Sex determination studies in two species of teleost fish, Oreochromis niloticus and Leporinus elongatus

Genetic analyses of sex determination have identified sex chromosomes in many teleost fish species. However, there are several cases for which sex ratios do not fit perfectly with the expectations of heterogametic systems, suggesting the influence of either minor sex determining genes or environmental influences on the process of sex differentiation. The frequent absence of sex chromosome markers makes the identification of minor sex-determining genes very difficult. It is easier to test first the hypothesis of environmental sex determination (ESD) by studying the temperature effect, since temperature-dependent sex determination has been demonstrated to occur in several vertebrate groups including 1 fish species. To contribute to a better understanding of fish sex determination, we have tested the effects of high temperatures on sex ratios of Oreochromis niloticus, and have attempted to isolate sex chromosome molecular markers in Leporinus elongatus. Treatments of O. niloticus fry at 36 degrees C applied for 10 days and more, and starting 1 week after fertilization markedly increased the proportion of males, and progeny-testing these males confirmed that some of them are sex-reversed genetic females. Two non-coding sequences of L. elongatus Z and W chromosomes were cloned by genomic subtraction. They cross-hybridized with the genome of a close species without providing sex-specific patterns. A collection of L. elongates individuals was subjected to gonadal and chromosomal sexing, and DNA hybridization with both sequences. These analyses revealed 3 individuals having atypical W chromosomes. Interestingly, 2 of these were males having a ZW karyotype. We assume that these atypical sex chromosome arise by exchanges between Z and W chromosomes, and that a transition between female and male heterogamety is underway in this species.

Physicochemical parameters involved in the lethal toxicity of N,N-[(dimethylamino)ethyl]-4-substituted benzoate hydrochlorides: A QSAR study

A set of sixteen para-substituted N,N-[(dimethylamino)ethyl] benzoate hydrochlorides structurally related to procaine was synthesized. The apparent partition coefficients were determined by either shake-flask or HPLC methods and were taken as hydrophobic parameters. The IR stretching frequencies of the carbonyl group were determined in chloroform and taken as one of the electronic parameters. Additional physicochemical parameters were either taken from the literature: pi, sigma, T and R, MR4, or calculated: log P. The lethal potency was determined in the mouse via the LD50. In order to verify the nature and the relative contributions of the physicochemical parameters to lethal toxicity, QSAR equations were derived using regression analysis. A major contribution of hydrophobicity to ether with a smaller but still significant contribution of electronic or polar properties was found to a describe the toxicity within this set of compounds.

Treatment of ligature-induced peri-implantitis by lethal photosensitization and guided bone regeneration: A preliminary histologic study in dogs

Background: the purpose of this pilot study was to evaluate the healing potential and reosseointegration in ligature-induced peri-implantitis defects adjacent to various dental implant surfaces following lethal photosensitization.Methods: A total of 36 dental implants with 4 different surface coatings (9 commercially pure titanium surface [CPTi]; 9 titanium plasma-sprayed [TPS]; 9 hydroxyapatite [HA]; and 9 acid-etched [AE]) were inserted in 6 male mongrel dogs 3 months after extraction of mandibular premolars. After a 2-month period of ligature-induced peri-implantitis and 12 months of natural peri-implantitis progression, only 19 dental implants remained. The dogs underwent surgical debridement of the remaining dental implant sites and lethal photosensitization by combination of toluidine blue O (100 mug/ml) and irradiation with diode laser. All exposed dental implant surfaces and bone craters were meticulously cleaned by mechanical means, submitted to photodynamic therapy, and guided bone regeneration (GBR) using expanded polytetrafluoroethylene (ePTFE) membranes. Five months later, biopsies of the implant sites were dissected and prepared for ground sectioning and analysis.Results: the percentage of bone fill was HA: 48.28 +/- 15.00; TPS: 39.54 +/- 12.34; AE: 26.88 +/- 22.16; and CPTi: 26.70 +/- 16.50. The percentage of reosseointegration was TPS: 25.25 +/- 11.96; CPTi: 24.91 +/- 17.78; AE: 17.30 +/- 15.41; and HA: 15.83 +/- 9.64.Conclusion: These data suggest that lethal photosensitization may have potential in the treatment of peri-implantitis.

OXYGEN-CONSUMPTION RELATED TO SIZE AND SEX IN THE TROPICAL MILLIPEDE PSEUDONANNOLENE-TRICOLOR (DIPLOPODA, SPIROSTREPTIDA)

1. The oxygen consumption of the tropical millipede, Pseudonannolene tricolor (Spirostreptida, Pseudonannolenidae) was studied in both male and female animals (body mass varying from 0.242 to 2.802 g) using a Warburg microrespirometer at 25-degrees-C.2. The allometric equation M = a W(b) was used in order to check the metabolic increases with increasing body mass. The b exponents were, respectively, 0.68 for males and 0.60 for females.3. Results are discussed in terms of the meaning of the b values in Diplopoda and animals in general.4. A relationship between volume and body mass in P. tricolor is also reported.

SEX-RELATED DIFFERENCES IN CARDIOVASCULAR-RESPONSES TO COMMON CAROTID OCCLUSION IN CONSCIOUS RATS

Mean arterial pressure and heart rate were determined in conscious, unrestrained groups of 10 male, female and androgenized female Wistar rats 20 s (early pressor response) and 1 min (late sustained response) after bilateral carotid artery occlusion. The early pressor response, which is of carotid reflex origin, was 40% greater in female than in male rats (45 +/- 2 vs 63 +/- 3 mmHg, respectively). The late sustained response, which is of central origin (probably ischemic), did not differ between male and female rats (32 +/- 2 vs 37 +/- 4 mmHg, respectively). The magnitude of the early pressor response of androgenized female tats (50 +/- 2 mmHg) was similar to that of male rats (45 +/- 2 mmHg) but the late sustained response was 19% smaller (26 +/- 2 mmHg). Common carotid occlusion caused increases in heart rate which were greater in female (51 +/- 9 and 34 +/- 9 beats/min in the early pressor response and late sustained response, respectively) than in male rats (31 +/- 5 and 8 +/- 4 beats/min, respectively). In androgenized female rats, heart rate decreased during common carotid occlusion (34 +/- 7 and 35 +/- 8 beats/min after 20 s and 1 min, respectively). These data provide evidence that there are substantial sex-related differences in the cardiovascular responses to common carotid occlusion in conscious rats and indicate that administration of androgens to newborn female rats affects the baroreceptor reflex control of their arterial pressure.

Scent-marking behaviour in free-ranging golden-faced saki monkeys, Pithecia pithecia chrysocephala: Sex differences and context

Scent-marking behaviour of golden-faced saki monkey, Pithecia pithecia chrysocephala, was observed intermittently between 1987 and 1990 for a family group in a Central Amazonian forest fragment. of 95 scent-marking events (during 275.5 hours of observation), throat-and-chest rubbing accounted for all except one anogenital rubbing. Nine of the throat-and-chest markings also involved touching groin with hands and eight markings (including the anogenital), urinating on the marked branch. Marking behaviour is strongly sex related, with the adult male making 88.4% of the markings. Scent-marking frequency by the adult male increased during breeding periods. Scent-marking behaviour seems related to courtship, and possibly stimulates sexual behaviour. All regularly marked spots consisted of horizontal branches on commonly travelled routes. Eleven occurred in feeding trees and lianas, but none in sleeping trees. Scent-marking behaviour in the monkeys studied here was not related to intergroup encounters and probably did not have a territorial function, although it may do so where different groups interact.

Effects of sex and locality on the abundance of lice on the wild rodent Oligoryzomys nigripes

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