Hair morphology and systematics ofPhysalis (Solanaceae)

Hair morphology was exammed on developing seedlings and mature plants of ten species from five of seven series inPhysalis. The taxonomic importance of hair development and the distribution of hair types then was evaluated with respect to other comparative data. Two classes of hair types were observed, as found in earlier investigations ofSolanum andRhododendron. The first hair class comprises a sequence from unbranched hairs to dendroid-stelliform hairs. Hairs of this class show considerable variability among taxa in size, presence or absence of glandular tips, and presence and degree of branching, and so were useful in making taxonomic comparisons. The second hair class consists of short hairs, each tipped with a multicellular gland. This second hair class was not useful taxonomically because of its lack of variability in morphology and its often rare occurrence on a plant. The taxa studied exhibit distinctive trichome features which serve to distinguish series and, in some cases together with other data, provided new insight into previously enigmatic species relationships.     

Immunomodulating effects in vitro of interleukin-2 and interferon-gamma on human blood and bone marrow mononuclear cells

Mononuclear cells (MNC) derived from peripheral blood (PBMNC) of 23 normal donors and 4 AIDS patients, and from bone marrow (BMMNC) of 15 normal donors were incubated at 37 degrees C in culture medium alone or in the presence of either natural or recombinant human interleukin-2 (IL-2) or recombinant human interferon-gamma (IFN-gamma; 1-1,000 U/ml). The cultured cells were washed on days 1, 4 or 7 and tested for various immune functions in vitro and for cell surface phenotype. IL-2, but not IFN-gamma, was found mitogenic for both PBMNC and BMMNC. The natural killer (NK) activity of both PBMNC and BMMNC was the only function tested that was markedly augmented (over 100-fold compared to medium control) by both lymphokines. Pretreatment of PBMNC with IL-2 at greater than or equal to 10 U/ml profoundly suppressed (up to 90%) various functions, such as mitogenic responses (phytohemmagglutinin, concanavalin A, pokeweed mitogen), allogeneic mixed leukocyte reaction, antibody production and T cell colony formation in agar. In contrast, some BMMNC functions were elevated at low doses of IL-2 and IFN-gamma, and significant suppression of BMMNC was seen only with high doses of IL-2 (greater than or equal to 100 U/ml) and IFN-gamma (1,000 U/ml). IL-2 was by far more effective than IFN-gamma in both the amplification of NK activity and the suppression of most of the other functions. IL-2, but not IFN-gamma, was found to activate/induce suppressor cells and increased the proportion of Leu-2+ (CD8) cells in PBMNC; the suppressive effect was time- and dose-dependent. The IL-2-induced suppression could be diminished by inclusion of anti-IL-2 antibody during the pretreatment phase. Similar suppressive effects were noted in PBMNC from AIDS patients. These findings suggest that: (a) high-dose IL-2 may elicit immunosuppression which can be mediated by nondiscriminative highly cytotoxic cells (i.e. lymphokine-activated killer cells) and/or by noncytotoxic, nonspecific suppressor cells, and (b) that PBMNC respond differently to the lymphokines than do BMMNC.     

Control of myogenesis in the mouse myogenic C2 cell line by medium composition and by insulin: Characterization of permissive and inducible C2 myoblasts

Using subcloning and manipulations of culture conditions we have isolated from the mouse myogenic cell line C2 a variant cell line that we named inducible. Unlike the progenitor cells that are referred to as permissive, inducible myoblasts differentiate poorly in Dulbecco modified Eagle medium plus fetal calf serum (FCS) and require the presence of insulin at a high concentration (1.6 10(-6) M) or insulin-like growth factor I (IGFI) at a lower concentration (2.5 10(-8) M) to differentiate. Permissive and inducible myoblasts fail to differentiate when grown in MCDB202 medium plus 20% FCS, even after a prolonged arrest in G1 phase. This shows that an arrest in G1 is in itself insufficient to trigger terminal differentiation. Both cell types also exhibit distinct patterns of accumulation of muscle mRNAs corresponding to sarcomeric actins and myosin light chain MLC1A. The possibility that these two cell lines might represent two different stages of the progression of myoblasts toward terminal differentiation is discussed.     

Guidelines for the Control of Human Immunodeficiency Virus Infection in Adolescents

Although adolescents account for only 0.4% of reported cases of the acquired immunodeficiency syndrome (AIDS) in the United States, they are sexually active and, therefore, at risk of acquiring human immunodeficiency virus (HIV) infection. To address issues of HIV control in adolescents, we developed guidelines that emphasize education and medical care and deemphasize antibody testing. For adolescents known to be infected with HIV, we recommend no restrictions on access to educational or treatment programs except when their health providers recommend such restrictions to protect them from exposure to opportunistic infections. For adolescents of unknown antibody status with a possible previous exposure to HIV, we recommend that as long as the incidence of HIV infection and clinical AIDS remains low, there should be no restrictions on residential placements and no routine antibody testing.     

Copper absorption in young men fed adequate and low zinc diets

Copper absorption was measured at two levels of dietary zinc in six healthy young men who were confined to a metabolic unit for a 75 d study of zinc utilization. A diet of conventional foods was fed, providing either 16.5 or 5.5 mg zinc and 1.3 mg copper daily. Copper absorption was determined by feeding⁶⁵Cu, a stable isotope of copper, once during the 16.5 mg Zn diet and near the beginning and end of the 5.5 mg Zn diet. Apparent copper absorption averaged 48.1% when the 16.5 mg Zn diet was fed. This was significantly higher than the averages of 37.2 and 38.5% when the 5.5 mg Zn diet was fed. Absorption also differed significantly among subjects. Fecal copper did not differ between diets or among subjects. All subjects were in positive copper balance at both levels of dietary zinc. These results suggest that a dietary zinc intake slightly above the Recommended Dietary Allowance of 15 mg/d does not increase fecal copper loss and does not interfere with copper absorption.     

Age Structure and Community Diversity of Nematodes Associated with Maize in Iowa Sandy Soils

Age structure of nematode populations around maize growing in sandy soils in Iowa was studied at soil depths of 0-15and 15-30 cm for 2 years. Numbers of Longidorus breviannulatus were generally greater at 0-15 cm than at 15-30 cm deep until mid to late season. The decline in numbers of females as the season progressed indicates that fecundity slowed and is evidence of only one generation per year. Peak populations of Pratylenchus scribneri and Xiphinema americanum occurred in late August or early September. Adults of Hoplolaimus galeatus were few in the roots but common in the soil, indicating that fertilization occurred mostly in the soil. Numbers of P. scribneri were generally greater at the lower depth, especially late in the season. Community diversity (H'') was less when nematode biomass was used instead of numbers. Numbers of H. galeatus did not decline over the winter. Numbers of L. breviannulatus, P. scribneri, and X. americanum declined significantly over the winter, but not between spring cultivation and planting.     

Molecular motors in axonal transport

Neurons require a large amount of intracellular transport. Cytoplasmic polypeptides and membrane-bounded organelles move from the perikaryon, down the length of the axon, and to the synaptic terminals. This movement occurs at distinct rates and is termed axonal transport. Axonal transport is divided into the slow transport of cytoplasmic proteins including glycolytic enzymes and cytoskeletal structures and the fast transport of membrane-bounded organelles along linear arrays of microtubules. The polypeptide compositions of the rate classes of axonal transport have been well characterized, but the underlying molecular mechanisms of this movement are less clear. Progress has been particularly slow toward understanding force-generation in slow transport, but recent developments have provided insight into the molecular motors involved in fast axonal transport. Recent advances in the cellular and molecular biology of one fast axonal transport motor, kinesin, have provided a clearer understanding of organelle movement along microtubules. The availability of cellular and molecular probes for kinesin and other putative axonal transport motors have led to a reevaluation of our understanding of intracellular motility.     

α-Amylase structural genes in rye

Summary Rye -Amy1, -Amy2, and -Amy3 genes were studied in the cross between inbred lines using wheat -amylase cDNA probes. The -Amy1 and -Amy2 probes uncovered considerable restriction fragment length polymorphism, whereas the -Amy3 region was much more conserved. The numbers of restriction fragments found and the F₂ segregation data suggest that there are three -Amy1 genes, two or three -Amy2 genes, and three -Amy3 genes in rye. These conclusions were supported by a simultaneous study of -amylase isozyme polymorphism. The F₂ data showed the three individual -Amy1 genes to span a distance of 3cM at the locus on chromosome 6RL. The genes were mapped relative to other RFLP markers on 6RL. On chromosome 7RL two -Amy2 genes were shown to be separated by 5 cM. Linkage data within -Amy3 on 5RL were not obtained since RFLP could be detected at only one of the genes.     

Chromosomal location of the genes for ferredoxin in wheat,barley and rye

Communicated by J.W. Snape