One family in two countries: mothers in Korean transnational families

This qualitative study explores Korean transnational families, known as gireogi gah-jok. In this type of family, the mother and her children move to an English-speaking country for the children's education while the father stays and supports his family financially from the country of origin. We conducted interviews with thirteen mothers who resided with at least one adolescent child in the northwest area of the USA. Guided by symbolic interactionism, we examined how women perceived the gireogi family situation separated in the two countries and how their perception influenced their maternal roles as gireogi mothers. Findings indicate that these women reshaped their maternal self and renegotiated gendered roles in response to their residence in the foreign country and physical separation from their husbands. The findings also suggest that participants made an effort to maintain family cohesion by frequent communication using technology and sporadic reunions.     

The genetic legacy of Mother Goose– phylogeographic patterns of lesser snow goose Chen caerulescens caerulescens maternal lineages

By using the polymerase chain reaction to amplify and sequence 178 bp of a rapidly evolving region of the mtDNA genome (segment I of the control region) from 81 individuals, approximately 11% of the variation present in the lesser snow goose Chen caerulescens caerulescens L. mitochondrial genome was surveyed. The 26 types of mtDNA detected formed two distinct mitochondrial clades that differ by an average of 6.7% and are distributed across the species range. Restriction analysis of amplified fragments was then used to assign the mtDNA of an additional 29 individuals to either of these clades. Within one major clade, sequence among mtDNAs was concordant with geographic location. Within the other major clade the degree of sequence divergence among haplotypes was lower and no consistent geographic structuring was evident. The two major clades presumably result from vicariant separation of lesser snow geese during the Pleistocene.     

Towards an integrated linkage map of common bean 2. Development of an RFLP-based linkage map

Summary A restriction fragment length polymorphism (RFLP)-based linkage map for common bean (Phaseolus vulgaris L.) covering 827 centiMorgans (cM) was developed based on a F₂ mapping population derived from a cross between BAT93 and Jalo EEP558. The parental genotypes were chosen because they exhibited differences in evolutionary origin, allozymes, phaseolin type, and for several agronomic traits. The segregation of 152 markers was analyzed, including 115 RFLP loci, 7 isozyme loci, 8 random amplified polymorphic DNA (RAPD) marker loci, and 19 loci corresponding to 15 clones of known genes, 1 virus resistance gene, 1 flower color gene, and 1 seed color pattern gene. Using MAPMAKER and LINKAGE-1, we were able to assign 143 markers to 15 linkage groups, whereas 9 markers remained unassigned. The average interval between markers was 6.5 cM; only one interval was larger than 30 cM. A small fraction (9%) of the markers deviated significantly from the expected Mendelian ratios (121 or 31) and mapped into four clusters. Probes of known genes belonged to three categories: seed proteins, pathogen response genes, and Rhizobium response genes. Within each category, sequences homologous to the various probes were unlinked. The I gene for bean common mosaic virus resistance is the first disease resistance gene to be located on the common bean genetic linkage map.     

Characterisation and genetic diversity of pepper leafroll virus,a new bipartite begomovirus infecting pepper,bean and tomato in Peru

The complete genome of a novel bipartite begomovirus (genus Begomovirus, family Geminiviridae) was cloned from a severely diseased yellow Peruvian chili pepper (Capsicum baccatum cv. Pendulum) plant collected in the department of La Libertad, Northern Peru and full‐length sequenced. The two genomic components share a common region of 156 nucleotides with a 100% sequence identity. Analysis of the genome organisation and phylogenetic comparisons revealed that the virus is a typical New World begomovirus. The closest related begomovirus, an isolate of Tomato yellow vein streak virus (ToYVSV), shared only 76.8% nucleotide sequence identity for the DNA‐A component. Therefore, following species demarcation criteria of the International Committee on Taxonomy of Viruses, this virus isolate belongs to a new begomovirus species for which the name pepper leafroll virus (PepLRV) is proposed. Pepper plants infected with the cloned PepLRV isolate developed leaf roll symptoms similar to those observed in field‐infected plants suggesting this virus as the causal agent of the disease syndrome observed in the field. Widespread occurrence of PepLRV throughout Peru was demonstrated, infecting plants of diverse cultivated species such as tomato, pepper, common and pallar beans, and of the weed species Nicandra physaloides. Low genetic diversity was observed among PepLRV isolates present in this country with no evident geographical or temporal structure of the population, typical of a recent founder effect. This is the first report of a begomovirus infecting pepper and bean crops in Peru.     

Aphid behavioral responses to virus‐infected plants are similar despite divergent fitness effects

We compared the settling preferences and reproductive potential of an oligophagous herbivore, the pea aphid, Acyrthosiphon pisum Harris (Hemiptera: Aphididae), in response to pea plants, Pisum sativum L. cv. ‘Aragorn’ (Fabaceae), infected with two persistently transmitted viruses, Pea enation mosaic virus (PEMV) and Bean leaf roll virus (BLRV), that differ in their distribution within an infected plant. Aphids preferentially oriented toward and settled on plants infected with PEMV or BLRV in comparison with sham‐inoculated plants (plants exposed to herbivory by uninfected aphids), but aphids did not discriminate between plants infected with the two viruses. Analysis of plant volatiles indicated that plants inoculated with either virus had significantly higher green leaf volatile‐to‐monoterpene ratios. Time until reproductive maturity was marginally influenced by plant infection status, with a trend toward earlier nymph production on infected plants. There were consistent age‐specific effects of plant infection status on aphid fecundity: reproduction was significantly enhanced for aphids on BLRV‐infected plants across most time intervals, though mean aphid fecundity did not differ between sham and PEMV‐infected plants. There was no clear pattern of age‐specific survivorship; however, mean aphid lifespan was reduced on plants infected with PEMV. Our results are consistent with predictions of the host manipulation hypothesis, extended to include plant viruses: non‐viruliferous A. pisum preferentially orient to virus‐infected host plants, potentially facilitating pathogen transmission. These studies extend the scope of the host manipulation hypothesis by demonstrating that divergent fitness effects on vectors arise relative to the mode of virus transmission.     

Effect of aggregation on the reproductive rate of populations

The effect of spatial distribution on the reproductive rate of a population was examined by applying an approximate equation to several data based on the entomological literature. This study suggests that aggregation generally reduces the equilibrium level of the population density if the population density is not very high.     

Heat-induced reversible and irreversible alterations in the structure of phaseolus vulgaris thylakoid proteins

Chloroplast thylakoids isolated from bean (Phaseolus vulgaris L.) leaves have been used as a model system to identify heat-induced changes in membrane protein structure. Susceptibility of SDS gel electrophoresis bands to trypsin digestion was used as an assay for altered structure of proteins comprising the bands. Both reversible and irreversible alternations in membrane protein structure have been observed as a result of exposure to 35 or 45°C for varying time periods.     

胰岛素对鹅原代肝细胞增殖及蛋白合成的影响

通过用不同浓度胰岛素培养天府肉鹅（Ansercygnoides）原代肝细胞探讨胰岛素对鹅原代肝细胞增殖及蛋白合成的影响。结果表明：与对照组相比,0—200nmol／L胰岛素对肝细胞上清液中谷草转氨酶（AST）、谷丙转氨酶（ALT）浓度没有显著影响,表明细胞功能正常;100、150和200nmol／L胰岛素显著增加细胞培养上清液中总蛋白（什）和白蛋白（ALB）浓度;Brdu．ELISA法检测DNA合成实验结果表明经胰岛素处理后显著增加鹅原代肝细胞增殖率。因此,胰岛素能促进鹅原代肝细胞的细胞增殖及蛋白合成。     

Mechanism of DNA cleavage catalyzed by Mung Bean Nuclease

The interaction of zinc with different forms of DNA (λ phage DNA, ss-oligo, ds-oligo) and Mung Bean Nuclease was studied by voltammetric techniques in order to investigate the mechanism of DNA cleavage catalyzed by a zinc metalloenzyme. Stoichiometry, dissociation constant, zinc binding sites and functions were determined for these systems. Two zinc ions were found to be involved in stabilization of a 19 mer ds-oligodeoxyribonucleotide, which was synthesized by the phosphoramidite method and used as a DNA model in the studies. Three zinc ions (Zn1, Zn2, and Zn3), which have different roles in ds-oligo cleavage, were identified in the active site of Mung Bean Nuclease. A concerted S_N2 mechanism, which assigns a catalytic function to Zn2 and structural functions to Zn1 and Zn3, was proposed. The hydrolysis of phosphodiester bonds proceeds with inversion of configuration at the phosphorus center, forming a pentacoordinate transition state, which is stabilized by an arginine. Zn2 supplies the nucleophile, which is oriented by an aspartic acid, and activates the ds-oligo by its coordination to the phosphate free oxygen of the phosphodiester bond. Zn1 and Zn3 ions, besides stabilizing the tertiary structure of Mung Bean Nuclease, bind to the leaving group, blocking the cleavage reverse reaction.