Trial of Lixisenatide in Early Parkinson's Disease

BACKGROUND

Lixisenatide, a glucagon-like peptide-1 receptor agonist used for the treatment of diabetes, has shown neuroprotective properties in a mouse model of Parkinson's disease.

METHODS

In this phase 2, double-blind, randomized, placebo-controlled trial, we assessed the effect of lixisenatide on the progression of motor disability in persons with Parkinson's disease. Participants in whom Parkinson's disease was diagnosed less than 3 years earlier, who were receiving a stable dose of medications to treat symptoms, and who did not have motor complications were randomly assigned in a 1:1 ratio to daily subcutaneous lixisenatide or placebo for 12 months, followed by a 2-month washout period. The primary end point was the change from baseline in scores on the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part III (range, 0 to 132, with higher scores indicating greater motor disability), which was assessed in patients in the on-medication state at 12 months. Secondary end points included other MDS-UPDRS subscores at 6, 12, and 14 months and doses of levodopa equivalent.

RESULTS

A total of 156 persons were enrolled, with 78 assigned to each group. MDS-UPDRS part III scores at baseline were approximately 15 in both groups. At 12 months, scores on the MDS-UPDRS part III had changed by -0.04 points (indicating improvement) in the lixisenatide group and 3.04 points (indicating worsening disability) in the placebo group (difference, 3.08; 95% confidence interval, 0.86 to 5.30; P = 0.007). At 14 months, after a 2-month washout period, the mean MDS-UPDRS motor scores in the off-medication state were 17.7 (95% CI, 15.7 to 19.7) with lixisenatide and 20.6 (95% CI, 18.5 to 22.8) with placebo. Other results relative to the secondary end points did not differ substantially between the groups. Nausea occurred in 46% of participants receiving lixisenatide, and vomiting occurred in 13%.

CONCLUSIONS

In participants with early Parkinson's disease, lixisenatide therapy resulted in less progression of motor disability than placebo at 12 months in a phase 2 trial but was associated with gastrointestinal side effects. Longer and larger trials are needed to determine the effects and safety of lixisenatide in persons with Parkinson's disease. (Funded by the French Ministry of Health and others; LIXIPARK ClinicalTrials.gov number, NCT03439943.).

A Double-Blind, Randomized, Placebo-Controlled Trial of Bumetanide in Parkinson's Disease

BACKGROUND

Acting on the main target of dopaminergic cells, the striatal γ-aminobutyric acid (GABA)-ergic cells, might be a new way to treat persons with Parkinson's disease (PD).

OBJECTIVE

The objective of this study was to assess the efficacy of bumetanide, an Na-K-Cl cotransporter (NKCC1) inhibitor, to improve motor symptoms in PD.

METHODS

This was a 4-month double-blind, randomized, parallel-group, placebo-controlled trial of 1.75 to 3 mg/day bumetanide as an adjunct to levodopa in 44 participants with PD and motor fluctuations.

RESULTS

Compared to the baseline, the mean change in OFF Movement Disorder Society Unified Parkinson's Disease Rating Scale Part III score after 4 months of treatment (primary endpoint) did not improve significantly compared with placebo. No changes between participants treated with bumetanide and those treated with placebo were observed for most other outcome measures. Despite no relevant safety signals, bumetanide was poorly tolerated.

CONCLUSIONS

There was no evidence in this study that bumetanide has efficacy in improving motor symptoms of PD. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Using middle finger length to determine the internal diameter of uncuffed tracheal tubes in paediatrics

The selection of an appropriately-sized tracheal tube is of critical importance in paediatric patients to reduce both the risk of subglottic stenosis from a tracheal tube that is too large, and inadequate ventilation or poor end-tidal gas monitoring from a tracheal tube that is too small. Age formulae are widely used, but known to be unreliable, often resulting in a need to change the tracheal tube. Previous work has shown that the length of the middle finger and the internal diameter can both be used to guide depth of tracheal tube insertion. Therefore, we hypothesised that middle finger length may also be related to tube internal diameter. We enrolled children aged up to 12 years presenting to our institution for elective anaesthesia and measured the length of the middle finger on the palmar aspect of the hand. Anaesthetists chose the airway device they felt most appropriate for the procedure, and were unaware of the middle finger measurement. Of 160 patients who were enrolled, 108 were included in the final analysis. We found a linear relationship between uncuffed tracheal tube internal diameter and median middle finger length for each size of tracheal tube. Relationship between middle finger length and cuffed tracheal tube internal diameter was less clear. We propose that the formula: 'middle finger length (cm) (round up to nearest 0.5) = internal diameter of uncuffed tracheal tube (mm)' may be an improvement compared with age formulae for selecting uncuffed tracheal tubes in children, although this requires formal testing.

Molecular detection of human rhinoviruses in respiratory samples: a comparison of Taqman probe-, SYBR green I- and BOXTO-based real-time PCR assays

BACKGROUND

Human Rhinoviruses (HRV) are major causative agents of acute respiratory tract infections in all age group and important contributing factors of childhood morbidity and mortality. Clinical presentation is poorly specific and the great antigenic and genetic variability of HRVs renders the biological diagnosis complex. Here, we have evaluated several molecular diagnostic protocols, including Taqman probe-based and intercalating agent-based RT-PCR assays.

METHODS

5,627 respiratory samples sent to the laboratory of Virology of the University Hospitals of Marseille, France, from March 2011 to February 2012, were tested using a real-time RT-PCR assay in the 5'NCR of the rhinoviral genome that associated a Taqman probe and the detection of DNA-BOXTO-dye complexes. A sample of 500 BOXTO-positive samples were further tested using the same probe assay (without BOXTO), and a SYBR Green assay (using the same amplification primers). The specific amplification of HRV sequences was assessed by NGS amplicon sequencing.

RESULTS

The Taqman probe RT-PCR assay identified 696/5,627 samples (12,4%) as HRV-positive. BOXTO-positive samples included all probe-positive samples and 1,913 additional samples, of which only 24.3% were confirmed by sequencing. The SYBR Green assay was more specific (16/550 samples were probe-negative/SYBR Green-positive, all confirmed by 5'NCR sequencing), but 3/500 samples were probe-positive/SYBR Green-negative.

CONCLUSIONS

Our results highlight the difficulty in detecting HRVs in clinical samples using a single molecular detection system. Amongst the 3 systems tested, the best compromise was obtained with the SYBR Green assay, which, by comparison with our probe-based assay provided an improved sensitivity without altering the detection specificity. Interestingly, a majority of probe-negative/BOXTO- or SYBR Green-positive samples were not associated with mutations in the sequence targeted by the probe. Sequence-based modifications of the secondary structure of the HRV 5'NCR may be associated with a limited access to the probe hybridisation region. Further investigations may identify a test combining a probe based- and an intercalating agent-based detection, which will significantly improve the diagnosis of HRV infections.

Comparative evaluation of the toxicity and genotoxicity of cadmium in amphibian larvae (Xenopus laevis and Pleurodeles waltl) using the comet assay and the micronucleus test

The toxic and genotoxic potential of Cadmium (CdCl(2)) were evaluated by the micronucleus test (MNT) and comet assay (CA) using amphibian larvae (Xenopus laevis and Pleurodeles waltl). Acute toxicity results showed that Cd is toxic to Xenopus larvae exposed from 2 to 50 mg/L and to Pleurodeles from 5 to 50 mg/L, depending on the nature of the water (reconstituted water containing mineral salts or mineral water MW (Volvic)). The MNT results obtained in MW showed that Cd (2 mg/L) is genotoxic to Xenopus, whereas it was not genotoxic to Pleurodeles at all concentrations tested. The CA established that the genotoxicity of Cd to Xenopus and Pleurodeles larvae depends on the concentration, the exposure times, and the comet parameters (Tail DNA, ETM, OTM, and TL). The CA and MNT results were compared for their ability to detect genotoxic effects, considering the concentrations of Cd applied and the exposure time. The CA showed Cd to be genotoxic from the first day of exposure. In amphibians, the CA appears to be a sensitive and suitable method for detecting genotoxicity such as that caused by Cd.

Comparative evaluation of genotoxicity of captan in amphibian larvae (Xenopus laevis and Pleurodeles waltl) using the comet assay and the micronucleus test

Captan (N-trichloromethylthio-4-cyclohexene-1,2-dicarboximide) is a fungicide used to inhibit the growth of many types of fungi on plants used as foodstuffs. The toxic and genotoxic potentials of captan were evaluated with the micronucleus test (MNT; AFNOR,2000) and the comet assay (CA) using amphibian larvae (Xenopus laevis and Pleurodeles waltl). Acute toxicity results showed that captan was toxic (1) to Xenopus larvae exposed to from 2 mg/L to 125 or 62.5 microg/L, depending on the nature of the water [reconstituted water containing mineral salts or mineral water (MW; Volvic, Danone, France)] and (2) to Pleurodeles exposed to from 2 mg/L to 125 microg/L in both types of water. The MNT results obtained in MW showed that captan (62.5 microg/L) was genotoxic to Xenopus but not genotoxic to Pleurodeles at all concentrations tested. CA established that the genotoxicity of captan to Xenopus and Pleurodeles larvae depended on the concentration, the exposure times, and the comet parameters (tail DNA, TEM, OTM, and TL). The CA and MNT results were compared for their ability to detect DNA damage at the concentrations of captan and the exposure times applied. CA showed captan to be genotoxic from the first day of exposure. In amphibians, CA appears to be a sensitive and suitable method for detecting genotoxicity such as that caused by captan.

Biomonitoring of the genotoxic potential of aqueous extracts of soils and bottom ash resulting from municipal solid waste incineration, using the comet and micronucleus tests on amphibian (Xenopus laevis) larvae and bacterial assays (Mutatox and Ames tests)

The management of contaminated soils and wastes is a matter of considerable human concern. The present study evaluates the genotoxic potential of aqueous extracts of two soils (leachates) and of bottom ash resulting from municipal solid waste incineration (MSWIBA percolate), using amphibian larvae (Xenopus laevis). Soil A was contaminated by residues of solvents and metals and Soil B by polycyclic aromatic hydrocarbons and metals. MSWIBA was predominantly contaminated by metals. Two genotoxic endpoints were analysed in circulating erythrocytes taken from larvae: clastogenic and/or aneugenic effects (micronucleus induction) after 12 days of exposure and DNA-strand-breaking potency (comet assay) after 1 and 12 days of exposure. In addition, in vitro bacterial assays (Mutatox and Ames tests) were carried out and the results were compared with those of the amphibian test. Physicochemical analyses were also taken into account. Results obtained with the amphibians established the genotoxicity of the aqueous extracts and the comet assay revealed that they were genotoxic from the first day of exposure. The latter test could thus be considered as a genotoxicity-screening tool. Although genotoxicity persisted after 12 days' exposure, DNA damage decreased overall between days 1 and 12 in the MSWIBA percolate, in contrast to the soil leachates. Bacterial tests detected genotoxicity only for the leachate of soil A (Mutatox). The results confirm the ecotoxicological relevance of the amphibian model and underscore the importance of bioassays, as a complement to physico-chemical data, for risk evaluation.

Biomonitoring of the genotoxic potential of draining water from dredged sediments, using the comet and micronucleus tests on amphibian (Xenopus laevis) larvae and bacterial assays (Mutatox and Ames tests)

Management of contaminated dredged sediments is a matter of great human concern. The present investigation evaluates the genotoxic potential of aqueous extracts of five sediments from French channels (draining water from dredged sediments), using larvae of the frog Xenopus laevis. Two genotoxic endpoints were analyzed in larvae: clastogenic and/or aneugenic effects (micronucleus induction after 12 d of exposure) and DNA-strand breaking potency (comet assay after 1 and 12 d of exposure) in the circulating blood. Additionally, in vitro bacterial assays (Microtox and Ames tests) were carried out and the results were compared with those obtained with larvae. Physicochemical analyses were also taken into account. Analytical analyses highlighted in the five draining waters a heavy load of contaminants such as metals and hydrocarbons. The results obtained with the micronucleus test established the genotoxicity of three draining waters. The comet assay showed that all 5 draining waters were genotoxic after 1 d of exposure. Although 3 of them were still genotoxic after 12 d of exposure, DNA damage globally decreased between d 1 and 12. The comet assay can be considered as a genotoxicity-screening tool. Data indicate that both tests should be used in conjunction in Xenopus. Bacterial tests (Ames) revealed genotoxicity for only one draining water. The results confirm the relevance of the amphibian model and the need to resort to bioassays in vivo such as the Xenopus micronucleus and comet assays for evaluation of the ecotoxicological impact, an essential complement to the physicochemical data.

Comparative study of the comet assay and the micronucleus test in amphibian larvae (Xenopus laevis) using benzo(a)pyrene, ethyl methanesulfonate, and methyl methanesulfonate: establishment of a positive control in the amphibian comet assay

The present investigation explored the potential use of the comet assay (CA) as a genotoxicity test in the amphibian Xenopus laevis and compared it with the French standard micronucleus test (MNT). Benzo[a]pyrene (B[a]P), methyl methanesulfonate (MMS), and ethyl methanesulfonate (EMS) were used as model compounds for assessing DNA damage. Damage levels were measured as DNA strand breaks after alkaline electrophoresis of nuclei isolated from larval amphibian erythrocytes using the CA in order to establish a positive control for further ecotoxicological investigations. The results led to the selection of MMS as a positive control on the basis of the higher sensitivity of Xenopus laevis to this compound. The CA and MNT were compared for their ability to detect DNA damage with the doses of chemical agents and exposure times applied. EMS and MMS were shown to increase micronucleus and DNA strand break formation in larval erythrocytes concurrently. However, B[a]P increased micronucleus formation but not that of DNA strand breaks. Time-dose experiments over 12 days of exposure suggest that the CA provides an earlier significant response to genotoxicants than does the MNT. In Xenopus the CA appears to be a sensitive and suitable method for detecting genotoxicity like that caused by EMS and MMS. It can be considered a genotoxicity-screening tool. The results for B[a]P show that both tests should be used in a complementary manner on Xenopus.

Toxic effects of some major polyaromatic hydrocarbons found in crude oil and aquatic sediments on Scenedesmus subspicatus

The green alga, Scenedesmus subspicatus was exposed for 7 days to a series of PAHs (polyaromatic hydrocarbons) of increased molecular weight from two to five rings [naphthalene (Nap), anthracene (Ant), phenanthrene (Phe), pyrene (Pyr) and benzo(a)pyrene (BaP)]. The toxicity measured as population growth inhibition by individual PAH to the S. subspicatus followed the order: BaP>Pyr>Ant>Phe>Nap. These results confirmed that the toxicity potential of PAHs seems to be strongly influenced by their physico-chemical properties (aqueous solubility, K(ow), coefficient of volatilization, etc.) and the conditions of algae culture (light, presence of nitrate ions, etc.). Consequently, Nap, Phe and Ant having low k(ow) values and low coefficient of volatilization values were less toxic than BaP with the highest k(ow) value, indicating for example why Nap with the lowest EC(50) value was nearly 2 x 10(5) times lower than that of BaP. Moreover, nitrate ions seemed to act directly on the degree of hydroxylated radical reactivity of PAHs, since BaP always remained the most toxic of the compounds tested. The results were also agreed with the QSAR model for toxicity prediction of PAHs to many aquatic organisms.

Evaluation of toxic and genotoxic potential of stabilized industrial waste and contaminated soils

Artificial aqueous samples (eluates, percolates, immersion waters) were obtained from contaminated soils and stabilized industrial wastes. The toxicity and genotoxicity of these aqueous fractions have been evaluated in vivo in the aquatic larvae of the amphibian Xenopus laevis. Four biotests have been applied: a test of subchronic toxicity and three biomakers: (1) measurement of the activity of ethoxyresorufine-o-dealkylase in the liver, (2) detection of DNA adducts in the liver and the blood, and (3) measurement of the rate of micronuclei in the erythrocytes. Biological datas were completed through a chemical analysis. The main conclusions of this study are: The importance of integrating different toxicity criterias into a biological battery (phenotypic and genotypic criterias). Some aqueous extracts did not seem to be very toxic, whereas their genotoxic effects were rather significant [e.g. the stabilized Municipal Solid Waste (MSW) ashes]. The importance of coupling together chemical and biological approaches to refine the impact. Actually, some eluates (lixiviation or percolation) coming from polluted soils appeared to be very poorly loaded with pollutants, whereas the toxic and genotoxic impact of these complex matrices were rather noticeable. In addition, when applying the leaching standardized procedure, the hazardous potential of the two analysed soils may be underestimated if the results on percolates and on eluates have been compared. This study highligths the importance of coupling the tools of characterization and preparation of samples to be analysed according to the objectives to be reached.

Accumulation kinetics of polycyclic aromatic hydrocarbons adsorbed to sediment by the mollusk Corbicula fluminea

The accumulation kinetics in the freshwater mollusk Corbicula fluminea were measured for sediment-associated selected polycyclic aromatic hydrocarbons (PAHs), namely, anthracene (Ant), phenanthrene (Phe), pyrene (Pyr), and benzo [a] pyrene (BaP). The desorption from sediment to water was not only related to water solubility, but also depended on structural and physicochemical properties of PAHs (molecular weight, molecular area, octanol/water partition coefficient Kow). Uptake of PAHs by mollusks was very fast in the first 24 h and maximum for low-molecular-weight compounds. Then animal concentrations decreased significantly after the first day for Ant and Phe, after the second day for Pyr, and after the second week for BaP (at this time the BaP concentration was higher than concentrations of the other PAHs). The kinetic data suggest that PAH uptake is related to desorption from sediment particles. Log PAH uptake is inversely related to log Kow. Bioavailability of sediment-sorbed PAHs declined with contact time between sediment and animals. Assimilation from ingested material may be significant for the more strongly sorbed compound (BaP). PAHs with low Kow values become biologically unavailable more rapidly and more efficiently excreted.

In vivo metabolism of benzo(a)pyrene in a lower vertebrate, the newt Pleurodeles walt

The capacity of the newt to metabolize benzo(a)pyrene in vivo was investigated qualitatively and quantitatively: metabolism was found to be rapid. Treatment of bile with beta-glucuronidase and aryl-sulfatase released high proportions of diols and quinones. 3-Methylcholanthrene treatment shortened the elimination half-life of benzo(a)pyrene which was about three times shorter than the half-life found for non-3-methylcholanthrene-pretreated animals. Thus, a greater proportion of benzo(a)pyrene was converted into water-soluble products.

Amphibian micronucleus test in vivo: evaluation of the genotoxicity of some major polycyclic aromatic hydrocarbons found in a crude oil

The micronucleus test using erythrocytes of Pleurodeles waltl larvae (Amphibia, Salamandridae) was used to detect the possible genotoxicity of four polycyclic aromatic hydrocarbons (naphthalene, anthracene, phenanthrene and benzo[a]pyrene), which represent a major fraction of crude oil. Larvae were reared in water containing the test compound and the levels of micronucleated red blood cells were compared with those found in larvae reared in control water. The results are compared with published data from other tests used to evaluate the clastogenic or mutagenic properties of compounds. The results obtained confirm that benzo[a]pyrene has a strong genotoxic potential, whereas the genotoxicity of naphthalene is weak; in contrast, anthracene and phenanthrene gave a negative response.

In vivo detection of waste water and industrial effluent genotoxicity: use of the Newt Micronucleus Test (Jaylet Test)

The genotoxic potential of various waste waters has been evaluated in a micronucleus test using amphibian larvae. Genotoxicity was detected after dilution, in waste water from tanneries and from various petrochemical industries. Further studies have shown that sample treatment used for in vitro testing may affect the genotoxic response. Sterilization by gamma irradiation lowered genotoxic activity. Furthermore, microfiltration of effluent and extraction of organic micropollutants on XAD-4 resins, lead to the preparation of extracts which are not fully representative of the initial water sample. Testing of concentrates, as required for in vitro studies, will limit the scope of a survey to that part of the organic matter that can be recovered by concentration techniques. Many of the problems encountered in in vitro genotoxicity studies of waters, may be circumvented with direct testing on aquatic organisms. Thus, there is no need to concentrate or sterilise a sample. The tests can be carried out with intact animals, thus taking into account uptake and elimination, internal transport and metabolism. Finally, in vivo test-systems, such as the Newt Micronucleus Test, are more relevant to eukaryotes than bacterial assays and are suitable to assess the real impact of genotoxins discharged in the aquatic environment.

A new micronucleus test using peripheral blood erythrocytes of the newt Pleurodeles waltl to detect mutagens in fresh-water pollution

A model micronucleus test system using peripheral blood erythrocytes from larvae of Pleurodeles waltl is described. The most suitable larval stage for testing chemical treatments was determined. Larvae were reared in water containing one of the 4 compounds: benzo[a]pyrene (BaP), ethyl methanesulphonate (EMS), diethyl sulphate (DES) and N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG). Response curves as a function of treatment duration over a period of 16 days were plotted for 3 different concentrations of the 4 compounds in order to optimize conditions for a low dose micronucleus test. This model can be used as a monitoring system for the detection of fresh water pollution and can also be employed for clastogen screening of chemical compounds. The test is sensitive, reliable and easy to use.

Maternal effect and embryonic gene expression for lactate dehydrogenase B (LDH-B), glucose-6-phosphate dehydrogenase (G6PDH), and peptidase (PEP-1) during the development of Pleurodeles waltl (urodele amphibian)

The polymorphism of three enzymes [lactate dehydrogenase B (LDH-B), glucose-6-phosphate dehydrogenase, (G6PDH), and peptidase-1 (PEP-1)] in Pleurodeles waltl has allowed the expression of the corresponding loci to be followed during the development of spawnings arising from various crosses. A maternal effect lasting up to the late tail-bud stage (approx. stage 28) was shown for PEP-1. A similar situation was observed for LDH-B and G6PDH. The embryonic alleles present retarded expression: from about stage 28 for PEP-1 and G6PDH and from about stages 22 to 24 (the young tail-bud stage) for LDH-B.

A genetic study of various enzyme polymorphisms in Pleurodeles waltlii (Urodele, Amphibian). III. The relationship between sex-linked peptidase-1 expression and gene-dose effects

Erythrocyte peptidase-1 was analyzed by electrophoresis in various types of triploid Pleurodeles waltlii. Densitometric analysis of the zymograms showed (1) the existence of a gene-dose effect and (2) the presence of two Pep-1B alleles for one Pep-1A allele in heterozygous triploid females of biparental origin. Owing to the sex linkage of the PEP-1 locus (alleles Pep-1A and Pep-1B situated on the Z and W sex chromosomes, respectively), the results show that the sex genotype of these females is ZWW. In a particular line called series 103, the existence of a null allele was demonstrated. Densitometric analysis of females which were Pep-1A/Pep-10 (ZW), Pep-10/Pep-10 (WW), and Pep-1A/Pep-10/Pep-10 (ZWW) confirmed the gene-dose effect.

A genetic study of various enzyme polymorphisms in Pleurodeles waltlii (Urodele amphibian). I. Lactate dehydrogenase-B and glucose-6-phosphate dehydrogenase

On starch gel electrophoresis of erythrocyte hemolysates of Pleurodeles waltlii (Urodele Amphibian), both lactate dehydrogenase-B (LDH-B) and glucose-6-phosphate dehydrogenase (G6PDH) show polymorphism that depends on a pair of autosomal codominant alleles, confirmed by analysis of gynogenesis progeny. Diploid gynogenesis results from fusion of the female pronucleus with the second polar body. The heterozygous state of a female for a given character is maintained in certain progeny when crossing-over occurs between the locus in question and the centromere. So the high proportion of heterozygotes (45.7% for LDH-B and 76% for G6PDH) indicates the high frequency of crossing-over and hence the large distance between each of the loci and the centromere.

A genetic study of various enzyme polymorphisms in Pleurodeles waltlii (Urodele Amphibian). II. Peptidases: demonstration of sex linkage

The existence of four peptidases was demonstrated by starch gel electrophoresis in Pleurodeles waltlii: PEP-1, PEP-2, PEP-3, and PEP-4. Peptidases-3 and -4 are monomorphic, and peptidases-1 and -2 are polymorphic. The heredity of the polymorphisms was studied using individuals arising from crosses or of gynogenetic origin. Peptidase-1 is dimeric; its polymorphism depends on a pair of codominant alleles, Pep-1A and Pep-1B, which are situated on the Z and W sex chromosomes, respectively, in close proximity to, or even within, the sex differential segment. As the differential segment is very close to the centromere, the PEP-1 locus therefore also appears to be closely linked to it. Expression of the PEP-1 locus was shown to be independent of the sex hormone environment. This locus is the first case reported in amphibians of an enzyme marker linked to the genetic sex. It allows the sex of PLeurodeles to be determined before they reach sexual maturity. Peptidase-2 is monomeric. Its polymorphism depends on a pair of codominant alleles on an autosomal PEP-2 locus. The high proportion of heterozygous animals in the gynogenetic offspring of females heterozygous for the PEP-2 locus indicates segregation which is independent of the centromere. Analysis of the offspring of doubly heterozygous females (i.e., for two of the loci--LDH-B, G6PDH, PEP-1, and PEP-2) shows that the four loci are independent.

Induction of triploidy in the newt Pleurodeles waltlii by heat shock or hydrostatic pressure: interpretation of the different types of ploidy using a chromosomal marker

Eggs of diploid females of Pleurodeles waltii, fertilized artificially by waltlii sperm, have been submitted to increased temperature of hydrostatic pressure during the first hour of development. Of the resulting viable individuals about 95% were triploid, the remainder diploid or tetraploid. Other types of ploidy have been observed in abnormal embryos (n, 2n/4n, 5n, n/5n, 6n). Some of the treated eggs came from females with a marker chromosome (pericentric inversion). The karyotypes of the animals developing from such eggs confirm that triploidy results from retention of the second polar body and make it possible to interpret the origin of the other types of ploidy. From the results it can be envisaged how gynogenetic animals can be obtained from eggs inseminated by inactivated sperm and shock-treated to restore diploidy.

Experimental gynogenesis in the newt species Pleurodeles waltlii and P. poireti

Eggs of diploid females of Pleurodeles waltlii, inseminated by genetically inactivated sperm of Salamandra salamandra, have been treated by heat-shock or increased hydrostatic pressure during the first hour of their development. The resulting viable gynogenetic individuals show different degrees of ploidy although they mostly are diploid. The use of females with a pericentric inversion as a marker chromosome allow the chromosomal constitution to be clarified. Eggs of females heterozygous for a recessive semilethal mutation (ascite caudale, ac) subjected to the same experimental treatment gave 50% ac/ac embryos. Experiments with Pleurodeles poireti gave the same results as those with P. waltlii. These observations prove that gynogenetic Urodeles can be produced in large numbers. In their offspring the detection of inherent or spontaneous recessive mutations is greatly facilitated.