Adrenocortical response to ACTH in Angora and Spanish goat wethers.

Angora goats do not cope well with stress compared with goats of other breeds. Our hypothesis that this involves subclinical primary hypoadrenocorticism associated with low cortisol release in response to ACTH stimulation was tested by measuring adrenocortical response (plasma cortisol) in six Spanish (37 +/- 2 kg BW) and six Angora wethers (39 +/- 3 kg BW) under simulated acute and chronic ACTH challenges. In Exp. 1 (acute ACTH challenge), wethers were dosed i.v. with high (2.5 IU/kg BW) or low (.4 IU/kg BW) quantities of ACTH. In Exp. 2 (chronic ACTH challenge), ACTH at the rate of .015 IU/(kg BW x min) or saline (.15 M NaCl) was infused i.v. at 15 mL/h for 6 h. The mean baseline plasma cortisol concentration before ACTH stimulation was similar (P > .05) between Angora and Spanish goats in Exp. 1 (averaged over days) and in Exp. 2. The cortisol concentration response area (ng/ (mL x min) x 10(-3)) above the baseline was similar (P > .05) between Angora and Spanish goats during low (7.6 +/- .5 and 9.0 +/- 1.7, respectively) and high (12.8 +/- 1.0 and 16.0 +/- 1.8, respectively) levels of acute ACTH challenge (Exp. 1) and during chronic ACTH challenge (45.1 +/- 5.9 and 41.8 +/- 7.3, respectively; Exp. 2). In conclusion, these data indicate that, under the conditions of this study, adrenocortical responsiveness to ACTH stimulation is not different between Angora and Spanish goat wethers and, thus, may not contribute to stress susceptibility in Angora goats.     

Laboratory evaluation of dual-frequency multisensor capacitance probes to monitor soil water and salinity

Real-time information on salinity levels and transport of fertilizers are generally missing from soil profile knowledge bases. A dual-frequency multisensor capacitance probe (MCP) is now commercially available, for sandy soils, to simultaneously monitor volumetric soil water content (VWC) measured as a percentage and salinity as a unitless volumetric ion content (VIC). The objectives of this research were to assess the relationship of salinity and water content with these dual-frequency MCPs under laboratory conditions, and assess its potential for field use in sandy soils of the mid-Atlantic region of the US. Water and salinity studies were conducted in two sand-filled PVC columns, 1.2 m long by 0.25 m ID. Each column was instrumented with ten dual-frequency capacitance sensors and two thermocouple temperature sensors. Four salinity levels were studied in the two columns using 0.5, 1, 2, and 4 dSm⁻¹ NH₄NO₃ solutions. Water, salinity, and temperature readings were continuously recorded at 1-min intervals. The VIC values were found to be primarily qualitative, but combined with real-time VWC measures the probe could still be an important fertigation management tool to provide near-continuous real-time information on fertilizer penetration, spread and subsequent changes during crop growth.

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Beech leaf disease symptoms caused by newly recognized nematode subspecies Litylenchus crenatae mccannii (Anguinata) described from Fagus grandifolia in North America

Symptoms of beech leaf disease (BLD), first reported in Ohio in 2012, include interveinal greening, thickening and often chlorosis in leaves, canopy thinning and mortality. Nematodes from diseased leaves of American beech (Fagus grandifolia) sent by the Ohio Department of Agriculture to the USDA, Beltsville, MD in autumn 2017 were identified as the first recorded North American population of Litylenchus crenatae (Nematology, 21, 2019, 5), originally described from Japan. This and other populations from Ohio, Pennsylvania and the neighbouring province of Ontario, Canada showed some differences in morphometric averages among females compared to the Japanese population. Ribosomal DNA marker sequences were nearly identical to the population from Japan. A sequence for the COI marker was also generated, although it was not available from the Japanese population. The nematode was not encountered in Fagus crenata (its host in Japan) living among nematode‐infested Fagus grandifolia in the Holden Arboretum, nor has L. crenatae been reported in American beech in Japan. The morphological and host range differences in North American populations are nomenclaturally distinguished as L. crenatae mccannii ssp. n. from the population in Japan. Low‐temperature scanning electron microscopy (LT‐SEM) demonstrated five lip annules and a highly flexible cuticle. Females, juveniles and eggs were imaged within buds with a Hirox Digital microscope and an LT‐SEM. Nematodes swarmed to the tips of freshly cut beech buds, but explants could not be maintained. Inoculation of fresh nematodes from infested leaves or buds to buds or leaves of F. grandifolia seedlings resulted in BLD leaf symptoms. Injuring dormant buds prior to nematode application, in fall or spring, promoted the most reliable symptom expression. The biogeography and physiology of anguinid nematode leaf galling, and potential co‐factors and transmission are discussed.     

Effect of Sildenafil on Pre‐Eclampsia‐Like Mouse Model Induced By L‐Name

N(omega)‐nitro‐L‐arginine methyl ester (L‐NAME) decreases the vasodilator effect of nitric oxide (NO) and induces pre‐eclampsia in mouse. Sildenafil inhibits the degradation of nitric oxide and increases vasodilation. This study aimed to determine the effects of sildenafil citrate on angiogenesis and oxidative stress at the maternal foetal interface on pre‐eclampsia‐like mouse model induced by L‐NAME. Twenty pregnant mice were divided into four groups: (i) vehicle control; (ii) L‐NAME; (iii) sildenafil; (4) L‐NAME+sildenafil. L‐NAME was administered from day 7 of pregnancy and sildenafil from day 8 until day 16; animals were euthanized on day 17. Placental and foetal sizes and weights were measured; lipid peroxide levels and catalase activity in placental homogenates were determined, and placental vascular endothelia were identified by lectin‐histochemistry using BSA‐I lectin. Western blot analysis was used to determine VEGF expression in placental homogenates. No changes were seen in placental and foetal development in mice with normal pregnancies treated with sildenafil. Treatments with L‐NAME reduced significantly the placental weight and average height and decreased the percentage of the endothelial surface. These alterations may be mediated by the reduction of NO levels in trophoblastic cells, due to the inhibitory effect of L‐NAME on nitric oxide synthase (NOS) synthesis. This effect was offset by the treatment with sildenafil, with an increase in the percentage of the endothelial surface. In conclusion, our results indicate that treatment with sildenafil on pre‐eclampsia mouse model can be used without adverse effects on the concept and its use in the treatment of pre‐eclampsia is promising.     

Chemical Usurpation of a Nest by Paper Wasp Parasites

The paper wasp Polistes atrimandibularis is an obligatory social parasite of another Polistes species, P. biglumis bimaculatus. To control the host nest, the parasite sequentially changes the composition of its chemical signature, the cuticular hydrocarbons, during the colonial cycle. Gas chromatography-mass spectrometry of the cuticular hydrocarbons at every stage of the cycle showed that the parasite can switch on and off an entire chemical family, namely, the unsaturated hydrocarbons. In this way the parasite can match the host signature at a critical moment of the colonial cycle.     

Zone-subsoiling effects on potato yield and grade

Soil compaction and erosion are problems in many Pacific Northwestern potato fields. We wanted to determine if zone-subsoiling would reduce these problems and improve potato yields and or grade without adversely impacting other production practices. Studies were conducted in Southern Idaho at six locations over two years on different soils and with different irrigation methods to assess the effects of zone-subsoiling immediately after planting on tuber yield and grade. Reservoir-tillage comparisons were made at three locations where sprinkler water application rates were higher than soil infiltration rates. Russet Burbank was represented by eight location-years and Russet Norkotah by two. Zone-subsoiling consistently improved tuber grade or increased tuber size. The biggest improvement was under furrow irrigation. Zone-subsoiling also tended to increase total yield in eight of ten location-years. Reservoir-tillage improved yield and grade, but zone-subsoiling did not without reservoir-tillage when water application rates were high. At no location did zone-subsoiling significantly decrease tuber grade or yield. Zone-subsoiling had no appreciable effects on hill configuration or seed-piece dislocation. Surface cracking and “water piping” occurred under furrow irrigation but were not significant problems. Results were similar for both cultivars. Additional studies will be needed to successfully incorporate zone-subsoiling into commercial production practices     

Optimal allocation of limited water supplies for Russet Burbank potatoes

Water shortages in many potato-producing regions have increased the demand for information on irrigating potatoes with limited water supplies. Field studies were conducted at Aberdeen, Idaho in 1988 and 1989 to determine the optimal allocation of limited water supplies for Russet Burbank potatoes. Irrigation amounts equal to 60 or 80% of estimated seasonal evapotranspiration (ET) were applied using various patterns of water allocation. Irrigation deficits were either partitioned evenly over the entire tuber bulking period, or were imposed during two of three designated growth stages (early, mid or late bulking) corresponding to the periods from 0 to 3, 3 to 6, and 6 to 9 weeks after tuber initiation, respectively. A well-watered, 100% ET check was included for comparison. Total yield reductions were greater when irrigation deficits were imposed during the early-mid and midlate bulking sequences than when they were imposed evenly over the entire tuber bulking period or during the early-late bulking sequence. Results relating U.S. No. 1 yields to seasonal water allocation patterns were similar to those for total yield. However, U.S. No. 1 yield reductions were proportionately greater. Irrigation deficits imposed during the early-mid bulking sequence resulted in the lowest specific gravities and the highest percentages of dark ends.