The transition to high school for academically promising, urban, low-income African American youth.

In nine urban Ohio school systems, low-income minority students identified as academically promising in sixth grade are eligible to participate in an intervention program. In the present study, twenty-two African American students in the program were asked to provide their perceptions of the transition to ninth grade. Specifically, the role of motivating factors, peers, school, teachers, parents, and neighborhood were examined. These students faced similar stressors, yet some were more able to achieve academic success. Results highlight the salience of mothers, the challenges of the ninth-grade curriculum, and adjustment to a bigger, more complex school environment for high and low performers. The implications for improving cooperation between school and family are discussed.

What does it take to have a positive impact on minority students' college retention?

This paper describes the Young Scholars Program (YSP), which seeks to expand the pool of African American and other underrepresented minority youth who aspire to attend college, and to help them meet entrance requirements and successfully obtain a college degree. Quarter-by-quarter data for the first two groups of YSP students entering The Ohio State University were promising. Their retention rates approximated university averages, while comparison groups showed lower levels of retention. It was concluded that the many facets of the Young Scholars Program, as well as the students' positive reputation among family members, peers, and teachers, produced strong motivation, ability, and determination to succeed.

Site-directed mutagenesis of the yeast V-ATPase A subunit.

To investigate the function of residues at the catalytic nucleotide binding site of the V-ATPase, we have carried out site-directed mutagenesis of the VMA1 gene encoding the A subunit of the V-ATPase in yeast. Of the three cysteine residues that are conserved in all A subunits sequenced thus far, two (Cys284 and Cys539) appear essential for correct folding or stability of the A subunit. Mutation of the third cysteine (Cys261), located in the glycine-rich loop, to valine, generated an enzyme that was fully active but resistant to inhibition by N-ethylmalemide, 7-chloro-4-nitrobenz-2-oxa-1,3-diazole, and oxidation. To test the role of disulfide bond formation in regulation of vacuolar acidification in vivo, we have also determined the effect of the C261V mutant on targeting and processing of the soluble vacuolar protein carboxypeptidase Y. No difference in carboxypeptidase Y targeting or processing is observed between the wild type and C261V mutant, suggesting that disulfide bond formation in the V-ATPase A subunit is not essential for controlling vacuolar acidification in the Golgi. In addition, fluid phase endocytosis of Lucifer Yellow, quinacrine staining of acidic intracellular compartments and cell growth are indistinguishable in the C261V and wild type cells. Mutation of G250D in the glycine-rich loop also resulted in destabilization of the A subunit, whereas mutation of the lysine residue in this region (K263Q) gave a V-ATPase complex which showed normal levels of A subunit on the vacuolar membrane but was unstable to detergent solubilization and isolation and was totally lacking in V-ATPase activity. By contrast, mutation of the acidic residue, which has been postulated to play a direct catalytic role in the homologous F-ATPases (E286Q), had no effect on stability or assembly of the V-ATPase complex, but also led to complete loss of V-ATPase activity. The E286Q mutant showed labeling by 2-azido-[32P]ATP that was approximately 60% of that observed for wild type, suggesting that mutation of this glutamic acid residue affected primarily ATP hydrolysis rather than nucleotide binding.

Site-directed mutagenesis of the yeast V-ATPase B subunit (Vma2p).

The B subunit of the vacuolar (H+)-ATPase (V-ATPase) has previously been shown to participate in nucleotide binding and to possess significant sequence homology with the alpha subunit of the mitochondrial F-ATPase, which forms the major portion of the noncatalytic nucleotide binding sites and contributes several residues to the catalytic sites of this complex. Based upon the recent x-ray structure of the mitochondrial F1 ATPase (Abrahams, J.P., Leslie, A.G., Lutter, R., and Walker, J.E. (1994) Nature 370,621-628), site-directed mutagenesis of the yeast VMA2 gene has been carried out in a strain containing a deletion of this gene. VMA2 encodes the yeast V-ATPase B subunit (Vma2p). Mutations at two residues postulated to be contributed by Vma2p to the catalytic site (R381S and Y352S) resulted in a complete loss of ATPase activity and proton transport, with the former having a partial effect on V-ATPase assembly. Interestingly, substitution of Phe for Tyr-352 had only minor effects on activity (15-30% inhibition), suggesting the requirement for an aromatic ring at this position. Alteration of Tyr-370, which is postulated to be near the adenine binding pocket at the noncatalytic sites, to Arg, Phe, or Ser caused a 30-50% inhibition of proton transport and ATPase activity, suggesting that an aromatic ring is not essential at this position. Finally, mutagenesis of residues in the region corresponding to the P-loop of the alpha subunit (H180K, H180G, H180D, N181V) also inhibited proton transport and ATPase activity by approximately 30-50%. None of the mutations in either the putative adenine binding pocket nor the P-loop region had any effect on the ability of Vma2p to correctly fold nor on the V-ATPase to correctly assemble. The significance of these results for the structure and function of the nucleotide binding sites on the B subunit is discussed.

Rat gastric H,K-ATPase beta-subunit gene: intron/exon organization, identification of multiple transcription initiation sites, and analysis of the 5'-flanking region.

A rat genomic library was screened using a gastric H,K-ATPase beta-subunit cDNA probe, and two clones were identified. Restriction endonuclease mapping and Southern hybridization analyses indicated that each of these clones contains the entire H,K-ATPase beta-subunit gene. The nucleotide sequence was determined for the 8.75-kb transcription unit and 2.2 kb of the 5'-flanking region. The gene consists of seven exons and shows a high degree of similarity to the Na,K-ATPase beta 1-subunit gene. Primer extension and S1 nuclease protection analyses identified a major transcription initiation site 23 bases upstream of the translation start site and several minor transcription initiation sites located further upstream. The 5'-flanking region of the gene has two potential TATA sequences, each located 25-30 bases upstream of a transcription initiation site, and a number of potential promoter and regulatory elements. In addition, the 5'-flanking region contains nucleotide sequences that may regulate transcription through the formation of unusual DNA structures. These include a sequence that may form a triple helix and an adjacent sequence with the potential to form Z-DNA.

Structure of the human gastric H,K-ATPase gene and comparison of the 5'-flanking sequences of the human and rat genes.

We have isolated and analyzed the genes encoding the human and rat gastric H,K-ATPase catalytic subunits. The complete sequence of the human gene, including 2.2 kb of 5'-flanking sequence, and the 5' end of the rat gene, including exons 1-4 and 2.5 kb of 5'-flanking sequence, have been determined. The human gene contains 22 exons. Its intron-exon organization is identical to that of the Na,K-ATPase gene, except that exon 6 corresponds to a fusion of exons 6 and 7 of the Na,K-ATPase gene. The transcription initiation sites of both the human and rat genes were determined by primer extension and S1 nuclease protection analyses. Comparison of the 5'-flanking regions of the human and rat genes revealed three extended regions of high sequence similarity, one of which includes a potential TATA box and other basic promoter elements beginning about 30 nucleotides upstream of the transcription start site. Other conserved sequences, including possible response elements for Ca2+ and cAMP, which are known intracellular mediators of acid secretion, are located up to 2 kb 5' to the transcription initiation site.

cDNA cloning and tissue distribution of mRNAs for two proteins that are related to the band 3 Cl-/HCO3- exchanger.

Complementary DNAs encoding two proteins that are related to the Band 3 Cl-/HCO3- exchanger, designated B3RP2 and B3RP3, have been isolated from rat stomach, brain, and kidney libraries. B3RP2 is 1234 amino acids in length and has an Mr of 136,644. B3RP3 is 1227 amino acids in length and has an Mr of 135,405. B3RP2 and B3RP3 exhibit 52 and 50% amino acid identity to Band 3, respectively, and 56% identity to each other. The N-terminal cytoplasmic regions of B3RP2 and B3RP3, which span about 700 amino acids, are more extensive than that of Band 3. The C-terminal hydrophobic regions of the three proteins exhibit a high degree of amino acid identity (64-69%) and have very similar hydropathy profiles, suggesting that they have the same transmembrane organization. The tissue distribution of mRNAs encoding B3RP2, B3RP3, and the Band 3 Cl-/HCO3- exchanger were examined by Northern blot hybridization using poly(A)+ RNAs from a broad range of muscle and non-muscle tissues and from sections of the gastrointestinal tract. B3RP2 mRNAs are expressed in all tissues examined. The highest levels, which include at least three different transcripts, occur in stomach. B3RP3 mRNAs, which also consist of several different transcripts, have a more limited tissue distribution. The highest levels occur in heart, and in gastrointestinal sections the highest levels are in the forestomach. Band 3 mRNAs were observed in many tissues but high levels of expression occurred only in spleen and kidney. Five Band 3 transcripts, ranging in size from 3.6 to 4.9 kilobases, were detected, including three that are expressed in heart.

The impact of high school on social development.

In reviewing the literature on the social impact of high school, six themes were identified: (1) students perceive strong norms for conformity to school rules, (2) the emphasis on conformity and control influences the quality of student/teacher relations which tend to be role bound and inflexible, (3) paths to social status continue to emphasize athletic competence, (4) peer group identification has an impact on social relations within the larger community as well as in the school setting, (5) powerlessness is felt as a result of the authoritarian approach to decision making, and (6) the overall high school environment does not enhance students' beliefs in the Bill of Rights. It was concluded that high school students have limited opportunities for flexible self-definition. As a result of the way they are treated by authority figures and the strong pressures toward conformity, many adolescents fail to learn the extent of their rights or effective strategies for the exercise of power.

A quantitative fluorometric assay for the measurement of antibody to Pasteurella haemolytica in cattle.

A rapid, simple fluorometric method is described for measuring antibody to Pasteurella haemolytica in sera of cattle. Various antigen preparations were compared for the test including live, formalin-killed and phenol-killed P. haemolytica. A preparation composed of formalin-killed organisms from a 22 hour culture gave consistent results and was used in the studies. The test was reproduciable with percent coefficients of variation for fluorescent signal unit values on ten or more replicate samples ranging from 5.7 to 28.0. Sera from calves vaccinated by aerosol exposure to live P. haemolytica had up to a five-fold increase in antibody titer as measured by the flurometric method test during a 21 day period. Fluorometric method titers were comparable to those obtained by the indirect bacterial agglutination test. There was no seroconversion to P. haemolytica in calves vaccinated by aerosol exposure of P. multocida. The major advantages of the fluorometric method test over conventional methods are that the assay does not require serial dilutions of serum samples and thus limits time and effort to determine antibody titers.

Demonstration of age-dependent capsular material on Pasteurella haemolytica serotype 1.

Extracellular capsular material was demonstrated on early log-phase cells of Pasteurella haemolytica serotype 1 by the fluorescent-antibody and several capsular staining techniques. The presence of this material was shown to be age dependent. Wide capsules were demonstrable on cells from 2- to 12-h cultures, whereas cells from 16- to 22-h cultures had very little cell-associated capsular material. The Maneval technique most clearly demonstrated the presence of capsules on cells from young (6-h) cultures when compared with other capsule staining techniques.

Distribution of Pasteurella haemolytica and Pasteurella multocida in the bovine lung following vaccination and challenge exposure as an indicator of lung resistance.

Experimental calves were vaccinated with virulent strains of Pasteurella haemolytica or Pasteurella multocida or with phosphate-buffered saline solution either by an aerosol method or by subcutaneous injection. Calves were subsequently challenge exposed by intrapulmonic inoculation of the homologous virulent Pasteurella species. Sections obtained from the resulting pulmonic lesion were stained, using a fluorescent antibody technique, to determine relative number, location, and integrity of the challenge organism. The resistance of the calf to challenge exposure, as determined by other factors, was compared with the capacity of the components of the lung to engulf or destroy pasteurellae. Calves vaccinated with an aerosol of the bacterium were most resistant to challenge exposure; most bacteria were engulfed or degraded by the phagocytic cells. Vaccination by subcutaneous injection was less effective in inducing resistance. Tissue sections from these calves contained many more extracellular intact bacteria and fewer intracellular intact or degraded bacteria than were seen in the sections of calves vaccinated by the aerosol method. The control calves were the least resistant; bacteria seen in tissue sections from these calves were numerous, predominantly extracellular, and intact. A group of nonvaccinated calves experimentally inoculated with infectious bovine rhinotracheitis virus 5 days before intrapulmonic challenge exposure with P haemolytica developed severe pulmonic lesions. The lesions were larger and more invasive and contained many more extracellular bacteria than did the lungs of calves in control groups. As in other nonvaccinated calves, there were few intracellular bacteria; however, unlike in other calves, the extracellular bacteria were seen in large numbers, particularly in alveolar lumens.

The concept of identity: research and theory.

The concept of identity is one of the few themes of psychosocial theory that has been researched directly. The dichotomy between identity achievement and role diffusion can be more accurately understood as two potential statuses among a number of resolutions to the identity crisis. Identity status appears to be related to significant childrearing experiences, particularly to dimensions of warmth, limit setting, values of autonomy, and achievement orientation. The pattern of identity achievement is different for males and females. Successful achievement of identity reflects different parental child-rearing practices for males and females.