kg was lethal to all 3 rats tested. After 1 day, microscopic lesions were observed in the Initial Segment of the epididymis of 4/6 rats dosed with 100 mg/kg and in all 5 of the 200 mg/kg group; however, in only one animal at the higher dose level was the damage severe enough to cause epithelial exfoliation and potential blockage of the lumen. In all the animals that survived for 7 days testicular and epididymal cytology were normal, and viable spermatozoa were present at all levels of the tract. Autopsies revealed no evidence of gross epididymal lesions in any of the animals that died from the drug. We conclude that although α-chlorohydrin causes minor lesions in the epididymis of this feral species, the damage appears to be reversible in animals that survive an acute dose, and the drug cannot be considered an effective chemosterilant, as distinct from a poison.     

Detection of Genes with Atypical Nucleotide Sequence in Microbial Genomes

Along the gene, nucleotides in various codon positions tend to exert a slight but observable influence on the nucleotide choice at neighboring positions. Such context biases are different in different organisms and can be used as genomic signatures. In this paper, we will focus specifically on the dinucleotide composed of a third codon position nucleotide and its succeeding first position nucleotide. Using the 16 possible dinucleotide combinations, we calculate how well individual genes conform to the observed mean dinucleotide frequencies of an entire genome, forming a distance measure for each gene. It is found that genes from different genomes can be separated with a high degree of accuracy, according to these distance values. In particular, we address the problem of recent horizontal gene transfer, and how imported genes may be evaluated by their poor assimilation to the host's context biases. By concentrating on the third- and succeeding first position nucleotides, we eliminate most spurious contributions from codon usage and amino-acid requirements, focusing mainly on mutational effects. Since imported genes are expected to converge only gradually to genomic signatures, it is possible to question whether a gene present in only one of two closely related organisms has been imported into one organism or deleted in the other. Striking correlations between the proposed distance measure and poor homology are observed when Escherichia coli genes are compared to Salmonella typhi, indicating that sets of outlier genes in E. coli may contain a high number of genes that have been imported into E. coli, and not deleted in S. typhi. Received: 16 January 2001 / Accepted: 30 August 2001     

An Approach to Prebiotic Synthesis of α-Oligoribonucleotides and Description of Their Properties: Selective Advantage of β-RNA over α-RNA

Oligomerization of α-adenosine 5′-phosphorimidazolide (α-ImpA) has been done in an aqueous solution using a uranyl-ion catalyst or a poly(U) template as a model process of prebiotic synthesis of RNA with α-glycosidic linkage. α-Oligoriboadenylates up to hexamer were formed from α-ImpA by the uranyl-ion catalyst. 3′-5′ Linkage was mainly formed in the oligomerization. The poly(U) template mediated the oligomerization of α-ImpA, but to a very low extent. The yield and chain length of the resulting α-oligomers were far lower than those of the corresponding β-oligomer formation under the same conditions. Physico-chemical properties of α-oligoriboadenylates are presented along with those of the corresponding β-oligoriboadenylates. The results indicate that β-RNA is more advantageous than α-RNA from the points of their synthesis and properties. Received: 10 February 1997 / Accepted: 31 March 1997     

Identification of Sequences Encoding the Detoxification Metalloisomerase Glyoxalase I in Microbial Genomes from Several Pathogenic Organisms

The ubiquitous glyoxalase system, which is composed of two enzymes, removes cellular cytotoxic methylglyoxal (MG). In an effort to identify critical residues conserved in the evolution of the first enzyme in this system, glyoxalase I (GlxI), as well as the structural implications of sequence alterations in this enzyme, a search of the National Center for Biotechnology Information (NCBI) database of unfinished genomes was undertaken. Eleven putative GlxI sequences from pathogenic organisms were identified and analyses of these sequences in relation to the known and previously identified GlxI enzymes were performed. Several of these sequences show a very high similarity to the Escherichia coli GlxI sequence, most notably the 79% identity of the sequence identified from Yersinia pestis, the causative agent of bubonic plague. In addition to the conservation of residues critical to binding the catalytic metal in all of the proposed GlxI enzymes, four regions in the Homo sapiens GlxI enzyme are absent in all of the bacterial GlxI sequences, with the exception of Pseudomonas putida. Removal of these regions may alter the active-site conformation of the bacterial enzymes in relation to that of the H. sapiens. These differences may be targeted for the development of inhibitors selective to the bacterial enzymes. Received: 13 October 1999 / Accepted: 17 January 2000     

Microbial Relatives of Seed Storage Proteins: Conservation of Motifs in a Functionally Diverse Superfamily of Enzymes

Plant storage proteins comprise a major part of the human diet. Sequence analysis has revealed that these proteins probably share a common ancestor with a fungal oxalate decarboxylase and/or related bacterial genes. Additionally, all these proteins share a central core sequence with several other functionally diverse enzymes and binding proteins, many of which are associated with synthesis of the extracellular matrix during sporulation/encystment. A possible prokaryotic relative of this sequence is a bacterial protein (SASP) known to bind to DNA and thereby protect spores from extreme environmental conditions. This ability to maintain cell viability during periods of dehydration in spores and seeds may relate to absolute conservation of residues involved in structure determination. Received: 25 April 1997 / Accepted: 29 July 1997     

What Is Characteristic of Fungal Lysine Synthesis Through the α-Aminoadipate Pathway?

Recent finding that a prokaryote synthesizes lysine through the α-aminoadipate pathway demonstrates that the lysine synthesis through the α-aminoadipate pathway is not typical of fungi. However, the fungal lysine biosynthesis is not completely the same as the prokaryotic one. We point out that α-aminoadipate reductase is a key enzyme to the evolution of fungal lysine synthesis. In addition, fungi have two different saccharopine dehydrogenases, which is also characteristic of fungi. Received: 18 February 2000 / Accepted: 19 June 2000     

Microbial reduction of metals and radionuclides

The microbial reduction of metals has attracted recent interest as these transformations can play crucial roles in the cycling of both inorganic and organic species in a range of environments and, if harnessed, may offer the basis for a wide range of innovative biotechnological processes. Under certain conditions, however, microbial metal reduction can also mobilise toxic metals with potentially calamitous effects on human health. This review focuses on recent research on the reduction of a wide range of metals including Fe(III), Mn(IV) and other more toxic metals such as Cr(VI), Hg(II), Co(III), Pd(II), Au(III), Ag(I), Mo(VI) and V(V). The reduction of metalloids including As(V) and Se(VI) and radionuclides including U(VI), Np(V) and Tc(VII) is also reviewed. Rapid advances over the last decade have resulted in a detailed understanding of some of these transformations at a molecular level. Where known, the mechanisms of metal reduction are discussed, alongside the environmental impact of such transformations and possible biotechnological applications that could utilise these activities.     

Stereospecific synthesis of α-methylated amino acids

Summary. Both 2,5-trans and 2,5-cis disubstituted 2-tert-butyl-5-(indol-3-yl)methylimidazolidin-4-ones were synthesised and their enolates were prepared using LDA. While the enolate of the 2,5-trans disubstituted derivative could not be methylated, the enolate of the cis-2,5-disubstituted derivative was successfully methylated with methyl iodide to a product which on hydrolysis gave enantiomerically pure α-methyl-L-tryptophan. Received October 31, 1998, Accepted July 23, 1999     

Microbial models of soil metabolism: biotransformations of danofloxacin

Danofloxacin is a new synthetic fluoroquinolone antibacterial agent under development for exclusive use in veterinary medicine. Such use could lead to deposition of low levels of danofloxacin residues in the environment in manure from treated livestock. This study was conducted to evaluate the potential for indigenous soil microorganisms to metabolize danofloxacin. Cultures of 72 soil microorganisms representing a diverse panel of bacteria, fungi and yeast were incubated with danofloxacin mesylate substrate and samples analyzed periodically by high performance liquid chromatography for loss of danofloxacin and formation of metabolites. Some samples were further analyzed by liquid chromatography-mass spectrometry and mass spectrometry to confirm metabolite identification. Twelve organisms, representing eight different genera, biotransformed danofloxacin to metabolites detectable by the chromatographic methods employed. Two Mycobacterium species, two Pseudomonas species, and isolates of Nocardia sp, Rhizopus arrhizus and Streptomyces griseus all formed N-desmethyldanofloxacin. The formation of the 7-amino danofloxacin derivative, 1-cyclopropyl-6-fluoro-7-amino-4-oxo-1,4-dihydroquinoline-3-carboxylic acid by cultures of Candida lipopytica, Pseudomonas fluorescens, two Mycobacterium species and three Penicillium species demonstrates the propensities of these cultures to completely degrade the piperazine ring. At least two additional and unidentified metabolite peaks were observed in chromatograms of Aspergillus nidulans and Penicillium sp cultures. Radiolabled [2-¹⁴C]danofloxacin added to cultures of the fungus Curvularia lunata was apparently mineralized, with approximately 31% of the radiolabel recovered as volatile metabolites after 24 h of incubation, indicating the susceptibility of the quinolone ring to microbial metabolic degradation. Received 09 December 1996/ Accepted in revised form 09 April 1997     

Thermophilic Microbial Metal Reduction

Thermophilic microorganisms can reduce Fe(III), Mn(IV), Cr(VI), U(VI), Tc(VII), Co(III), Mo(VI), Au(I, III), and Hg(II). Ferric iron and Mn(IV) can be used as electron acceptors during growth; the physiological role of the reduction of the other metals is unclear. The process of microbial dissimilatory reduction of Fe(III) is the most thoroughly studied. Iron-reducing prokaryotes have been found in virtually all of the recognized types of terrestrial ecosystems, from hot continental springs to geothermally heated subsurface sediments. Thermophilic iron reducers do not belong to a phylogenetically homogenous group and include representatives of many bacterial and archaeal taxa. Iron reducing thermophiles can couple Fe(III) reduction with oxidation of a wide spectrum of organic and inorganic compounds. In the thermophilic microbial community, they can fulfil both degradative and productive functions. Thermophilic prokaryotes probably carried out global reduction of metals on Earth in ancient times, and, at the same time, they are promising candidates for use in modern biotechnological processes.     

Consequences of renal mass reduction on amino acid and biogenic amine levels in nephrectomized mice

Summary. Amino acid and biogenic amine changes were investigated in nephrectomized mice ten days postsurgery. Uremic mice exhibited changes in amino acid concentrations in plasma, urine and brain. Particularly plasma methionine, citrulline and arginine levels were significantly enhanced in nephrectomized mice compared to controls whereas serine was decreased. Urinary excretion of methionine, citrulline and alanine was higher in nephrectomized mice compared to controls whereas many amino acids were increased in brain of nephrectomized mice. Brain and urinary amino acid changes were more pronounced in the 75% than in the 50% nephrectomized mice. Brain norepinephrine and dopamine and its metabolites 3,4-dihydroxyphenylacetic acid and homovanillic acid were significantly increased whereas serotonin was decreased comparing the 75% nephrectomized mice to the sham-operated mice. This study demonstrates that at very early stages of renal insufficiency, specific amino acid and biogenic amine changes occur in plasma, urine and brain. These alterations might depend qualitatively and quantitatively on the degree of functional renal mass reduction. Received April 5, 1999     

Microbial diversity: the importance of exploration and conservation

Microbial diversity is fundamental to maintenance and conservation of global genetic resources. As extreme environments are explored, the richness of microbial diversity is increasingly evident. Measures must be taken to estimate, record, and conserve microbial diversity, not only to sustain human health but also to enrich the human condition globally through wise use and conservation of genetic resources of the microbial world. Received 24 April 1996/ Accepted in revised form 07 January 1997     

Review: Microbial synthesis of agrochemical metabolites

The synthesis of agrochemical metabolite reference standards by microbial cultures can serve as a useful alternative to conventional chemical synthesis, particularly when the chemical synthesis is difficult. Microbially generated metabolites of agrochemicals can also be useful for predicting degradative pathways in animals, plants and soils prior to conducting animal, plant and soil metabolism studies which are required by regulatory agencies to support agrochemical registrations. Examples from the literature are used to illustrate the utility of synthesizing metabolites of agrochemicals by common microbes. Received 17 January 1997/ Accepted in revised form 20 March 1997     

Synthesis of new α-heterocyclic α-aminoesters

alpha-Heterocyclic alpha-aminoesters were obtained in good yields by reaction of a glycine cation equivalent and different heterocyclic nucleophiles; diastereoselectivity using a carbohydrate (galactopyranose) as N-protecting group was modest.     

Enhancement of transglutaminase activity and polyamine depletion in B16-F10 melanoma cells by flavonoids naringenin and hesperitin correlate to reduction of the <Emphasis Type="Italic">in vivo</Emphasis> metastatic potential

Summary. The in vitro and in vivo effects of two flavonons, naringenin (NG) and hesperitin (HP) on the proliferation rate of highly metastatic murine B16-F10 melanoma cell were investigated. NG or HP treatment of melanoma cells produced a remarkable reduction of cell proliferation, paralleled with both the lowering of the intracellular levels of polyamine, spermidine and spermine and the enhancement of transglutaminase (TGase, EC 2.3.2.13) activity. Orally administered NG or HP in C57BL6/N mice inoculated with B16-F10 cells affected the pulmonary invasion of melanoma cells in an in vivo metastatic assay. The number of lung metastases detected by a computerized image analyzer was reduced, compared to untreated animals, by about 69% in NG-treated mice and by about 36% in HP-treated mice. Survival studies showed that 50% of the NG-treated animals died 38 ± 3.1 days after tumor cell injection (control group: 18 ± 1.5 days) and HP-treated mice died 27 ± 2.3 days after cell inoculation. Taken together, these findings provide further evidences for the potential anticancer properties of dietary flavonoids as chemopreventive agents against malignant melanoma.     

Ferric reduction by iron-limited Chlamydomonas cells interacts with both photosynthesis and respiration

Iron limitation led to a large increase in extracellular ferricyanide (Fe[III]) reductase activity in cells of the green alga Chlamydomonas reinhardtii Dangeard. Mass-spectrometric measurement of gas exchange indicated that ferricyanide reduction in the dark resulted in a stimulation of respiratory CO₂ production without affecting the rate of respiratory O₂ consumption, consistent with the previously postulated activation of the oxidative pentose phosphate pathway in support of Fe(III) reduction by iron-limited Chlamydomonas cells (X. Xue et al., 1998, J. Phycol. 34: 939–944). At saturating irradiance, the rate of ferricyanide reduction was stimulated almost 3-fold, and this stimulation was inhibited by 3-(3′,4′-dichlorophenyl)-1,1-dimethylurea. Ferricyanide reduction during photosynthesis resulted in approximately a 50% inhibition of photosynthetic CO₂ fixation at saturating irradiance, and almost 100% inhibition of CO₂ fixation at sub-saturating irradiance. Photosynthesis by iron-sufficient cells was not affected by ferricyanide addition. Addition of 250 μM ferricyanide to iron-limited cells in which photosynthesis was inhibited (either by the presence of glycolaldehyde, or by maintaining the cells at the CO₂ compensation point) resulted in a stimulation in the rate of gross photosynthetic O₂ evolution. Chlorophyll a fluorescence measurements indicated a large increase in non-photochemical quenching during ferricyanide reduction in the light; the increase in nonphotochemical quenching was abolished by the addition of nigericin. These results suggest that reduction of extracellular ferricyanide (mediated at the plasma membrane) interacts with both photosynthesis and respiration, and that both of these processes contribute NADPH in the light. Received: 15 September 1999 / Accepted: 14 October 1999     

Isolation and characterization; of α-santonin assimilating pseudomonad

Pseudomonas cichorii strainS, isolated by soil enrichment technique, utilized santonin as the sole source of carbon, forming chromatographically destinguishable transformation products. One of the intermediary transformation products was identified as 1,2-dihydro α-santonin.     

Phylogenetic Relationships Among Hypotrichous Ciliates Determined with the Macronuclear Gene Encoding the Large, Catalytic Subunit of DNA Polymerase α

The complete macronuclear DNA polymerase α gene, previously sequenced in Oxytricha nova, has been cloned from a genomic macronuclear library and sequenced for the hypotrich O. trifallax. Macronuclear DNA clones of DNA polymerase α encoding ∼1000 amino acids, or approximately two-thirds of the open reading frame, have been obtained by PCR and sequenced for Halteria grandinella, Holosticha species, Paraurostyla viridis, Pleurotricha lanceolata, Stylonychia lemnae Teller, Sty. mytilus, Uroleptus gallina, and Urostyla grandis. Phylogenetic relationships inferred from DNA polymerase α amino acid sequences have been used to clarify taxonomic relationships previously determined by morphology of the cell cortex. Hypotrich phylogenies based on DNA polymerase α amino acid sequences are incongruent with morphological and other molecular phylogenies. Based upon these data, we assert that, contrary to morphological data, O. nova and O. trifallax are different species, and we propose that the oligotrich Halteria grandinella be reclassified as a hypotrich. This work also extends the available data base of eukaryotic DNA polymerase α sequences, and suggests new amino acid sequence targets for mutagenesis experiments to continue the functional dissection of DNA pol α biochemistry at the molecular level. Received: 7 January 1997 / Accepted: 7 April 1997