Aggregation and retention of human urokinase type plasminogen activator in the yeast endoplasmic reticulum

Background  

Secretion of recombinant proteins in yeast can be affected by their improper folding in the endoplasmic reticulum and subsequent elimination of the misfolded molecules via the endoplasmic reticulum associated protein degradation pathway. Recombinant proteins can also be degraded by the vacuolar protease complex. Human urokinase type plasminogen activator (uPA) is poorly secreted by yeast but the mechanisms interfering with its secretion are largely unknown.     

Life cycle,morphology of developmental stages of Metorchis ussuriensis sp. nov. (Trematoda: Opisthorchiidae), and phylogenetic relationships with other opisthorchiids

The complete life cycle and developmental stages of the fluke, Metorchis ussuriensis sp. nov. (Trematoda, Platyhelminthes), are herein described. The results of the present experiments showed that, for flukes from the Primorsky Region in the Russian southern Far East, the first intermediate hosts are the snails Parafossarulus spiridonovi and Boreoelona ussuriensis, and the second intermediate hosts are freshwater fish, tadpoles, and snails. The definitive host in this experiment was Anas platyrhynchos dom. Morphometric parameters of M. ussuriensis sp. nov. demonstrate similarities with Metorchis taiwanensis, but the two species differ in the sizes of their bodies, sizes of suckers of adult worms, and sizes of cercariae, as well as respective positions of the finfold in cercariae. Phylogenetic reconstructions and genetic distances using the cox1 gene sequences support the conclusion that M. ussuriensis sp. nov. is well distinguished from all other species of the genus Metorchis, while sequences of internal transcribed spacers (ITS1 and ITS2) failed to separate M. ussuriensis sp. nov., Metorchis bilis, and Metorchis xanthosomus. In addition, we sequenced 1,402 bp of the 28SrRNA gene of M. ussuriensis sp. nov. being the first 28S sequences in the genus Metorchis. Comparison to other trematodes suggests that 28SrRNA could proof suitable for the differentiation of trematode species.     

Exogenous selection rather than cytonuclear incompatibilities shapes asymmetrical fitness of reciprocal Arabidopsis hybrids

Reciprocal crosses between species often display an asymmetry in the fitness of F₁ hybrids. This pattern, referred to as isolation asymmetry or Darwin's corollary to Haldane's rule, is a general feature of reproductive isolation in plants, yet factors determining its magnitude and direction remain unclear. We evaluated reciprocal species crosses between two naturally hybridizing diploid species of Arabidopsis to assess the degree of isolation asymmetry at different postmating life stages. We found that pollen from Arabidopsis arenosa will usually fertilize ovules from Arabidopsis lyrata; the reverse receptivity being less complete. Maternal A. lyrata parents set more F₁ hybrid seed, but germinate at lower frequency, reversing the asymmetry. As predicted by theory, A. lyrata (the maternal parent with lower seed viability in crosses) exhibited accelerated chloroplast evolution, indicating that cytonuclear incompatibilities may play a role in reproductive isolation. However, this direction of asymmetrical reproductive isolation is not replicated in natural suture zones, where delayed hybrid breakdown of fertility at later developmental stages, or later‐acting selection against A. arenosa maternal hybrids (unrelated to hybrid fertility, e.g., substrate adaptation) may be responsible for an excess of A. lyrata maternal hybrids. Exogenous selection rather than cytonuclear incompatibilities thus shapes the asymmetrical postmating isolation in nature.     

Electrocardiographic Characterization of Cardiac Hypertrophy in Mice that Overexpress the ErbB2 Receptor Tyrosine Kinase

Electrocardiography is an important method for evaluation and risk stratification of patients with cardiac hypertrophy. We hypothesized that the recently developed transgenic mouse model of cardiac hypertrophy (ErbB2^tg) will display distinct ECG features, enabling WT (wild type) mice to be distinguished from transgenic mice without using conventional PCR genotyping. We evaluated more than 2000 mice and developed specific criteria for genotype determination by using cageside ECG, during which unanesthetized mice were manually restrained for less than 1 min. Compared with those from WT counterparts, the ECG recordings of ErbB2^tg mice were characterized by higher P- and R-wave amplitudes, broader QRS complexes, inverted T waves, and ST interval depression. Pearson''s correlation matrix analysis of combined WT and ErbB2^tg data revealed significant correlation between heart weight and the ECG parameters of QT interval (corrected for heart rate), QRS interval, ST height, R amplitude, P amplitude, and PR interval. In addition, the left ventricular posterior wall thickness as determined by echocardiography correlated with ECG-determined ST height, R amplitude, QRS interval; echocardiographic left ventricular mass correlated with ECG-determined ST height and PR interval. In summary, we have determined phenotypic ECG criteria to differentiate ErbB2^tg from WT genotypes in 98.8% of mice. This inexpensive and time-efficient ECG-based phenotypic method might be applied to differentiate between genotypes in other rodent models of cardiac hypertrophy. Furthermore, with appropriate modifications, this method might be translated for use in other species.Abbreviations: HCM, hypertrophic cardiomyopathy; LV, left ventricle; QT_c, QT interval corrected for heart rateElectrocardiography is an important method used in human patients for evaluation of cardiac hypertrophy, for example, hypertrophic cardiomyopathy (HCM).^30,35 Although echocardiography is considered to be the ‘gold standard’ in HCM diagnostics, ECG evaluation may provide additional information needed for diagnosis.³⁰ In some patients with HCM, ECG changes precede echocardiographic changes;^30,36 therefore the 2 modalities are often used together to screen family members of patients with HCM. Similarly, there are reports of athletes who suddenly die during training, in whom HCM was confirmed at autopsy and in whom ECG abnormalities were recorded in the absence of overt clinical signs.²³ In contrast, although developed before echocardiography, ECG is often underutilized in the characterization of mouse models of cardiac disease.The first reports on mouse ECG were published in the 1950s^15,40 and were followed by the rapid development of rodent ECG methods, recording, and analysis.¹⁶ Several approaches support the recording and analysis of mouse ECG, including 12-lead ECG,^7,51 open-chest models,^7,51 telemetry using radiofrequency transmitters,¹⁶ and recording in anesthetized mice.^7,51 All of these methods provide information on cardiac electrophysiology, yet each has its specific advantages and limitations.⁵¹ Further use of ECG in mouse models of cardiac disease could improve our understanding of the electrophysiologic remodeling in these diseases.Several mouse models of HCM (due to genetic modifications of genes related to human HCM^18,21,50 or to lysosomal storage disease-related cardiomyopathies^2,4,6,46) were developed to study these hypertrophic conditions and the resulting electrical disturbances in the myocardium. However, despite carrying the same genetic alterations that cause human disease, many mouse models do not have phenotypic ECG changes or even hypertrophy.^18,21,50 Therefore the development of a small animal model of cardiac hypertrophy with ECG features similar to those in human patients is of particular interest. We recently developed a mouse model with cardiac hypertrophy and pathologic features compatible with HCM⁴⁷ and hypothesized that various electrocardiographic features could enable us to distinguish between wildtype (WT) mice and transgenic littermates after weaning. In the current study, we established an ECG method that identifies the hypertrophic phenotype and thus assists in determining the genotype of mice. This ECG method thus reduced laboratory costs and the time necessary to isolate and analyze DNA for genotyping.     

A First Generation Comparative Chromosome Map between Guinea Pig (Cavia porcellus) and Humans

The domesticated guinea pig, Cavia porcellus (Hystricomorpha, Rodentia), is an important laboratory species and a model for a number of human diseases. Nevertheless, genomic tools for this species are lacking; even its karyotype is poorly characterized. The guinea pig belongs to Hystricomorpha, a widespread and important group of rodents; so far the chromosomes of guinea pigs have not been compared with that of other hystricomorph species or with any other mammals. We generated full sets of chromosome-specific painting probes for the guinea pig by flow sorting and microdissection, and for the first time, mapped the chromosomal homologies between guinea pig and human by reciprocal chromosome painting. Our data demonstrate that the guinea pig karyotype has undergone extensive rearrangements: 78 synteny-conserved human autosomal segments were delimited in the guinea pig genome. The high rate of genome evolution in the guinea pig may explain why the HSA7/16 and HSA16/19 associations presumed ancestral for eutherians and the three syntenic associations (HSA1/10, 3/19, and 9/11) considered ancestral for rodents were not found in C. porcellus. The comparative chromosome map presented here is a starting point for further development of physical and genetic maps of the guinea pig as well as an aid for genome assembly assignment to specific chromosomes. Furthermore, the comparative mapping will allow a transfer of gene map data from other species. The probes developed here provide a genomic toolkit, which will make the guinea pig a key species to unravel the evolutionary biology of the Hystricomorph rodents.