The major human and mouse granzymes are structurally and functionally divergent

Approximately 2% of mammalian genes encode proteases. Comparative genomics reveals that those involved in immunity and reproduction show the most interspecies diversity and evidence of positive selection during evolution. This is particularly true of granzymes, the cytotoxic proteases of natural killer cells and CD8+ T cells. There are 5 granzyme genes in humans and 10 in mice, and it is suggested that granzymes evolve to meet species-specific immune challenge through gene duplication and more subtle alterations to substrate specificity. We show that mouse and human granzyme B have distinct structural and functional characteristics. Specifically, mouse granzyme B is 30 times less cytotoxic than human granzyme B and does not require Bid for killing but regains cytotoxicity on engineering of its active site cleft. We also show that mouse granzyme A is considerably more cytotoxic than human granzyme A. These results demonstrate that even “orthologous” granzymes have species-specific functions, having evolved in distinct environments that pose different challenges

STestMAP as an alternative for significance test selection / Tang Howe Eng... [et al.]

One major problem faced by many researchers and students when confronted with the hypothesis testing procedure is to select the relevant statistical test for the purpose of calculating the test statistics. This study aims to determine the effectiveness of STestMAP as a tool to help in the selection of the significance test. It also aims at investigating the flexibility afforded by the STestMAP procedure in catering to the needs of both linear and non-linear users. The research design divides the study into two phases: Phase I where quantitative analysis dominates while Phase II involves qualitative analysis. Four instruments, which consisted of prior knowledge test, pre-test, post-test and interview, were adopted and administered. Data collection was carried out through paper-and-pencil tests and interviews. Both quantitative (descriptive and inferential analyses) and qualitative data analysis techniques were utilized. In Malaysia, a random sample of 49 respondents from two public universities in Sarawak, Malaysia was chosen out of which 6 respondents were purposively selected and interviewed. The Wilcoxon Signed Rank Test showed that there was a statistically significant difference in the pre-test and the post-test for the control group, Z=-3.978, p=0.001 as well as for the experimental group, Z=-4.275, p=0.001. In comparing the gains between the experimental and the control groups, however, the test indicated insignificant difference in the gain scores, Z=-0.142, p=0.887. In Singapore, 29 respondents were selected on a voluntary basis from one of the public universities. Eight respondents were purposively selected and interviewed. Paired t- Test showed that there was significant gain in the pre and post-tests (t=7.678,p=0.001). For both Malaysia and Singapore, a more detailed analysis with programme of study and Cumulative Grade Point Average (CGPA) as independent variables

Cationic Sites on Granzyme B Contribute to Cytotoxicity by Promoting Its Uptake into Target Cells

Granzyme B (GrB) is a key effector of cytotoxic lymphocyte-mediated cell death. It is delivered to target cells bound to the proteoglycan serglycin, but how it crosses the plasma membrane and accesses substrates in the cytoplasm is poorly understood. Here we identify two cationic sequences on GrB that facilitate its binding and uptake. Mutation of cationic sequence 1 (cs1) prevents accumulation of GrB in a distinctive intracellular compartment and reduces cytotoxicity 20-fold. Mutation of cs2 reduces accumulation in this intracellular compartment and cytotoxicity two- to threefold. We also show that GrB-mediated cytotoxicity is abrogated by heparin and that target cells deficient in cell surface sulfate or glycosaminoglycans resist GrB. However, heparin does not completely prevent GrB internalization and chondroitin 4-sulfate does not inhibit cytotoxicity, suggesting that glycosaminoglycans are not essential GrB receptors. We propose that GrB enters cells by nonselective adsorptive pinocytosis, exchanging from chondroitin sulfate on serglycin to anionic components of the cell surface. In this electrostatic “exchange-adsorption” model, cs1 and cs2 participate in binding of GrB to the cell surface, thereby promoting its uptake and eventual release into the cytoplasm

Effectiveness Of Stestmap On Facilitating Significance Test Selection

In the hypothesis testing process, one of the difficult steps was in determining the appropriate significance test 10 use. Any misstep in the selection process could cause the users to come to the wrong conclusion. This study aimed to evaluate the effectiveness of STestMAP to help in the selection ofthe significance test. The study was quantitative in nature. Three instruments, which consisted of prior knowledge test, pre-test and post-test were adopted and administered. Data collection was carried out through paper-and-pencil tests. Quantitative (descriptive and inferential analysis) data analysis techniques were utilized. In Malaysia, a random sample of49 respondents from two public universities in Sarawak was chosen. The Wilcoxon Signed Rank Test showed that there was a statistically significant difference in pre-test and post-test for the control group, Z=-3.978, p=0.001 as well asfor the experimental group, Z=-4.275, p=0.001. In comparing the scores between the experimental and control group, however, the test indicated insignificant difference, Z=-0.142, p=0.887.111 Singapore, 29 respondents were selected on a voluntary basis from one of the public universities. Paired t-Test showed that there was a significant gain in the pre and post-tests (t= 7.678, p=0.001). For both Malaysia and Singapore, the analysis on the Cumulative Grade Point Average (CGPA) revealed statistical significant differences for certain group comparisons