Asprich: A novel aspartic acid-rich protein family from the prismatic shell matrix of the bivalve Atrina rigida

Almost all mineralized tissues contain proteins that are unusually acidic. As they are also often intimately associated with the mineral phase, they are thought to fulfill important functions in controlling mineral formation. Relatively little is known about these important proteins, because their acidic nature causes technical difficulties during purification and characterization procedures. Much effort has been made to overcome these problems, particularly in the study of mollusk-shell formation. To date about 16 proteins from mollusk-shell organic matrices have been sequenced, but only two are unusually rich in aspartic and glutamic acids. Here we screened a cDNA library made from the mRNA of the shell-forming cells of a bivalve, Atrina rigida, using probes for short Asp-containing repeat sequences, and identified ten different proteins. Using more specific probes designed from one subgroup of conserved sequences, we obtained the full sequences of a family of seven aspartic acid-rich proteins, which we named "Asprich"; a subfamily of the unusually acidic shell-matrix proteins. Polyclonal antibodies raised against a synthetic peptide of the conserved acidic1 domain of these proteins reacted specifically with the matrix components of the calcitic prismatic layer, but not with those of the aragonitic nacreous layer. Thus the Asprich proteins are constituents of the prismatic layer shell matrix. We can identify different domains within these sequences, including a signal peptide characteristic of proteins destined for extracellular secretion, a conserved domain rich in aspartic acid that contains a sequence very similar to the calcium-binding domain of Calsequestrin, and another domain rich in aspartic acid, that varies between the seven sequences. We also identified a domain with DEAD repeats that may have Mg-binding capabilities. Although we do not know, as yet, the function of these proteins, their generally conserved sequences do indicate that they might well fulfill basic functions in shell formation.     

Sex differences in interaction and achievement in cooperative small groups.

44 male and female 7th–8th graders in 2 mathematics classes worked for 2 wks in male- or female-majority groups or groups with equal numbers of males and females. Same-sex and cross-sex interactions were analyzed for giving, requesting, and receiving explanations and procedural information. Achievement and interaction results were related to the ratio of females to males in a group. Females and males showed equal achievement and similar interaction patterns in groups with equal numbers of females and males. In majority-female groups, females directed most of their interaction to males and showed lower achievement than males. In majority-male groups, males tended to ignore females and showed somewhat higher achievement than did females. Explanations for these results are considered in terms of status characteristics and expectations states, and consequences for group composition in the classroom are discussed. (34 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Infection and anemia in Canadian aboriginal infants.

The prevalence of anemia in Aboriginal children is high, but, given the high burden of infection in these children, the extent to which anemia is due to iron deficiency and/or infection is unclear. To determine the contribution of iron deficiency to anemia, we screened 144 Aboriginal infants (70 boys, 74 girls) who were free from infection. The prevalence of anemia (hemoglobin <105 g/L) was 18.8%; caregivers reported that 53.5% of infants had had an infection in the two weeks before screening. Anemic infants were more likely than non-anemic infants to have had an infection before screening (74.1% versus 48.7%, p = 0.02), and anemic infants had a higher prevalence of iron deficiency revealed by low serum iron concentrations (<7 micromol/L) (73.7% versus 38.3%, p <0.01). Iron deficiency measured using serum ferritin concentration tended to be less marked in infants who had had an infection (13% versus 30.3%, p = 0.06); this is probably because serum ferritin is a positive acute-phase protein. This study indicates the difficulty of isolating the contribution of infection to anemia from the separate effects of dietary iron deficiency.