Ascorbic acid promotes graft-take in sweet pepper plants (Capsicum annuum L.)

The cause of the low survival rate of sweet pepper plants after grafting was investigated and compared with findings of eggplant and tomato plants, and the promotive effect of ascorbic acid (AA) was determined. Sweet pepper plants formed less callus at the cut surfaces of the stem compared to eggplant and tomato plants. Foliar application with 100 mg L⁻¹ AA promoted callus formation at the cut surfaces of the scion stems and improved the survival rate after grafting. We suggest that the low survival rate of grafted sweet pepper plants is caused by their low rate of callus formation, and that AA can be used to promote graft-take through the acceleration of callus formation at the cut surfaces of the stems.     

Effects of explant position and dark treatment on bud formation in floret culture of Ponerorchis graminifolia Rchb.f

An efficient method of micropropagation was investigated for Ponerorchis graminifolia. Shoot apexes and florets with inflorescence nodes were used as explants for in vitro cultures. A high efficiency of bud formation was observed on half-strength MS medium containing 4.44 μM N⁶-benzyladenine (BA) and 0.54 μM α-naphthaleneacetic acid (NAA) using florets from upper positions of inflorescences as explants. However, the explants frequently exuded browning compounds into the media during culture. Dark treatment, a countermeasure, decreased exudation of the browning compounds during floret culture. When shoot apexes from dark treated florets were used as an explant material after the floret culture, the dark-pretreated shoot apexes developed 2.2 buds per explant, compared with 1.2 buds per explant from light pretreated shoot apexes, and showed decreased exudation of browning compounds. These results suggest that the most suitable explants for bud formation in P. graminifolia are top florets and shoot apexes derived from the floret culture with dark treatment.     

Changes of serum 3-methylhistidine concentration and energy-associated metabolites in dairy cows with ketosis

The present study examined the Serum 3-methylhistidine concentrations and energy-associated variables of 5 healthy Holstein cows and 5 Holstein cows with ketosis. The serum total cholesterol and apolipoprotein B-100 concentrations and lecithin-cholesterol acyltransferase (LCAT) activity of the ketotic cows were lower than those of the healthy cows 14 days before parturition. The serum non-esterified fatty acid (NEFA) concentration on the day of parturition and 3-methylhistidine concentration 14 days after parturition were higher in the ketotic cows. The serum 3-methylhistidine concentration 14 days after parturition was negatively correlated with the serum LCAT activity 14 days before parturition and was positively correlated with the serum NEFA concentration on the day of parturition. Insufficiency of cholesterol metabolism and acceleration of body fat degradation occur before parturition in cows with ketosis, and these characteristics are correlated with acceleration of protein degradation after parturition.     

Cardiovascular and renal effects of constant rate infusions of remifentanil, dexmedetomidine and their combination in dogs anesthetized with sevoflurane

We evaluated changes in cardiovascular and renal functions as well as arginine vasopressin (AVP) secretion, with remifentanil and dexmedetomidine administration alone or in combination in sevoflurane-anesthetized dogs. Six healthy adult Beagle dogs received one of the following four treatments in a randomized crossover study: saline (C), remifentanil alone at successively increasing doses (R; 0.15, 0.60, and 2.40 µg/kg/min), dexmedetomidine alone (D; 0.5 µg/kg intravenously for initial 10 min followed by a constant rate infusion at 0.5 µg/kg/hr), and a combination of remifentanil and dexmedetomidine at the above-mentioned doses (RD). Sevoflurane doses were adjusted to 1.5 times of minimum alveolar concentration (MAC) equivalent according to MAC-sparing effects with remifentanil and dexmedetomidine as previously reported. Cardiovascular measurements, renal function data, and plasma AVP concentrations were determined before and every 60 min until 180 min after drug administration as per each treatment. In the R, D and RD, heart rate significantly decreased and mean arterial pressure significantly increased from baseline or with C. Cardiac index significantly decreased and systemic vascular resistance index increased with D and RD. Oxygen extraction ratio, renal blood flow, and glomerular filtration rate were not affected. The plasma AVP concentrations significantly decreased in D and RD, but increased in R. Only in D, the natriuresis was elicited. The combination of remifentanil and dexmedetomidine in sevoflurane-anesthetized dogs was acceptable in terms of the hemodynamics, oxygenation, and renal function. Remifentanil may interfere with dexmedetomidine-induced diuresis and inhibition of AVP secretion.     

Causes of defoliation and low survival rate of grafted sweet pepper plants

We investigated the cause of defoliation in sweet pepper (Capsicum annuum L.) plants after grafting. Grafted plants of old-stage sweet pepper showed a higher defoliation rate than young-stage grafted plants. Old-stage grafted plants had lower stomatal resistance and water potential than young-stage plants, and showed poorly developed xylem connections at the graft site. Foliar application of abscisic acid (ABA) to the grafted plants increased stomatal resistance and water potential, decreased the defoliation rate, and promoted graft take among old-stage plants. Our results indicated that low stomatal resistance under low humidity induces water stress, defoliation, and low survival rate in old-stage grafted sweet pepper plants. ABA treatment increased stomatal resistance, water potential, and survival rate, and decreased the defoliation rate among old-stage sweet pepper plants.