Human monocytes selectively bind to cells expressing the tumorigenic phenotype

Summary The characteristics of the binding of human monocytes to tumor cells were studied by a newly developed microassay. First, we determined the kinetics and optimal conditions of the binding. Monocytes recognized and bound to tumor cells very rapidly within 10–20 min of cellular interaction. Binding was also more efficient at 37°C suggesting that active metabolism of monocytes is required. Second, we determined that selective binding of monocytes to cells with tumorigenic phenotypes occurs. For this purpose, lymphocytic leukemia cell lines versus normal lymphocytes, and tumorigenic versus nontumorigenic hybrids from the same parental lines were compared as the targets of the binding assay. In both cases, neoplastic cells were selectively bound by monocytes. Although tumor cells were bound rapidly and selectively by monocytes, initial recognition and binding did not necessarily lead to subsequent tumor cell lysis. This is based on the observation that some tumorigenic parental and hybrid lines were avidly bound by monocytes yet not subsequently killed in a cytotoxicity assay.This work was supported in part by a grant from the National Institutes of Health CA42992 and a grant from the Kleberg foundation Abbreviations used: [¹²⁵I]IdUrd [¹²⁵I]iododeoxyuridine; rIFN-, recombinant human interferon ; IL-1, interleukin 1; rTNF, recombinant human tumor necrosis factor     

p40MO15, a cdc2-related protein kinase involved in negative regulation of meiotic maturation of Xenopus oocytes.

The clone MO15 which codes for a 40 kd protein (p40MO15) with 40% amino acid identity to the human cdc2 protein kinase has been isolated from a Xenopus cDNA library using a synthetic oligonucleotide probe. MO15 mRNA is accumulated during oogenesis, becomes de-adenylated during meiotic maturation, and is degraded after the mid-blastula-transition stage of embryogenesis. Translation of p40MO15 is restricted to non-mature oocytes. Specific inhibition of p40MO15 synthesis in stage VI oocytes by antisense oligonucleotide depletion of MO15 mRNA increases the rate of progesterone induced H1 kinase activation and oocyte maturation. This effect can be reversed by subsequent injection of synthetic MO15 mRNA. These results suggest that p40MO15 is involved in negatively regulating meiosis.     

DEVELOPMENTAL STABILITY IN LEAVES OF CLARKIA TEMBLORIENSIS (ONAGRACEAE) AS RELATED TO POPULATION OUTCROSSING RATES AND HETEROZYGOSITY

Four natural populations of Clarkia tembloriensis, whose levels of heterozygosity and rates of outcrossing were previously found to be correlated, are examined for developmental instability in their leaves. From the northern end of the species range, we compare a predominantly selfing population (t? = 0.26) with a more outcrossed population (t? = 0.84), which is genetically similar. From the southern end of the range, we compare a highly selfing population (t? = 0.03) with a more outcrossed population (t? = 0.58). We measured developmental stability in the populations using two measures of within-plant variation in leaf length as well as calculations of fluctuating asymmetry (FA) for several leaf traits. Growth-chamber experiments show that selfing populations are significantly more variable in leaf length than more outcrossed populations. Developmental instability can contribute to this difference in population-level variance. Plants from more homozygous populations tend to have greater within-plant variance over developmentally comparable nodes than plants from more heterozygous populations, but the difference is not significant. At the upper nodes of the plant, mature leaf length declines steadily with plant age, allowing for a regression of leaf length on node. On average, the plants from more homozygous populations showed higher variance about the regression (MSE) and lower R² values, suggesting that the decline in leaf length with plant age is less stable in plants from selfing populations than in plants from outcrossing populations. Fluctuating asymmetry (FA) was calculated for four traits within single leaves at up to five nodes per plant. At the early nodes of the plant where leaf arrangement is opposite, FA was also calculated for the same traits between opposite leaves at a node. Fluctuating asymmetry is significantly greater in the southern selfing population than in the neighboring outcrossed population. Northern populations do not differ in FA. Fluctuating asymmetry can vary significantly between nodes. The FA values of different leaf traits were not correlated. We show that developmental stability can be measured in plants using FA and within-plant variance. Our data suggest that large differences in breeding system are associated with differences in stability, with more inbred populations being the least stable.     

Disruption of CENP antigen function perturbs dynein anchoring to the mitotic kinetochore

Injection of purified autoantibodies against human centromeric proteins into HeLa cells during interphase disrupts the organization of the kinetochore and interferes with chromosomal movements during the subsequent mitosis even though the chromosomes retain the ability to bind microtubules. We have investigated the hypothesis that this phenotype arises from effects on cytoplasmic dynein, the microtubule motor protein. In previous experiments we found that introduction of anticentromere antibodies into cell nuclei during the G₁- or S-phases causes a prometaphase-like arrest, while injections during G₂-phase cause a metaphase arrest. We show here that, in both cases, the level of detectable cytoplasmic dynein at kinetochores is significantly decreased. In contrast, when injected cells were permitted to enter mitosis in the absence of microtubules (conditions where trilaminar kinetochores could be detected by electron microscopy), the intensity of dynein labeling on the kinetochores was identical to that seen in uninjected control cells exposed to colcemid. Therefore, the loss of dynein label on mitotic kinetochores was correlated both with the injection of anticentromere antibodies and with the presence of intact spindle microtubules. We suggest that the injection of anticentromere antibodies somehow weakens the association of dynein with the kinetochore, so that when microtubules are present, these motor molecules are pulled away from the kinetochores as they generate force. This model offers an explanation for the failure of chromosomes of injected cells to move normally in mitosis even though they have attached microtubules.     

A framework for the analysis of gender,intra-household dynamics,and livestock disease control with examples from Uasin Gishu district,Kenya

As livestock disease control programs in Africa begin to rely more upon para-professionals and livestock producers as deliverers of animal health care services, understanding the role different household members play in providing animal health care becomes increasingly important. This paper presents a framework for the analysis of gender aspects of livestock disease control based on a similar framework developed by Feldstein and Poats (1989). The utility of this framework is illustrated using household-level data collected from a district in central Kenya. Adult women and elderly men in the sample have primary responsibility for livestock care, and are therefore well placed to diagnose illness. Dipping and spraying of animals to prevent tick-borne and other diseases is the primary responsibility of adult males. Decisions regarding use of milk from the morning milking are more likely to be made by adult men. It is morning milk that is most often sold. Adult women, however, make decisions about use of evening milk, which is most often kept for household consumption. Knowledge of livestock diseases did not appear to vary significantly by gender, although some elderly men did possess extensive knowledge of indigenous disease categories and traditional remedies. The importance of recognizing gender issues in planning and implementing livestock disease control programs is discussed.     

CLINES FOR HYBRID DYSFUNCTION IN A GRASSHOPPER HYBRID ZONE

Two subspecies of the grasshopper Chorthippus parallelus meet in the Pyrenees forming a hybrid zone several kilometers wide. Crosses between the two pure taxa result in sterile male offspring and normal females (i.e., Haldane's rule applies). However, no such dysfunction has been detected in hybrid males collected through the center of the hybrid zone. By assessing the level of dysfunction in the offspring of reciprocal crosses, it was possible to map clines for the genes responsible for dysfunction through the zone. This analysis shows that there is no abrupt transition between incompatible genomes in the field. Crosses were also made between females collected from a transect spanning the hybrid zone and pure males of both subspecies. This reveals noncoincident clines for dysfunction near the center of the hybrid zone such that the dysfunction expressed in the offspring of these crosses is less than expected from simple models. More complex models involving interaction among genes must be invoked. Also, the possibility exists that since the postglacial contact of these two grasshopper taxa, hybrid dysfunction has become ameliorated by the evolution of modifiers. This hybrid zone is thought to be a tension zone, maintained by a balance between selection against hybrid genotypes and dispersal into the zone center. The lessening of hybrid disadvantage over time through the breakdown of epistatic interactions by recombination or through modification could account for the general lack of dysfunction in field collected hybrids today.     

Molecular Cloning, Expression, and Pharmacological Characterization of humEAA1, a Human Kainate Receptor Subunit

Abstract: Kainate is a potent neuroexcitatory agent; its neurotoxicity is thought to be mediated by an ionotropic receptor with a nanomolar affinity for kainate. In this report, we describe the cloning of a cDNA encoding a human glutamate ionotropic receptor subunit protein from a human hippocampal library. This cDNA, termed humEAA1, is most closely related to rat and human cDNAs for kainate receptor proteins and, when expressed in COS or Chinese hamster ovary cells, is associated with high-affinity kainate receptor binding. We have successfully established cell lines stably expressing humEAA1. This is the first report of establishment of stable cell lines expressing a glutamate receptor subunit. The relative potency of compounds for displacing [³H] kainate binding of humEAA1 receptors expressed in these stable cell lines was kainate > quisqualate > domoate > L-glutamate > ( RS )-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid > dihydro-kainate > 6, 7-dinitroquinoxaline-2, 3-dione > 6-cyano-7-nitroquinoxaline-2, 3-dione. Homooligomeric expression of humEAA1 does not appear to elicit ligand-gated ion channel activity. Nevertheless, the molecular structure and pharmacological characterization of high-affinity kainate binding of the humEAA1 expressed in the stable cell line (ppEAA1–16) suggest that the humEAA1 is a subunit protein of a human kainate receptor complex.     

Genetic and phylogenetic analyses of human T-cell lymphotropic virus type I variants from Melanesians with an without spastic myelopathy

Molecular variants of human T-cell lymphotropic virus type I (HTLV-I) have been isolated recently from lifelong residents of remote Melanesian populations, including a Solomon Islander with tropical spastic paraparesis/HTLV-I-associated myelopathy (TSP/HAM) or HTLV-I myeloneuropathy. To clarify the genetic heterogeneity and molecular epidemiology of disease-associated strains of HTLV-I, we enzymatically amplified, then directly sequenced representative regions of thegag, pol, env, andpX genes of HTLV-I strains from Melanesians with and without TSP/HAM, and aligned and compared these sequences with those of HTLV-I strains from patients with TSP/HAM or adult T-cell leukemia/lymphoma and from asymptomatic carriers from widely separated and culturally disparate populations. Overall, the HTLV-I variant from the Solomon Islander with TSP/HAM, like HTLV-I strains from asymptomatically infected Melanesians, diverged by approx 7% from cosmopolitan HTLV-I strain. No disease-specific viral sequences were found. Gene phylogenies, as determined by the unweighted pair-goup method of assortment and by the maximum parsimony method, indicated that the Melanesian and cosmopolitan strains of HTLV-I have evolved along separate geographically dependent lineages, one comprised of HTLV-I strains from Papua New Guinea and the Solomon Islands, and the other composed of virus strains from Japan, India, the Caribbean, Polynesia, the Americas, and Africa. The total absence of nonhuman primates in Papua New Guinea and the Solomon Islands precludes any possibility that the Melanesian HTLV-I strains have evolved recently from the simian homolog of HTLV-I.