Modification of the skin feeding site by tick saliva mediates virus transmission.

A tick vector of Thogoto (THO) virus was shown to secrete a factor in saliva which potentiates the transmission of THO virus to uninfected ticks feeding on an apparently non-viraemic host. The effect of the saliva activated transmission (SAT) factor on the virus occurred at the site of inoculation in the skin and was apparent even when the virus was introduced 3 days after the SAT factor. The results suggest that tick saliva can play an important role in disease transmission by virtue of host modification at the site of feeding.     

β-Endorphin in normozoospermic and pathologic human semen

Summary -Endorphin was estimated in normozoospermic, oligozoospermic and azoospermic human semen. The mean amount in normozoospermic specimens was 278.6±43.6 (SE) pg/ml while in the others only 191.1±25 pg/ml. Both values are significantly higher than those present in the blood.     

Isolation and characterization of genomic and cDNA clones of human erythropoietin

The glycoprotein hormone erythropoietin regulates the level of oxygen in the blood by modulating the number of circulating erythrocytes, and is produced in the kidney or liver of adult and the liver of fetal or neonatal mammals. Neither the precise cell types that produce erythropoietin nor the mechanisms by which the same or different cells measure the circulating oxygen concentration and consequently regulate erythropoietin production are known. Cells responsive to erythropoietin have been identified in the adult bone marrow, fetal liver or adult spleen. In cultures of erythropoietic progenitors, erythropoietin stimulates proliferation and differentiation to more mature red blood cells. Detailed molecular studies have been hampered, however, by the impurity and heterogeneity of target cell populations and the difficulty of obtaining significant quantities of the purified hormone. Highly purified erythropoietin may be useful in the treatment of various forms of anaemia, particularly in chronic renal failure. Here we describe the cloning of the human erythropoietin gene and the expression of an erythropoietin cDNA clone in a transient mammalian expression system to yield a secreted product with biological activity.     

Ethanol-induced chromosomal abnormalities at conception

Preliminary findings have indicated that mouse eggs exposed briefly in vivo or in vitro to a dilute solution of ethanol activate parthenogenetically. Cytogenetic analysis of the first-cleavage chromosomes of haploid parthenogenetic embryos indicated that up to 20% of this population were aneuploid as a result of non-disjunction. Anaesthetics also can induce parthenogenesis of rodent eggs, and in studies using anaesthetics, colchicine and colcemid, abnormal chromosome segregation and heteroploidy of rodent embryos have been observed. I now report that when recently mated female mice are given a dilute solution of ethanol by mouth, non-disjunction can be induced in the female-derived, but apparently not in the male-derived, chromosome set of fertilized eggs. Taken together, these findings suggest that ethanol consumption (as well as exposure to other 'spindle-acting' agents) at the time of conception may be the cause of certain types of chromosomal defects commonly observed in human spontaneous abortions.     

Phenotypic expression in E. coli of a DNA sequence coding for mouse dihydrofolate reductase.

The construction and analysis of bacterial plasmids that contain and phenotypically express a mammalian genetic sequence are described. Such plasmids specify a protein that has enzymatic properties, immunological reactivity and molecular size characteristic of the mouse dihydrofolate reductase, and render host cells resistant to the antimetabolic drug trimethoprim.