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Glyphosate [N‐(phosphonomethyl)glycine] herbicide can be topically applied twice at rates as high as 0.84 kg a.e. (acid‐equivalent) ha−1to glyphosate‐resistant cotton (Gossypium hirsutumL.) cultivars until the fourth true leaf stage, with the requirement of at least 10 d and two nodes of growth between applications. But, such cultivars are not reproductively resistant to glyphosate applied topically or imprecisely directed after the four‐leaf stage because glyphosate can curtail pollen development and ovule fertilization, which potentially reduces yield. Extending glyphosate resistance past the four‐leaf stage would provide growers with additional weed management options. Our objective was to test under field conditions glyphosate resistance of cotton germplasm transformed with gene constructs previously shown to impart extended glyphosate resistance in the greenhouse. Four or six transgenic cotton lines containing one of several constructs conferring extended glyphosate resistance, plus the current glyphosate‐resistant control (‘Coker 312’‐1445), were tested at nine U.S. locations in 2001. Within locations, treatment designs consisted of cross‐classified arrangements of transgenic lines and glyphosate rates [0, 1.68, and 2.52 kg a.e. ha−1]. Treated plots received glyphosate over‐the‐top of cotton at four growth stages (3‐, 6‐, 10‐, and 14‐leaf crop stages). Compared with Coker 312‐1445, extended glyphosate resistance was expressed as higher yields when glyphosate was applied topically at the four growth stages. Mature plant mapping confirmed extended glyphosate resistance of the new transgenic cotton through similar fruit distribution and weight with or without glyphosate treatment. The capability to apply glyphosate topically to cotton later in crop development will facilitate weed management and could reduce dependence on directed herbicides.

Female Long Evans hooded rats with an initial mean (± SE) weight of 85.7 ± 1.2 g were exposed to 5 ppm cadmium (Cd) in drinking water for 6 months. Rats which received no Cd in the drinking water served as untreated controls. Weights, systolic blood pressures (tail cuff method), several aspects of aortic ultrastructure, and isolated aortic contractile responses to epinephrine, angiotensin, and potassium chloride at 0, 1, 2, 3, and 6 months were observed in both groups. At none of the testing times was there a significant difference between the weights or systolic blood pressures of the control and Cd-treated groups. Analysis of variance indicated that aortas from control and Cd-treated rats showed similar age-related changes in maximum tension development (contractility) and similar threshold doses. However, Cd-treated aortas developed significantly less maximum tension than control aortas when compared at the same time intervals in response to all of the vasoconstrictors tested. This decreased contractility was apparent at one month and persisted at about the same level (20%) at 2, 3, and 6 months. There were also expected age-related changes in aortic ultrastructure of both groups, and although the 6-month Cd-treated aortas showed more degenerating endothelial cells, differences that might explain the consistent decreases in contractility of the Cd-treated aortas were not observed. The results of this study indicate that chronic low-level Cd treatment causes decreases in aortic contractility, as have previously been reported for acute exposure to Cd, but that this change is not associated with the development of hypertension or with structural changes in the aorta.

The blood pressure responses of normotensive (WKY) and hypertensive (SHR) rats to histamine injections were compared before and during pregnancy. A series of increasing doses of intravenous histamine was given before histamine receptor blockade, after H1 (pyrilamine) block, and after combined H1 and H2 (cimetidine) block. In both WKY and SHR nonpregnant rats, histamine caused dose-dependent decreases in blood pressure which were partially dependent on H1 and H2 receptors. In late pregnancy, the magnitudes of the hypotensive effects of histamine were significantly reduced and blocked only by combined H1 and H2 treatment but not by H1 treatment alone. Thus, the blood pressure effects of exogenous histamine in normotensive and hypertensive rats are modified in a similar way during late pregnancy with diminished hypotensive effects which are more dependent on H2 receptors than the effects in nonpregnant rats. This change in histamine responsiveness may play a role in the cardiovascular adjustments of pregnancy.

A novel formulation of cypermethrin was applied as a bath treatment to Atlantic salmon infested with sea lice on a commercial fish farm on the Isle of Skye, Scotland. Twenty 15 m × 15 m cages were treated with cypermethrin at a concentration of 5 μg/litre sea water. The numbers of sea lice of all stages were recorded on five fish per cage before the treatment and one, seven and 16 days after treatment. Statistically significant reductions in the numbers of chalimus III and IV pre‐adults and adults were recorded over the whole period; the average percentage reductions at one and 16 days after treatment were 59 per cent and 90 per cent (chalimus III and IV), 98 per cent and 95 per cent (pre‐adults), and 99 per cent (adults), respectively.

A letter to the editor is presented in response to the article "Does High Technology Need Fed Funds" by Jack Gibbons in the April 10, 1995 issue.

Several letters to the editor are presented in response to articles published in previous issues, including "Gilder's Telecosm: The $2 Trillion Opportunity," "Does High Technology Need Fed Funds?" and "Two Cheers for Pissed Off," all in the April 10, 1995 issue.