Identification of a RAPD marker linked to a brown planthopper resistance gene in rice

We report the tagging of a brown planthopper (BPH) resistance gene (Bph–1) in rice using RAPD and RFLP markers. The Korean rice variety ‘Gayabyeo’ has dominant duplicate genes including Bph–1 conferring resistance to biotype 1 of BPH. Bulked segregant RAPD analysis was employed for rapid identification of DNA markers linked to resistance genes. For tagging these two genes, an F2F3 population from a ‘Gayabyeo’ × ‘Nagdongbyeo’ cross was developed and evaluated for BPH resistance. Three bulked DNAs from two groups of homozygous BPH resistant (each for Bph–1 and the other unknown gene) and homozygous susceptible F2 plants were analyzed by RAPD using 140 random oligomers. One primer, OPD–7 yielded a 700-bp fragment that was present in Gayabyeo and resistant F2 plants (homozygous for Bph-1 locus) but absent in Nagdongbyeo and susceptible F2 plants. Cosegregation of this marker with Bph-1 was verified using an F2 population segregating for Bph-1. Chromosomal regions surrounding the Bph-1 were examined with additional RFLP and microsatellite markers on chromosome 12 to define the location of the RAPD marker and Bph-1. Use of this RAPD marker could facilitate early selection of resistant lines for BPH. This revised version was published online in July 2006 with corrections to the Cover Date.     

Occupancy pattern of a long-horned beetle in a variegated forest landscape: linkages between tree quality and forest cover across spatial scales

Context

Interactions between landscape-scale processes and fine-grained habitat heterogeneity are usually invoked to explain species occupancy in fragmented landscapes. In variegated landscapes, however, organisms face continuous variation in micro-habitat features, which makes necessary to consider ecologically meaningful estimates of habitat quality at different spatial scales.

Objectives

We evaluated the spatial scales at which forest cover and tree quality make the greatest contribution to the occupancy of the long-horned beetle Microplophorus magellanicus (Coleoptera: Cerambycidae) in a variegated forest landscape.

Methods

We used averaged data of tree quality (as derived from remote sensing estimates of the decay stage of single trees) and spatially independent pheromone-baited traps to model the occurrence probability as a function of multiple cross-scale combinations between forest cover and tree quality (with scales ranging between 50 and 400 m).

Results

Model support and performance increased monotonically with the increasing scale at which tree quality was measured. Forest cover was not significant, and did not exhibit scale-specific effects on the occurrence probability of M. magellanicus. The interactive effect between tree quality and forest cover was stronger than the independent (additive) effects of tree quality and particularly forest cover. Significant interactions included tree quality measured at spatial scales ≥200 m, but cross-scale interactions occurred only in four of the seven best-supported models.

Conclusions

M. magellanicus respond to the high-quality trees available in the landscape rather than to the amount of forest per se. Conservation of viable metapopulations of M. magellanicus should consider the quality of trees at spatial scales >200 m.

     

Molecular characterization and in planta detection of Fusarium moniliforme endopolygalacturonase isoforms

The activation of Fusarium moniliforme endopolygalacturonase (endoPG) was studied during infection of maize plants. EndoPG is a plant cell wall degrading enzyme that cleaves the pectin component causing cell death. The authors generated several hybridoma cell lines producing endoPG specific monoclonal antibodies. One monoclonal antibody was selected and successfully used in Western blotting analysis to detect F. moniliforme endoPG secretion in vitro and in planta. Two F. moniliforme strains (FC-l0 and 62264) were used for the studies. Both strains revealed the expression of a single endoPG in vitro as in planta. EndoPG from strain FC-10 presented four isoforms whereas only two isoforms were revealed in the endoPG from strain 62264. Differences were also found in the sequences of the two endoPG genes indicating the presence of endoPG variability among F. moniliforme strains.     

Treatment of dogs with oral melanoma by hypofractionated radiation therapy and platinum-based chemotherapy (1987-1997)

This retrospective study in 39 dogs with incompletely resected oral melanoma examined the efficacy of hypofractionated radiation therapy and platinum-containing chemotherapy. All dogs were completely staged, with the majority of dogs classified as stage 1. Dogs received 6 weekly fractions of 6-gray (Gy) megavoltage irradiation with a cobalt-60 unit or a 4-MeV (megaelectron volts) linear accelerator. Dogs received cisplatin (10-30 mg/m2 IV) or carboplatin (90 mg/m2 IV) chemotherapy 60 minutes before radiation delivery. Durations of local control, metastasis-free survival time, and overall survival time were recorded. By the Kaplan-Meier method, 15% of the dogs had local recurrence within a median time of 139 days. Fifty-one percent of the dogs developed metastatic disease within a median time of 311 days (range, 24-2, 163 days). Median survival time for all 39 dogs was 363 days. The combined use of chemotherapy and radiation therapy in this protocol provided local control consistent with previous studies. Low-dose chemotherapy was used with the intent of enhancing radiation therapy for the local control of an incompletely excised tumor. Survival times were longer than previously reported for dogs with oral malignant melanoma. Additional studies are required to determine whether these results were due to the effects of chemotherapy on microscopic disease or the enhanced local control provided by chemoradiation therapy.     

Measurement of the Lateral Thoracic Reflex Latency in Ponies

Lateral thoracic nerve reflex latencies values were measured in ponies using a simple, non-invasive technique. The reflex was elicited using an external triggering hammer attached to an electrodiagnostic unit. The resulting evoked, compound muscle action potentials were recorded with electrodes, which were placed over the 6th ribs or 11th rib level with the axilla. Two superimposed repeats of 4 signal-averaged sweeps of 50 or 100 milliseconds were recorded and the estimated reflex pathway was measured for each subject in order to calculate the reflex latencies and latency velocities. Mean left and right 6th rib peak latencies were not significantly different from each other ( P = .609), but left 6th rib latencies were shorter than those recorded from the 11th rib ( P < .0001), substantiating the existence of an indirect (central) pathway to the reflex. The calculated left and right 6th rib latency velocities were not significantly different from each other ( P = .58) but left 6th rib latency velocities were different from left 11th rib ( P = .009). The calculated latency velocities were within the broad range for corticospinal tract motor conduction velocities and comparable to magnetic motor evoked latency velocities. The use of lateral thoracic reflex latency measurements to objectively identify the site of spinal cord lesions is discussed.     

Development of a multiplex loop-mediated isothermal amplification assay to detect shiga toxin-producing Escherichia coli in cattle

A multiplex loop-mediated isothermal amplification (mLAMP) assay was developed for simultaneous detection of the stx1 and stx2 genes and applied for detection of shiga toxin-producing Escherichia coli (STEC) in cattle farm samples. Two target genes were distinguished based on T_m values of 85.03 ± 0.54℃ for stx1 and 87.47 ± 0.35℃ for stx2. The mLAMP assay was specific (100% inclusivity and exclusivity), sensitive (with a detection limit as low as 10 fg/µL), and quantifiable (R² = 0.9313). The efficacy and sensitivity were measured to evaluate applicability of the mLAMP assay to cattle farm samples. A total of 12 (12/253; 4.7%) and 17 (17/253; 6.7%) STEC O157, and 11 (11/236; 4.7%) non-O157 STEC strains were isolated from cattle farm samples by conventional selective culture, immunomagnetic separation, and PCR-based culture methods, respectively. The coinciding multiplex PCR and mLAMP results for the types of shiga toxin revealed the value of the mLAMP assay in terms of accuracy and rapidity for characterizing shiga toxin genes. Furthermore, the high detection rate of specific genes from enrichment broth samples indicates the potential utility of this assay as a screening method for detecting STEC in cattle farm samples.     

Single-phase methylene diphosphate bone scintigraphy in the diagnostic evaluation of dogs with osteosarcoma

In this study, 25 dogs each with a histopathologically diagnosed appendicular or axial osteosarcoma were prospectively and consecutively examined by methylene diphosphate nuclear scintigraphy. Scannings that revealed scintigraphically enhanced focal increased activity via bone uptake of the 99mTc methylene diphosphate radionuclide at sites other than the primary tumor site were compared with scintigrams obtained from dogs without osteosarcoma. Secondary scintigraphic sites were evaluated by survey radiography and, if possible, by histologic examination (biopsy or necropsy specimens). On the basis of our findings, scintigraphy seems to be more efficient than physical examination and radiographic bone survey for the diagnosis of multicentric, metachronous, or metastatic canine osteosarcoma.     

Feeding patterns in five predatory fishes of the high Paranà River floodplain (PR, Brazil)

Abstract— Between March 1992 and February 1993 five piscivorous fish species, Acestrorhynchus lacustris (Reinhardt, 1874), Hoplias malabaricus (Bloch, 1794), Rhaphiodon vulpinus Agassiz, 1829, Salminus maxillosus , Valenciennes, 1840 and Plagioscion squamosissimus (Heckel, 1840), of the high Paranà River floodplain showed a wide total prey spectrum though only three to four taxa were dominant in their diet. Shrimp, Macrobrachium amazonicum , were also common to the majority of species. Seasonal and spatial variations occurred throughout the study period probably due the availability of prey species. The main resources shared by the predators were also the most abundant in the area, with consumption markedly focused on prey about 5.0 cm long. Detrended correspondence analysis was effective in discriminating two groups of predators species that exploited distinct microhabitats. The predators with the least scores consumed small characids that inhabit mid-water or the littoral region, whereas those with the largest scores consumed prey associated to the bottom.