Independent Transport and Sorting of Functionally Distinct Protein Families in Tetrahymena thermophila Dense Core Secretory Granules

Dense core granules (DCGs) in Tetrahymena thermophila contain two protein classes. Proteins in the first class, called granule lattice (Grl), coassemble to form a crystalline lattice within the granule lumen. Lattice expansion acts as a propulsive mechanism during DCG release, and Grl proteins are essential for efficient exocytosis. The second protein class, defined by a C-terminal beta/gamma-crystallin domain, is poorly understood. Here, we have analyzed the function and sorting of Grt1p (granule tip), which was previously identified as an abundant protein in this family. Cells lacking all copies of GRT1, together with the closely related GRT2, accumulate wild-type levels of docked DCGs. Unlike cells disrupted in any of the major GRL genes, Delta GRT1 Delta GRT2 cells show no defect in secretion, indicating that neither exocytic fusion nor core expansion depends on GRT1. These results suggest that Grl protein sorting to DCGs is independent of Grt proteins. Consistent with this, the granule core lattice in Delta GRT1 Delta GRT2 cells appears identical to that in wild-type cells by electron microscopy, and the only biochemical component visibly absent is Grt1p itself. Moreover, gel filtration showed that Grl and Grt proteins in cell homogenates exist in nonoverlapping complexes, and affinity-isolated Grt1p complexes do not contain Grl proteins. These data demonstrate that two major classes of proteins in Tetrahymena DCGs are likely to be independently transported during DCG biosynthesis and play distinct roles in granule function. The role of Grt1p may primarily be postexocytic; consistent with this idea, DCG contents from Delta GRT1 Delta GRT2 cells appear less adhesive than those from the wild type.

亲子依恋对大学生人际关系影响的性别效应

Parent-child attachment refers to the emotional bond that forms between parent and child, which has great influences on the child’s interpersonal development. Present study applied both correlation method and secure attachment memory activation method to investigate the “gender relation effects” of parent-child attachment’s influences on college students’ close relationships, general attachment representation, and emotion and social loneliness. The basic hypotheses on “gender relation” were set as: “same-sex” parent-child attachment has more influences on college students’ “same-sex” interpersonal relationships, while “opposite-sex” parent-child attachment has more influences on college students’ “opposite-sex” interpersonal relationships. Major findings includes: 1. There was weak correlation of attachment security between father-child and mother-child relationships. The findings indicated that, among college students, the security of “opposite-sex” parent-child attachment representation is higher to some extent than that of “same-sex” parent-child attachment representation. 2. There were significant correlations between parent-child attachment and college students’ attachment anxiety in close relationships. Major findings indicated that “opposite-sex” parent-child attachment security negatively predicts college students’ attachment anxiety in both “same-sex” and “opposite-sex” close relationships. 3. Gender relation effects were significant in the correlations between parent-child attachment and college students’ level of avoidant attachment representation. “Same-sex” parent-child attachment security positively predicted avoidant attachment level in college students’ “same-sex” close relationships, while “opposite-sex” parent-child attachment security positively predicted avoidant attachment level in “opposite-sex” close relationships. 4. Parent-child attachment security memory activation had significant influences on college students’ general attachment representation, in which gender relation effects indicated that: the memory activation of father-child attachment security significantly increases participants’ security of self-model in general attachment representation to “male others”; while the memory activation of mother-child attachment security significantly increase participants’ security of others-model in general attachment representation to “female others”. 5. For male college students, father-son attachment security negatively predicted their emotion and social loneliness. For female college students, father-daughter attachment security negatively predicted their emotion loneliness, while mother-daughter attachment security negatively predicted their social loneliness. Attachment security memory activation had significant influences on college students’ social loneliness, in which gender relation effects was confirmed in that only father-child attachment security memory activation significantly decreased male participants’ level of social loneliness. The results indicated that gender relation effects are significant in the influences of parent-child attachment on college students’ interpersonal relationship representations, especially when the level of avoidant of attachment in college students’ close relationships was predicted by parent-child attachment representation, and when the memory activation of parent-child attachment influenced college students’ general attachment representation. The present study confirmed to some extent that gender relation consistency exists in attachment representations among different interpersonal relations, and serves as a new model for analysis of gender differences in the research fields. In the present study, however, gender relation effects were not confirmed in all the interpersonal relationship representations, which indicated the complexity in the problems of gender differences in the research fields of close relationships.