Correction of Defective Early Tyrosinase Processing by Bafilomycin A1 and Monensin in Pink‐Eyed Dilution Melanocytes

Mutations in the human P gene result in oculocutaneous albinism type 2, the most common form of albinism. Mouse melan‐p1 melanocytes, cultured from mice null at the homologous pink‐eyed dilution (p) locus, exhibit defective melanin production. A variety of compounds including tyrosine, NH₄Cl, bafilomycin A1, concanamycin, monensin, and nigericin are capable of restoring melanin synthesis in these cells. In the current study, we investigated the subcellular effects of bafilomycin A1 and monensin treatment of melan‐p1 cells. Both agents play two roles in the processing of tyrosinase (Tyr) in melan‐p1 cells. First, combined glycosidase digestion and immunoblotting analysis showed that these agents reduce levels of Tyr retained in the endoplasmic reticulum (ER) and facilitate the release of Tyr from the ER to the Golgi. Secondly, treatment with these compounds resulted in the stabilization of Tyr. Surprisingly, induction of melanin synthesis corresponds more closely with diminution of ER‐retained Tyr, rather than the absolute amount of Tyr. Our results suggest that bafilomycin A1 and monensin induce melanin synthesis in melan‐p1 cells mainly by facilitating Tyr processing from the ER to the Golgi by increasing the pH in either the ER or the ER–Golgi intermediate compartment.     

Impact of abscisic acid in overcoming the problem of albinism in horse chestnut androgenic embryos

Horse chestnut (Aesculus hyppocastanum L., Hyppocastanacea) is a relict species with a slow and complex reproductive cycle considered to have horticultural and medical importance. The cycle maybe circumvented via in vitro androgenesis. Androgenesis of horse chestnut was induced in microspores and anther culture on MS media. Some of the horse chestnut androgenic embryos were albinos. Addition of abscisic acid in media (in concentrations of 0.01, 0.1, 0.5, 1, 2, 5, 10, and 20 mg l^?1) with horse chestnut androgenic embryos has circumvented the reproduction cycle barriers. The best results were achieved on medium with the lowest abscisic acid concentration (0.01 mg l^?1) in microspore culture. The microspore culture proved to be a better model system for embryo production and albino embryo reduction than anther culture. Flow cytometry analysis after maturation treatments induced by ABA showed that 88 % of green embryos originating from microspore culture were haploid. However, 50 % of green embryos from anther culture were haploid. The remaining analyzed androgenic embryos, from both types of cultures were diploid.     

Allozyme diversity in pheasants (<Emphasis Type="Italic">Phasianus</Emphasis> spp.) from breeding stations in Serbia

The pheasant breeds are widely used for restocking of natural populations depleted by hunting. The pheasant population number decline was detected during the 1970s in many hunting areas of Europe. One of its possible reasons might be the loss of adaptability in populations originating from breeding stations, which was caused by inbreeding depression. The aim of this paper was the analysis of genetic variability in pheasant populations from three breeding stations in Vojvodina province (Serbia) by means of allozyme diversity detection. The allozyme variability analysis of pheasants from all three breeding stations revealed polymorphisms at nine loci: Ldh-1, Mor-1, Mor-2, Es-1, Mod-2, Pgd, Gpi-2, Odh, and Sod. The analysis of individuals from three different breeding stations showed mean values of observed heterozygosity of H _o=0.137, polymorphism P _95%=30%, and H/P ratio H/P=0.430, which indicate a normal level of genetic variability for bird populations. Comparative analysis of three pheasant populations showed a high level of interpopulation differentiation.     

Reptile Ownership in Balkan Countries: Demographics and Reliance on Veterinary Advice

The objective of the research was to determine the profile of reptile owners (n = 238) in terms of their socio-demographic characteristics and evaluations of veterinarians’ expertise. Reptile owners living in four non-EU Balkan countries (Bosnia and Herzegovina, Macedonia, Montenegro, and Serbia) were randomly selected from two social networks. Statistically significant differences were found in snake, lizard, and turtle owners (p < 0.05) in terms of gender, employment status, and monthly earnings. Male owners of reptiles were slightly more numerous (52%) compared with female owners (48%). Sixty-four percent of reptile owners were over 20 years old. The unemployed reptile owners (16%) were about five times fewer in number compared with those who studied at university and those who were employed. Forty-one percent of reptile owners declared high monthly incomes. Forty percent of reptile owners never contacted and had no experience with veterinarians. Fifty-eight percent of reptile owners contacted or visited veterinarians due to the medical condition of their animals, 14% of them contacted veterinarians for advice on reptile keeping, and only 6% did so for a preventive veterinary examination. Forty-seven percent of reptile owners were satisfied with veterinary services. The importance of the results of this survey is that they can provide a basis for adopting legislation on the ownership of reptiles as pet animals, together with being a baseline for monitoring subsequent changes in interest in these animals as pets. The results also identify the need for more dedication from veterinarians in educating reptile owners, and for necessary adjustments in veterinary education.     

Synthetic circuits reveal how mechanisms of gene regulatory networks constrain evolution

Phenotypic variation is the raw material of adaptive Darwinian evolution. The phenotypic variation found in organismal development is biased towards certain phenotypes, but the molecular mechanisms behind such biases are still poorly understood. Gene regulatory networks have been proposed as one cause of constrained phenotypic variation. However, most pertinent evidence is theoretical rather than experimental. Here, we study evolutionary biases in two synthetic gene regulatory circuits expressed in Escherichia coli that produce a gene expression stripe—a pivotal pattern in embryonic development. The two parental circuits produce the same phenotype, but create it through different regulatory mechanisms. We show that mutations cause distinct novel phenotypes in the two networks and use a combination of experimental measurements, mathematical modelling and DNA sequencing to understand why mutations bring forth only some but not other novel gene expression phenotypes. Our results reveal that the regulatory mechanisms of networks restrict the possible phenotypic variation upon mutation. Consequently, seemingly equivalent networks can indeed be distinct in how they constrain the outcome of further evolution.     

An azhdarchid humerus (Pterosauria,Azhdarchidae) from the Upper Cretaceous of Saratov Region

A proximal humerus fragment referred to as Azhdarchidae indet. from the Rybushka Formation (Upper Cretaceous, Lower Campanian) of the Beloe Ozero locality in Saratov Region is described. The proximal articular surface is not saddle-shaped, has a weakly convex profile in the frontal section. The most posteriorly projecting part of the proximal articular surface is displaced ventrally. A large pneumatic foramen is located on the anterior surface ventral to the base of deltopectoral crest and close to the proximal articular surface. The humeral head is slightly declined from the diaphysis and only slightly overhangs the diaphysis posteriorly. This proximal humerus fragment possibly belongs to Volgadraco bogolubovi Averianov, Arkhangelsky et Pervushov, 2008, described from the Rybushka Formation of the Shirokii Karamysh 2 locality in Saratov Region.