Gender and racial favouritism in black and white preschool girls.

The authors examined gender and racial preferential behaviour in 108 3- and 5-year-old Black and White girls. Children set up a birthday party for dolls that differed in gender and racial physical characteristics. Whereas White girls showed favouritism towards the doll most closely resembling themselves in both gender and race, Black girls showed most favouritism towards the White girl doll. Black girls were more likely to show preference based on gender rather than race, whereas White girls were equally likely to show race- or gender-based favouritism. Among White 5-year-olds, greater prior interaction with Blacks was positively associated with race-related favouritism (i.e., secondary preference to the White boy doll rather than the Black girl doll). Interracial contact was unrelated to racial favouritism among the other three groups. Results demonstrate the salience of gender identity during the preschool years, and indicate that majority/minority status and intergroup contact shape the development of collective identity and social behaviour.

Surveillance for antibodies to Leishmania spp. in dogs from Sri Lanka.

The global distribution of leishmaniasis is rapidly expanding into new geographic regions. Dogs are the primary reservoir hosts for human visceral leishmaniasis caused by infection with Leishmania infantum. Natural infections with other Leishmania spp. can occur in dogs, but their role as reservoir hosts for other species of Leishmania is uncertain. Leishmania donovani is traditionally considered a visceralizing anthroponotic species; however, cutaneous leishmaniasis caused by L. donovani has been reported in Sri Lanka. In the present study, sera from 114 dogs in Sri Lanka were examined for antibodies to visceralizing Leishmania spp. Sera were tested by the canine immunochromatographic strip assays based on recombinant K39 antigen. Anti-Leishmania spp. antibodies were detectable in 1 of 114 (0.9%) dogs from Sri Lanka. Nonetheless, serological evidence suggests that leishmaniasis may be an emerging zoonosis in Sri Lanka.

Children's theories of intelligence: beliefs, goals, and motivation in the elementary years.

The authors tested a developmental model of children's theories about intelligence in kindergarten, second grade, and fourth grade children by using paper-and-pencil maze tasks. Older children were more likely than younger children to espouse learning goals (e.g., that they preferred difficult mazes to improve their skill), and less likely to espouse performance goals (e.g., that they preferred easy mazes to be successful). Children in all 3 age groups reported stronger beliefs in the malleability of intelligence than the stability of intelligence. In general, the results supported the authors' hypotheses about developmental change in children's theory-like conceptions of intelligence: Beliefs, goals, and motivation were related in expected ways for second and fourth graders more than for kindergartners. The authors discussed contextual influences on children's beliefs and the development of children's conceptualizations of intelligence.

IFG, a gypsy-like retrotransposon in Pinus (Pinaceae), has an extensive history in pines.

A 1 kb EcoRI restriction fragment cloned from a band visible in an agarose gel of Pinus lambertiana (sugar pine) genomic DNA is present in both subgenera of Pinus with at least 10(4) copies/genome. A full-length copy of this repeated element recovered from a P. radiata (Monterey pine) genomic DNA library was found to possess all of the sequence features associated with gypsy-like retrotransposons. This report describes the biology and history of the IFG (Institute of Forest Genetics) family of retrotransposons. The characterized IFG7 is 5937 bp long. Immediately interior to its 5' and 3' long terminal repeats are sequences consistent with primer binding sites for reverse transcription of the RNA genome. Presumptive gene products associated with retrotransposition appear to be coded in a single reading frame and are in the same order as the gypsy-like retrotransposons and retroviruses. The 1.0 kb EcoRI fragment of IFG elements codes for the 3' half of IFG's reverse transcriptase and the entire RNase H domain. Southern blot analysis suggests IFG was present in Pinaceae before its division into its modern genera. Sequence analysis of IFG 1.0 kb RI fragments and southern analysis also suggest that IFG continued to evolve in Pinus with restriction fragment length polymorphism (RFLP) subfamilies appearing early in the history of each subgenus often correlating with subdivisions of Pinus. Features shared with other plant retrotransposons are also discussed.

Lipid transfer protein genes of loblolly pine are members of a complex gene family.

A loblolly pine (Pinus taeda L.) cDNA with properties of a nonspecific lipid transfer protein (nsltp) is reported. In contrast to simple family structures reported for a variety of angiosperm nsltp genes, the putative pine nsltp gene is a member of a complex family.

Expression of cab Genes in Douglas-Fir Is Not Strongly Regulated by Light.

Dark-grown Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) seedlings had approximately 30% of the major polypeptide of the light-harvesting chlorophyll a/b binding protein, 30% of cab mRNA, 54% of psbA mRNA, and 14% of total chlorophyll, in comparison with amounts in light-grown seedlings. Seedlings entrained under a 24-hour photoperiod of light and dark showed small diurnal fluctuations in cab and psbA mRNA levels and, when transferred to continuous conditions, no circadian rhythms in mRNA levels were apparent. These results suggest that regulation of cab gene expression in Douglas-fir differs from regulation in angiosperms, because in the latter, both light and circadian factors strongly influence the expression of cab genes.

Molecular evolution of the zinc-containing long-chain alcohol dehydrogenase genes.

Phylogenetic relationships and rates of nucleotide substitution were studied for alcohol dehydrogenase (ADH) genes by using DNA sequences from mammals and plants. Mammalian ADH sequences include the three class I genes and a class II gene from humans and one gene each from baboon, rat, and mouse. Plant sequences include two ADH genes each from maize and rice, three genes from barley, and one gene each from wheat and two dicots, Arabidopsis and pea. Phylogenetic trees show that relationships among ADH genes are generally consistent with taxonomic relationships: mammalian and plant ADH genes are classified into two distinct groups; primate class I genes are clustered; and two dicot sequences are clustered separately from monocot sequences. Accelerated evolution has been detected among the duplicated ADH genes in plants, in which synonymous substitutions occurred more often within the coenzyme-binding domain than within the catalytic domains.

Fractionation and characterization of human small nuclear ribonucleoproteins containing U1 and U2 RNAs.

Human small nuclear ribonucleoproteins (snRNPs) containing U1 and U2 snRNAs have been isolated from cultured cells by nonimmunological methods. The U1 snRNP population remained immunoprecipitable by systemic lupus erythematosis anti-RNP and anti-Sm antibodies throughout fractionation and contained polypeptides of molecular weights corresponding to those defined as U1 snRNP polypeptides by immunoprecipitation of crude extracts. The purified assemblies contained U1 RNA and nine snRNP polypeptides of molecular weights 67,000 (P67), 30,000 (P30), 23,000 (P23), 21,500 (P22), 17,500 (P18), 12,300 (P12), 10,200 (P10), 9,100 (P9), and 8,500 (P8). P67, P30, and P18 were unique to U1 snRNPs. The U2 snRNP population remained immunoprecipitable by the systemic lupus erythematosis anti-Sm antibody throughout fractionation. The purified U2 assemblies contained six polypeptides of molecular weights corresponding to those defined by immunoprecipitation to be common to U1 and U2 snRNPs including P23, P22, P12, P10, P9, and P8. In addition, U2 snRNPs contained a unique polypeptide of 27,000 Da.

Human U1 and U2 small nuclear ribonucleoproteins contain common and unique polypeptides.

Immunoprecipitation of human small nuclear ribonucleoproteins (snRNPs) containing the small nuclear RNAs U1, U2, U4, U5, and U6 with two antibodies produced in certain patients suffering from systemic lupus erythematosus was used to identify the polypeptides present on human U1 and U2 snRNPs. U1 and U2 snRNPs contain both common and unique polypeptides; visualization of the differences was possible through the use of non-methionine protein labeling and partial fractionation of snRNP populations. To facilitate comparisons with results from other laboratories, we have designated the snRNP polypeptides by their molecular weights. Four small polypeptides, P8, P9, P10, and P12, of 8,000 to 12,000 daltons, are each present in equal amounts on both U1 and U2 snRNPs. U1 snRNPs also contain a unique 30,000-dalton polypeptide, P30, whereas U2 snRNPs contain a unique 27,000-dalton, methionine-deficient polypeptide, P27. A closely migrating pair of polypeptides, P23 and P22, of 23,000 and 21,500 daltons, respectively, is present on both snRNPs; U2 snRNPs are enriched in the former, and U1 snRNPs are enriched in the latter.