Hydrogen cyanide production by soil bacteria: Biological control of pests and promotion of plant growth in sustainable agriculture

Currently, plant diseases and insect infestations are mainly controlled by the extraneous application of pesticides. Unfortunately, the indiscriminate use of such agrochemicals can cause ecological and environmental problems, as well as human health hazards. To obviate the potential pollution arising from the application of agrochemicals, biological control of soilborne pathogens or insect pests using antagonistic microorganisms may be employed. Certain soil bacteria, algae, fungi, plants and insects possess the unique ability to produce hydrogen cyanide(HCN), which plays an important role in the biotic interactions of those organisms. In particular, cyanogenic bacteria have been found to inhibit the growth of various pathogenic fungi, weeds, insects, termites and nematodes. Thus, the use of HCN-producing bacteria as biopesticides offers an ecofriendly approach for sustainable agriculture. The enzyme, HCN synthase,involved in the synthesis of HCN, is encoded by the hcnABC gene cluster. The biosynthetic regulation of HCN, antibiotics and fluorescent insecticidal toxins through the conserved global regulatory GacS/GacA system is elaborated in this review, including approaches that may optimize cyanogenesis for enhanced pest control. In addition, the effects of bacterially synthesized HCN on the production of indole acetic acid, antibiotics and fluorescent insecticidal toxins, 1-aminocyclopropane-1-carboxylate deaminase utilization and phosphate solubilization may result in the stimulation of plant growth. A more detailed understanding of HCN biosynthesis and regulation may help to elaborate the precise role of this compound in biotic interactions and sustainable agriculture.     

Seroprevalence and comparison of isolates of endometriotropic bovine herpesvirus-4.

Sixty-eight cases of suppurative, ulcerative endometritis associated with Bovine Herpesvirus-4 (BHV-4) in postparturient dairy cows (62 Holsteins and 6 Jerseys, mean age 4.2 years) were confirmed by a combination of histopathology, fluorescent antibody assays, electron microscopic evaluation of uterus, and polymerase chain reaction (PCR). All cases occurred in the 3- to 28-day postpartum period, and histologic lesions among various cows were consistent when compared with postpartum interval. The endometrial lining epithelium was necrotic and ulcerated from 3 to 7 days postpartum, with only mild inflammation in the lamina propria and submucosa. From 1 to 4 weeks postpartum, the ulcers were confluent to diffuse. Epithelium was replaced by fibrinonecrotic, suppurative mats, resulting in severe bacterial pyometra by day 24. Seroprevalence to BHV-4 in one dairy with a history of 18 mortality cases was 36% (107 of 296). In a random sample of 8 cows from this herd, none had serologic titers in blood sampled 2 weeks prepartum, but 3 of 8 seroconverted with significant titers of 1:8 to 1:16 at 2 weeks postpartum. By 10 weeks postpartum, all 8 cows returned to negative serologic status. Two of 6 cats from the premises also had positive titers. Random serum samples taken from 480 dairy cattle at sale barns indicated 76 (16%) were positive by serum neutralization. Clinical signs, postparturient timing, and histologic lesions were very similar to those previously reported in Belgium with BHV-4. But sequence analysis of PCR products of the glycoprotein B region of 4 separate field isolates of endometriotropic BHV-4 suggests these field isolates were more closely related to the North American nonvirulent strain DN-599 than to the endometriotropic European strain V.     

Signs of Sympathetic Denervation Associated With a Thoracic Melanoma in a Horse

Sympathetic denervation in a 20-year-old, gray, Thorough-bred-Percheron gelding was manifested by cutaneous hyperthermia and sweating over the right side of the body, demarcated by a line from the withers to the elbow and extending cranially. There was cutaneous hyperthermia over the right side of the head, but other signs of Horner's syndrome (sweating, ptosis, miosis, enophthalmos) were not present. The pattern of cutaneous hyperthermia and sweating was consistent with sympathetic denervation localized to the cervicothoracic ganglion, and thoracic radiographs revealed increased density in the craniodorsal thorax. Cytologic evaluation of a sample of pleural effusion revealed mesothelial cells containing melanin and cells suggestive of melanocytes or melanoblasts. Treatment with oral cimetidine and intrapleural cisplatin was not successful. A necropsy was not performed, but the clinical findings supported a diagnosis of thoracic melanoma involving the cervicothoracic ganglion.     

Treatment of a recurrent ocular squamous cell carcinoma in a horse with Iridium-192 implantation

A 7-year-old Selle français gelding was presented for a recurrent conjunctival tumour on the left eye. A previous histologic analysis revealed a conjunctival squamous cell carcinoma. As it was the third recurrence after surgical excision in a 1½-year period, we decided to perform interstitial radiotherapy combined with the surgical excision. Two Iridium-192 pins were implanted in the subcutaneous fascia of the lower eyelid over the tumor site and were removed 3 days later. No postoperative adverse reactions were observed. Twelve months postoperatively, there were no signs of local recurrence. Surgical excision combined with Iridium-192 therapy appeared to be an effective treatment in this case.     

Feline injection site sarcomas.

Feline injection site sarcomas have mostly been associated with the administration of vaccines. Although the pathogenesis remains largely unknown, it is believed the inflammatory reaction caused by the injection of the compound leads to uncontrolled proliferation of fibroblasts and myofibroblasts that may undergo malignant transformation in a subset of cats. Pretreatment evaluation and proper planning of therapy are essential. Currently, because of the aggressive nature of these tumors, a multimodality treatment approach is recommended.     

Effect of the methodology on circulating peptides determination and consequences on net flux measurements across the gastrointestinal tract of sheep.

Two methodologies for the measurement of peptide amino acids (PAA) in blood were compared to evaluate their effects on the measurement of the net flux of peptides across the gastrointestinal tract of sheep. These methods consisted of a chemical deproteinization of blood samples with sulfosalicylic acid (1.6 M, 0.1 ml for 1 ml of sample) or perchloric acid (1 M, 1 ml for 1 ml of sample) followed by ultrafiltration through a 3,000-Da cut-off filter (SSA + UF3 kD) or gel filtration through a Sephadex G-15 column (1,500-Da cut-off filter; PCA + G-15), respectively, prior to PAA analysis. Peptide concentrations as determined by amino acid concentrations before and after hydrolysis of samples were slightly greater with the SSA + UF3 kD (991 microM) than with the PCA + G-15 (605 microM) methodology. However, both methodologies gave similar net portal-drained viscera flux data in sheep fed on alfalfa pellets with histidine as the only significant uptake of peptide amino acid.     

Remittances sent by a growing altruistic diaspora: How do they grow over time?

Abstract: This paper investigates theoretically the time pattern of remittances sent home by a growing diaspora of emigrants who are motivated by altruism rather than pure self‐interest. Migrants are assumed to care about the consumption of home‐resident family members as well as their own welfare. Hence, remittance effort will depend upon the ratios of per capita income and income growth rates between the host country and the home country. Effort will depend also on the number of emigrants sending back remittances to each home‐resident household. In general, the effect of remittances is to sustain growth of consumption per capita in the home country above the growth rate of per capita GDP. A priori, there is no necessary tendency for remittance effort to rise or fall over time. Falling remittance amounts per migrant may occur as the diaspora grows relative to the home population, but should not be treated as evidence of so‐called ‘remittance fatigue’. A number of feasible scenarios are traced out, and some opportunities are identified to use statistical tests to adjudicate between self‐interest and altruism as motives for sending remittances.