Why Doesn't the Creed Read "Always Be Critical"? An Examination of a Liberal Curriculum

Using ethnographic data collected in a second grade classroom over the course of a school year, this paper describes the ways in which one school's discourse of liberalism is deleteriously deployed. We view the school's discipline creed as emblematic of the school's liberal curriculum, and interrogate the effects on four African American boys in the classroom when the school enacts this creed. Despite the agency that these boys obviously had, they were unable to control the ways in which they were placed at a structural disadvantage and manipulated by a system far more powerful than they were. The results were that these four boys suffered. Not only did the intended liberal curriculum fail to be translated fully into the enacted curriculum, the liberal underpinnings of this curriculum precluded teachers and students from taking any critical stance.     

GROWTH AND DEVELOPMENT OF THE MALE GAMETOPHYTE OF GINKGO BILOBA WITHIN THE OVULE (IN VIVO)

The mature male gametophyte of Ginkgo biloba can be divided into two regions: a large saccate structure that is suspended within the fertilization chamber above the archegonia, and a pervasive, highly branched haustorial system that ramifies through the intercellular air spaces of the apex of the nucellus. This morphology appears to differ in many ways from the simpler more typical male gametophytes of most other groups of seed plants. Growth and development of the male gametophyte of Ginkgo biloba were studied using computer reconstruction techniques to generate images of the gametophyte from data derived from serial sections through the ovule. These investigations reveal that morphological development of the male gametophyte of Ginkgo biloba is divided into three distinct phases: 1) Germination, characterized by an initial brief period of diffuse growth. This phenomenon has not been described for any other seed plant male gametophyte; 2) Initiation of tip growth and the formation of a tubular body, as typifies all seed plant male gametophytes. In Ginkgo, this is accompanied by a high degree of branching, giving rise to an extensively branched haustorial system; 3) Late swelling of the proximal unbranched portion of the gametophyte resulting in formation of the saccate structure that is characteristic of the mature gametophyte. This process appears to be very similar to late development in cycad male gametophytes. Thus, despite the seemingly anomalous morphology of the mature male gametophyte of Ginkgo biloba, specific patterns of growth and development are in many ways similar to growth processes expressed by the male gametophytes of some or all major groups of seed plants.     

Parasitoid behaviour: predicting field from laboratory

Abstract.  1. Most of what is known about parasitoid behaviour comes from laboratory observations: field quantitative observations on searching parasitoids are extremely difficult to do and are rare. The basic components of Aphytis melinus 's response to California red scale ( Aonidiella aurantii ) were studied in the laboratory: encounter, rejection, drumming, probing, oviposition, and host-feeding. It was then asked whether these observations provided a reliable guide to behaviour in the field in a situation that was very different from the laboratory.
2. Field observations were carried out on bark on the trunk and interior branches of trees where live scale density is extremely high in patches, dead scale make up 90% of all scale, and could be expected to interfere with Aphytis search.
3. The laboratory observations predicted well the time taken in the field for each basic event (drumming or probing) and average times spent on a scale. Also well predicted were the distributions of times spent on drumming, probing, and total time on a scale. Rejection rates were much higher in the field. Thus, the laboratory studies predicted foraging behaviour in the field with variable success; potential explanations for observed mismatch between laboratory and field and its possible larger implications are discussed.     

Genetic research with nonhuman primates: serving the needs of mankind Symposium summary and future prospects

The wide array of papers delivered at this symposium, ranging from population genetics to molecular genetics, is convincing evidence that genetic research with nonhuman primates is in full bloom. In fact, progress has been quite remarkable considering that a significant number of pedigreed colonies of nonhuman primates have been available for less than 25 years, which is hardly enough time to raise 3 generations of chimpanzees, 5 generations of baboons or 6 generations of rhesus monkeys. Were it not for these pedigreed colonies, we would not have been privileged to have this assemblage of papers on behavior, social structure, predisposition to disease and management of breeding colonies. It is indeed exciting that preliminary evidence has been obtained for major genes that play a role in susceptibility to dyslipoproteinemias in baboons, and that monoclonal antibodies and DNA markers are helping us to understand cholesterol metabolism. And thanks to computers, we can now rank animals in a colony in terms of their useful genotypes as well as their productivity. One can not help but be impressed with the commonality of humans and nonhuman primates at the structural and functional levels. For example, the major histocompatibility systems and the maternal-fetal relationships are very similar. We heard that this similarity is even more striking at the chromosomal, biochemical and DNA levels. A provocative question yet to be answered is, “what accounts for the obvious differences between humans and nonhuman primates in view of these incredible similarities?” In light of these advances, this symposium was at the cutting edge of primate genetics and the papers published in this issue of Genetica are certain to be hallmarks in the literature.     

Formation of Metallogenium-like structures by a manganese-oxiding fungus

Structures resembling Metallogenium spp. were observed in agar and in liquid cultures of a Mn-oxidizing basidiomycetous fungus only when Mn²⁺ was oxidized. Fungal viability was necessary for formation of the structures; Mn²⁺ concentration and the presence or absence of agar in the medium were important factors determining their morphology. Slide cultures revealed no identifiable cells in any stage of development. Fluorescent dyes that stained nucleic acids and polysaccharides in the fungal hyphae did not stain the Metallogenium-like structures. Likewise, Rhodamine 123, a fluorescent probe for membrane potential, stained fungal mitochondria, but did not stain the structures. Thin sections through the structures showed no biological membranes or other cellular features. Only the characteristic ultrastructure of biological Mn oxides were observed in serial thin sections. In agar, unfixed structures disappeared permanently during reduction of Mn oxides with hydroxylamine. Glutaraldehyde fixation stabilized these structures. Fixed structures lost most of their original phase density during reduction with hydroxylamine, but continuous microscopic observations showed that their phase density could be restored by staining with Coomassie blue. Structures that formed in liquid medium did not require stabilization with glutaraldehyde during reduction of Mn oxides. They, too, lost their original phase density during reduction with hydroxylamine; phase density could be restored by staining with cationic colloidal iron or Coomassie blue. The results suggest that the Metallogenium-like structures were formed as a result of Mn oxidation associated with exopolymers produced by the fungus.Non-standard abbreviations HEPES (N-hydroxyethylpiperazine-N-2-ethane sulfonic acid) - DAPI (4,6-diamidino-2-phenylindole) - PIPES (piperazine-N,N-bis[2-ethane sulfonic acid])     

Behavior of captive-raised rattlesnakes (Crotalus enyo) as a function of rearing conditions

Two litters of rattlesnakes (Crotalus enyo; n = 6 per litter) were raised in large cages and small plastic boxes, respectively. No significant differences in exploration of a novel environment were observed between the litters, or between either of them and a group of wild-caught C. enyo, suggesting that the common practice of rearing baby snakes in small cages has no debilitating consequences on these measures. In the absence of differences between the litters, the two samples were pooled and additional analyses revealed the existence of reliable individual variation. Experiment 2 compared the two litters and the wild-caught snakes on measures of prey-directed behavior. The two captive-reared litters did not differ, but both exhibited lower levels of strike-induced chemosensory searching than did wild-caught snakes.