First Report of Ophiosphaerella herpotricha Causing Spring Dead Spot of Bermudagrass in Mississippi

Spring dead spot (SDS) is the most destructive disease of bermudagrass (Cynodon dactylon (L.) Pers.). Symptoms of SDS appear in the spring when bermudagrass transitions out of winter dormancy. These symptoms include depressed, straw-colored patches that range from several centimeters to a meter in diameter. Infected roots and rhizomes are black, brittle, and necrotic. The disease is caused by three species of fungi: Ophiosphaerella herpotricha (Fr:Fr) J. Walker; O. korrae (J. Walker & A.M. Smith) Shoemaker & C.E. Babcock; or O. narmari (J. Walker & A.M. Smith) Wetzel, Hubert & Tisserat. However, O. korrae is the most prevalent causal organism of SDS in the southeastern United States and was the only species reported in Mississippi (1). In April of 2006, root samples were collected from a bermudagrass putting green in Booneville, MS with a high level of SDS incidence and severity. Symptomatic roots were collected and surface disinfested in 0.6% NaOCl and plated on one-quarter-strength potato dextrose agar (PDA) amended with streptomycin sulfate and chloramphenicol. Hyphae growing from the roots were transferred to full-strength PDA after 5 to 7 days. Mycelium from five pure-culture colonies plus an O. herpotricha control was harvested after 4 weeks of growth and the genomic DNA was extracted. The genomic DNA of the Booneville isolates and the O. herpotricha control were amplified by PCR using species-specific primers OHITS1 and OHITS2 for O. herpotricha (2). Amplification of a 454-bp fragment of DNA confirmed one of the five unknown isolates as O. herpotricha. The other four isolates were not identified. 'Sahara' bermudagrass (4 weeks old in 3.8 × 20 cm Cone-tainers containing a sand and soil mixture) was inoculated with the Booneville-O. herpotricha isolate and the O. herpotricha control. One gram of oat seed infested with O. herpotricha isolates was inserted 2 cm below the crowns in the root zone of bermudagrass plugs. The inoculated bermudagrass plants were incubated for 4 weeks in the greenhouse. A control consisting of noninfested sterile oats was included. Following incubation, black, necrotic roots were observed on the plants inoculated with both O. herpotricha isolates. No symptoms were observed on roots of noninfested plants. Symptomatic roots were disinfested and plated on one-quarter-strength PDA. Koch's postulates were completed after O. herpotricha was reisolated from roots of plants inoculated with both O. herpotricha isolates and confirmed by PCR as mentioned above. The identification of O. herpotricha as a causal organism of SDS in Mississippi clarifies the involvement of multiple causal agents in this state and broadens the geographic distribution of this root-rot species. References: (1) F. B. Iriarte et al. Plant Dis. 88:1341, 2004. (2) N. A. Tisserat et al. Phytopathology 84:478, 1994.

Evaluation of transgenic cotton varieties and a glyphosate application on seedling disease incidence

A study was conducted to determine whether stand densities of transgenic cotton (Gossypium hirsutum) varieties, with or without glyphosate, were similar to conventional varieties of the same lineage group in Georgia and Mississippi. Transgenic and conventional cotton varieties were placed into five lineage groups of related varieties and seedling disease was evaluated in three greenhouse tests and a field trial using Rhizoctonia solani AG-4. Seed vigor was determined by standard germination studies were conducted evaluating conventional and transgenic varieties of similar lineage. Results showed that no interactions occurred for the heights and dry weight data across treatments within the lineage groups in any of the experiments. No interactions were shown between stand densities at different inoculum rates and inoculated versus uninoculated pots (plots). Across all greenhouse studies, stand counts of PM 1220 were similar to the transgenic varieties PM 1220 RR and PM 1220 B/RR with or without a glyphosate application. In the field trial, PM 1220 B/RR + glyphosate had significantly lower stands than all other treatments expect PM 1220 RR (no glyphosate treatment) prior to and after glyphosate application. Stand densities for varieties within the lineage group DPL 5415 were also inconsistent when compared between the greenhouse and field trials with no apparent trends occurring. However, the Coker 312 varieties containing glyphosate tolerance had consistently lower stand counts compared to the conventional variety of Coker 312 but only during the greenhouse studies. Seed germination of Coker 312 could not be correlated with either the greenhouse or field trial data. In general, the commercially available varieties such as PM 1220, DPL 5690, DPL 5415, and DPL 50 with glyphosate tolerance had similar stand count, height, and dry weight data when compared to the conventional varieties from the same lineage group regardless of a glyphosate application. When differences did occur, no consistent trends could be determined within these four lineage groups.

Management of Mason type-III radial head fractures with a titanium prosthesis, ligament repair, and early mobilization. Surgical technique

BACKGROUND

Radial head fractures often occur in association with other elbow fractures and soft-tissue injuries. Radial head replacement is indicated for irreparable radial head fractures associated with elbow instability. The purpose of this study was to analyze the results after treatment of such injuries with a titanium radial head prosthesis, repair of torn collateral ligaments, and early mobilization of the elbow.

MATERIALS

Sixteen patients with sixteen Mason type-III radial head fractures and collateral ligament injury were treated with use of a titanium radial head prosthesis over a five-year period at the Royal Adelaide Hospital and Modbury Public Hospital in South Australia. The surgery was performed acutely in ten patients and was delayed an average of thirty-seven days (range, fifteen to seventy-nine days) in six. All patients were followed clinically and radiographically for a mean of 2.8 years (range, 1.2 to 4.3 years).

RESULTS

Eight patients had an excellent result; five, a good result; and three, a fair result, according to the Mayo Elbow Performance Score. The three fair results occurred in patients with delayed surgery. The mean flexion contracture was 15 degrees (range, 0 degrees to 42 degrees ), with an average loss of 10 degrees (range, 0 degrees to 25 degrees ) of full flexion compared with that of the contralateral elbow. Both pronation and supination decreased an average of 12 degrees (range, 0 degrees to 45 degrees ) compared with that of the contralateral forearm.

CONCLUSIONS

The results of treatment of Mason type-III radial head fractures with a monoblock titanium radial head prosthesis and soft-tissue reconstruction are satisfactory. Early mobilization of the elbow is important for the restoration of elbow range of motion and function.

Evaluation of transgenic cotton varieties and a glyphosate application on seedling disease incidence

A study was conducted to determine whether stand densities of transgenic cotton (Gossypium hirsutum) varieties, with or without glyphosate, were similar to conventional varieties of the same lineage group in Georgia and Mississippi. Transgenic and conventional cotton varieties were placed into five lineage groups of related varieties and seedling disease was evaluated in three greenhouse tests and a field trial using Rhizoctonia solani AG-4. Seed vigor was determined by standard germination studies were conducted evaluating conventional and transgenic varieties of similar lineage. Results showed that no interactions occurred for the heights and dry weight data across treatments within the lineage groups in any of the experiments. No interactions were shown between stand densities at different inoculum rates and inoculated versus uninoculated pots (plots). Across all greenhouse studies, stand counts of PM 1220 were similar to the transgenic varieties PM 1220 RR and PM 1220 B/RR with or without a glyphosate application. In the field trial, PM 1220 B/RR + glyphosate had significantly lower stands than all other treatments expect PM 1220 RR (no glyphosate treatment) prior to and after glyphosate application. Stand densities for varieties within the lineage group DPL 5415 were also inconsistent when compared between the greenhouse and field trials with no apparent trends occurring. However, the Coker 312 varieties containing glyphosate tolerance had consistently lower stand counts compared to the conventional variety of Coker 312 but only during the greenhouse studies. Seed germination of Coker 312 could not be correlated with either the greenhouse or field trial data. In general, the commercially available varieties such as PM 1220, DPL 5690, DPL 5415, and DPL 50 with glyphosate tolerance had similar stand count, height, and dry weight data when compared to the conventional varieties from the same lineage group regardless of a glyphosate application. When differences did occur, no consistent trends could be determined within these four lineage groups.

Hybrid modeling and dynamic simulation of automated batch plants

A proposal is presented for the hybrid modeling and dynamic simulation of automated batch processing plants with dominant discrete-event behavior. The proposal encompasses current techniques for modeling continuous-time/discrete-event processes, synthesizing discrete-event controllers as well as the use of industrial standards for batch control. The result is a hierarchical-modular model of a plant in which process and control tasks are clearly differentiated. Implementation rules are established for a specific dynamic simulator capable of handling hybrid systems. The approach is demonstrated by building and verifying a complete model for an automated milk pasteurization plant. Results show that handling problems of realistic complexity is feasible using state-of-the-art technology.

PCR identification of dermatophyte fungi Trichophyton rubrum, T. soudanense and T. gourvilii

Diagnosis of dermatophytosis employing conventional laboratory procedures has been complicated by the slow growth and varied morphological features shown by dermatophytes. After analysis of the nucleotide base sequences of a 1.2-kb fragment amplified from a dermatophyte fungus Trichophyton rubrum by arbitrarily primed PCR with random primer OPD18, a pair of primers (TRIF and TR1R) was designed and evaluated for specific identification of T. rubrum. The sensitivity of the primers TR1F and TR1R was high, as a specific PCR band of c. 600 bp was detected from as little as 7 pg of T. rubrum DNA. By examining 92 dermatophyte strains and clinical isolates, it was found that this pair of primers reacted in PCR with T. rubrum, T. soudanense and T. gourvilii through formation of the specific fragment of 600 bp, but not with any other of the dermatophyte species or varieties, fungi, yeasts or bacteria tested. As T rubrum is one of the most frequently isolated dermatophyte fungi, and T. soudanense and T. gourvilii are relatively uncommon in many parts of the world, these primers can be used for rapid, sensitive and specific identification and differentiation of T. rubrum from other fungi and micro-organisms.

Organs/systems potentially involved in one model of programmed hypertension in sheep

1. When pregnant ewes and their fetuses are exposed to the synthetic glucocorticoid dexamethasone for 2 days early in pregnancy (days 26-28; term 145-150 days), female offspring have increased blood pressure relative to a control group. In one series, this was shown to be due to increased cardiac output, concomitant with a reset mean arterial pressure/heart rate reflex. The first group of such animals had, by the age of 7 years, left ventricular hypertrophy and reduced cardiac functional capacity. 2. The elevation in blood pressure is not maintained by any change in the peripheral renin-angiotensin system (RAS). 3. There is, however, preliminary evidence that some aspects of local RAS (particularly in the kidney and brain) could have participated in the 'programming' event. The levels of mRNA for angiotensin II receptors (AT1, AT2) and angiotensinogen are increased in the kidney of such dexamethasone-treated fetuses in late gestation (130 days), some 100 days after steroid treatment. Similar increases in AT1 mRNA in the medulla oblongata of the fetal brain and large increases of mRNA for angiotensinogen occur in the hypothalamus. 4. These findings, together with evidence from the literature, suggest that both the kidney and parts of the brain are affected by events that also 'program' high blood pressure in the offspring of animals in which the intra-uterine environment has been perturbed at some stage.

A specific PCR assay for the dermatophyte fungus Microsporum canis

A DNA fragment of approximately 1.2 kb, generated from the common dermatophyte Microsporum canis by arbitrarily primed polymerase chain reaction (PCR) using random primer OPU13, was cloned and sequenced. Based on the resulting sequencing data, a forward primer (MC1F) and a reverse primer (MC1R) have been designed and assessed by PCR for their usefulness in the improved identification of M. canis. The results obtained suggest that these primers are specific for M. canis, as a band of 900 bp was amplified in PCR with genomic DNA from M. canis only, and not from any of the other dermatophyte species or varieties, other fungi or common bacteria examined. Combining this PCR technique with a rapid mini-preparation method for fungal DNA, a definitive diagnosis of M. canis can be achieved within a day from the primary cultures. Future refinement of a DNA purification protocol from clinical specimens would further enhance the potential of the PCR based test for improved detection and identification of M. canis.

Functional glucocorticoid receptors in the mesonephros of the ovine fetus

BACKGROUND

At 27 days of gestation in the ovine fetus (term = 145 to 150 days), the only kidney is the mesonephros, and allantoic fluid represents fetal urine. The hypothesis tested in this study was that functional glucocorticoid receptors (GRs) are present in this early mesonephric kidney.

METHODS

Pregnant ewes, between 26 and 30 days, were infused with saline, dexamethasone (0.48 mg/hour), cortisol (5 mg/hour), or aldosterone (10 microg/hour) for 48 hours and were then killed for collection of fetuses and fetal fluids. GR mRNA was measured by real-time polymerase chain reaction in whole fetuses, and the location of gene expression was determined by hybridization histochemistry.

RESULTS

Significant changes in allantoic fluid composition were produced by the exposure of the fetus to maternally infused synthetic (dexamethasone) and natural (cortisol) glucocorticoids, over a period of two days, compared with fetuses of ewes infused with vehicle (isotonic saline; N = 8) or aldosterone (N = 8). Volume of fluid was unchanged by any treatment, but both dexamethasone (N = 10) and cortisol (N = 8) caused significant (P < 0.05) decreases in sodium and chloride concentrations and increases in concentrations of potassium, urea, glucose, and fructose. GR mRNA was detected in equivalent concentrations in the whole fetuses of saline, dexamethasone, and cortisol treatments. The GR mRNA levels were significantly decreased in the aldosterone group. By hybridization histochemistry, GR mRNA was detected in most of the tubular cells of the mesonephros.

CONCLUSION

These results suggest that functional GRs are present in the early ovine mesonephros.

First Report of Rhizoctonia solani AG-7 on Cotton in Mississippi

During a field study of the soilborne mycobiota on cotton (Gossypium hirsutum L.) roots, Rhizoctonia solani Kühn AG-7 was isolated from dark brown lesions present on the tap, feeder, and secondary roots onto potato-dextrose agar (PDA) (34 g of medium per liter of distilled water). Isolate identification was confirmed using tester R. solani AG-7 isolates (Carling, University of Alaska) for comparison during anastomosis pairing. To confirm pathogenicity, six AG-7 isolates (65, 66, 67, 68, 69, 70) obtained from cotton roots were tested in a plant growth incubator (18-24°C) by mixing 2.5 ml of 2-week-old cornmeal sand inoculum (3 g cornmeal, 100 g sand, and 20 ml distilled water) with 500 ml of autoclaved soil into each of five replicate polystyrene pots (15 cm wide × 20 cm long) per isolate. Five control pots containing noninfested soil were added for comparison. Five seed of cv. Deltapine 50 were sown into each pot. For all six isolates, mean stand counts (ranging from 0 and 1.3 plants per pot) were significantly lower (P ≤ 0.05) compared with those of plants in noninfested pots (3.8 plants per pot) at 21 days after planting. Furthermore, when the roots of surviving seedlings were evaluated for disease severity, brown, discolored lesions were observed at the base of stems and on roots in infested pots for all six isolates. Six AG-7 cultures of the pathogen were reisolated from symptomatic tissues onto PDA. The experiment was repeated with similar results. This is the first report of AG-7 occurring in Mississippi.

Application of PCR to the identification of dermatophyte fungi

Infection of the keratinised tissues (skin, hair and nails) in man and animals by keratinophilic fungi (dermatophytes) results in dermatophytosis (also known as tinea or ringworm). As conventional laboratory procedures for the identification of dermatophytes are either slow or lack specificity, improved diagnostic methods are required. The application of nucleic acid amplification technology has made rapid and precise identification of dermatophytes possible. Recent studies have shown that when one of the four random primers (OPAA11, OPD18, OPAA17 and OPU15) was used in arbitrarily primed PCR (AP-PCR), up to 20 of the 25 dermatophyte species or subspecies under investigation could be distinguished on the basis of characteristic band patterns detected in agarose gel electrophoresis. A combination of two random primers (OPD18 and OPAA17) used in separate reaction tubes identified 23 of the 25 dermatophyte species or subspecies examined. AP-PCR provides a rapid and practical tool for identification of dermatophyte isolates that is independent of morphological and biochemical characteristics and thus enhances laboratory diagnosis of dermatophytosis.

Ontogeny of aquaporins 1 and 3 in ovine placenta and fetal membranes

A sensitive and highly reproducible method has been used to show that Aquaporin 3 (AQP(3)) mRNA is present in the ovine placenta and chorion from at least 60 days of gestation (term=145-150d) with levels increasing substantially (>16 fold) at 100 days, and remaining constant thereafter. By immuno- and hybridization histochemistry, the epithelial cells expressing AQP(3)were found to be the trophoblast cells. Some AQP(3)was expressed in fibroblasts of the amnion and allantois but none was expressed in the epithelia of these membranes. AQP(1)was expressed in endothelial cells of fetal and maternal blood vessels but not in any epithelial cell of the ovine placenta and fetal membranes. The level of AQP(3)expression is consistent with known ovine placental permeabilities to water, glycerol and urea.

Ontogeny and regulation of the AT1 and AT2 receptors in the ovine fetal adrenal gland

The expression and regulation of the receptors for angiotensin II (both AT1 and AT2) were examined in the ovine fetal adrenal gland by RNase protection assay (RPA), in situ hybridisation histochemistry, immunohistochemistry and Western blotting. Both mRNA and protein for the AT1 receptor were present in the zona glomerulosa and zona fasciculata of the cortex, but not in the medulla, from as early as these zonas were distinguishable (60 days of gestation; term is 145-150 days), and even present in the steroidogenic cells of the unzoned gland at 40 days. The mRNA for the AT2 receptor was present in the same locations (but never in the medulla) from 40-130 days, and declined to extremely low levels after 140 days. The infusion of ang II, 1 microg/h, for 3 days, at mid-gestation (76 +/- 2 days) caused a significant decrease in mRNA for AT1 but no change in AT2 levels. Thus, the biologically active receptor (in terms of aldosterone stimulation) is present in the ovine fetal adrenal from very early in development, and can be down-regulated by mid-gestation.