A real-time PCR assay for detection and quantification of Verticillium dahliae in spinach seed

Verticillium dahliae is a soilborne fungus that causes Verticillium wilt on multiple crops in central coastal California. Although spinach crops grown in this region for fresh and processing commercial production do not display Verticillium wilt symptoms, spinach seeds produced in the United States or Europe are commonly infected with V. dahliae. Planting of the infected seed increases the soil inoculum density and may introduce exotic strains that contribute to Verticillium wilt epidemics on lettuce and other crops grown in rotation with spinach. A sensitive, rapid, and reliable method for quantification of V. dahliae in spinach seed may help identify highly infected lots, curtail their planting, and minimize the spread of exotic strains via spinach seed. In this study, a quantitative real-time polymerase chain reaction (qPCR) assay was optimized and employed for detection and quantification of V. dahliae in spinach germplasm and 15 commercial spinach seed lots. The assay used a previously reported V. dahliae-specific primer pair (VertBt-F and VertBt-R) and an analytical mill for grinding tough spinach seed for DNA extraction. The assay enabled reliable quantification of V. dahliae in spinach seed, with a sensitivity limit of ≈1 infected seed per 100 (1.3% infection in a seed lot). The quantification was highly reproducible between replicate samples of a seed lot and in different real-time PCR instruments. When tested on commercial seed lots, a pathogen DNA content corresponding to a quantification cycle value of ≥31 corresponded with a percent seed infection of ≤1.3%. The assay is useful in qualitatively assessing seed lots for V. dahliae infection levels, and the results of the assay can be helpful to guide decisions on whether to apply seed treatments.     

Surgical sterilization of free-ranging wolves

The objective of the study was to determine whether surgical sterilization of both males and females in wolf pairs alters basic wolf social and territorial behaviors. Wolves were located from the air by snow-tracking methods and were tranquilizer-darted from a helicopter. Surgeries were performed either in a tent at the capture site or in a heated building in a nearby village. Six vasectomies and seven uterine horn ligations were performed in January and February of 1996 and 1997. Two females died: one likely related to the capture procedure, the other of a peritonitis unrelated to the surgery. One wolf had a litter. None of the wolves have shown changes in behavioral patterns. Surgical sterilization can be effective, but other, less invasive, fertility control techniques should be investigated.     

Genetic parameters of lifetime performance traits in Holstein cows

SUMMARY: Heritabilities, genetic and phenotypic correlations among lifetime yields of milk, fat and protein, herdlife, productive life and number of lactations initiated in the herd were estimated from records of 44,933 progeny of 427 young and 119 proven Holstein sires in 1949 herds using a multivariate Reml technique to fit a sire model with relationships among young sires. Proven sires were fitted as fixed effects. Heritabilities of lifetime traits ranged from 0.005 to 0.030, suggesting little scope for direct selection for lifetime performance traits. Productive life had highest genetic correlation with lifetime fat yield (0.934), but correlations with lifetime milk and protein yields were smaller and similar (0.773 and 0.772). The number of lactations also had highest genetic correlation with lifetime fat yield. ZUSAMMENFASSUNG: Genetische Parameter von Lebensleistungsmerkmalen bei Holsteinkühen Heritabilit?tswerte, genetische und ph?notypische Korrelationen zwischen Lebensleistungsmerkmalen für Milch, Fett und Protein, Lebensdauer, produktive Zeit und Zahl Laktationen wurden won 44933 Nachkommen von 427 jungen und 119 nachkommenschaftsgeprüften Holsteinstieren in 1949 Herden mittels einer multivariablen REML-Technik gesch?tzt, die auf einem Vatertiermodell mit Verwandtschaft zwischen den jungen Stieren beruhte. Geprüfte Stiere wurden als fixe Effekte im Modell berücksichtigt. Heritabilit?tswerte dieser Merkmale rangieren von 0.005 bis 0.03, so da? wenig Aussichten für Erfolg direkter Selektion auf Lebensleistungsmerkmale besteht. Die L?nge des produktiven Lebens hatte die h?chste genetische Korrelation mit Lebensfettmenge (0.934), aber die Korrelationen mit Milch- und Protein-Lebensleistung waren kleiner und ?hnlich (0.773 und 0.772). Die Zahl der Laktationen hatte die h?chste genetische Korrelation mit der Lebensfettmenge.     

Relationships of first lactation yields with lifetime performance traits in Holstein cows

SUMMARY: Genetic and phenotypic correlations between the first lactation and lifetime yields of milk, fat and protein, herdlife, productive life and number of lactations initiated in the herd were estimated from records of 24,231 progeny of 234 young and 119 proven Holstein sires in 1791 herds using a multivariate REML technique to fit a sire model with relationships among young sires. Proven sires were fitted as fixed effects. Genetic correlations between first lactation and lifetime yields were highest for milk (0.666) followed by fat (0.660) and protein (0.512). Genetic as well as phenotypic correlations of herdlife, productive life and number of lactations were higher with first lactation milk yield than with first lactation fat and protein yields. Direct selection for higher lifetime yields would not be effective because of low heritabilities. However the high, positive genetic correlations of lifetime yields of milk and fat with first lactation yields suggested that first lactation yields might be used for indirect selection for higher lifetime yields. ZUSAMMENFASSUNG: Beziehung zwischen Erstlaktations- und Lebensleistung bei Holstein-Kühen Zwischen Erstlaktations- und Lebensleistung für Milch, Fett, Protein, Verbleibedauer, produktiver Lebensdauer und Zahl von Laktationen in der Herde wurden von 24.291 T?chtern, 234 Jung- und 119 geprüften Holsteintieren in 1.791 Herden genetische Beziehungen gesch?tzt, wobei eine multivariate REML-Technik zur Analyse eines Stiermodells mit Verwandtschaft zwischen jungen Stieren angewendet worden ist. Die geprüften Stiere wurden als fixe Effekte angesehen. Genetische Korrelationen zwischen Erstlaktation und Lebensleistung war am h?chsten für Milch (0,666), gefolgt von Fett (0,660) und Protein (0,512). Genetische und ph?notypische Korrelationen mit Verbleibedauer, produktiver Lebensdauer und Zahl der Laktationen waren ebenfalls für Erstlaktations-milchmenge h?her als bei Fett und Protein. Direkte Selektion auf h?here Lebensleistung würde wegen der niedrigen Heritabilit?t nicht wirksam sein. Allerdings k?nnten die hohen positiven genetischen Korrelationen des Merkmals mit Erstlaktationsleistungen diese als geeignetes indirektes Selektionskriterium für h?here Lebensleistung anzeigen.     

Analyzing a forest conversion history database to explore the spatial and temporal characteristics of land cover change in Guatemala's Maya Biosphere Reserve

We analyzed forest clearing and regrowth over a 23-year time period for 21 forest concession and management units within the Maya Biosphere Reserve(MBR), Guatemala. The study area as a whole experienced a clearing rate of0.16%/year from 1974 through 1997. The overall clearing rate appears rather low when averaged over the entire study area over 23 years because most of the reserve was inaccessible. However, despite the granting of legal protection to the MBR in 1990, clearing rates continued to rise, with the highest rates occurring in the most recent time period in the analysis, 1995 to1997. Higher rates of clearing relative to regrowth occurred in newly established communities and in the Reserve's buffer zone, where the clearing of high forest was preferred for pasture development. Exploratory models were built and analyzed to examine the effects of various landscape variables on forest clearing. The different units in the analysis showed different relationships of forest clearing with variables such as forest cover type and distance to access(roads and river corridors). Where available, socio-economic household survey data helped to explain patterns and trends observed in the time series Landsat imagery. A strong relationship between forest clearing and distance to access was demonstrated. More clearing occurred further from roads during later time periods as farmers moved deeper into the forest to find land to clear. Communities inside the MBR that were less dependent on farming had forest clearing to regrowth ratios of one:one or less. These communities used fallow fields in greater proportions than communities in the Reserve's buffer zone. General trends in clearing by forest cover type suggest a preference for clearing high forest (bosque alto) types found on the higher elevation, better-drained soils, and fallow fields,and an avoidance of low-lying, seasonally flooded terrain(bajos). Satellite remote sensing observations of forest clearing and regrowth patterns can provide an objective source of information to complement socio-economic studies of the human driving forces in land cover and land use change. This revised version was published online in July 2006 with corrections to the Cover Date.     

B-cell lymphoma in the peripheral nerves of a cat

A B-cell, Burkitt-type lymphoma, diffusely affecting the peripheral nerves and intramuscular nerve branches was diagnosed in a 4-year-old domestic shorthair cat with a chronic progressive history of flaccid tetraparesis and generalized muscle atrophy. There was no evidence of cranial nerve, central nervous system, radicular, bone marrow, splenic, or lymph node involvement. The cat tested negative for feline retroviruses and a wide variety of herpes viruses, including Epstein-Barr virus. The clinical manifestation of this case was similar to the chronic polyneuropathic variant of human diffuse neurolymphomatosis; a condition most commonly caused by an axonopathy resulting from infiltration of peripheral nerves with non-Hodgkin's lymphoma.     

Technical note: prediction of breeding values using marker-derived relationship matrices

In livestock populations, estimation of breeding values for selection requires a matrix describing the additive relationship between individuals in the population. This matrix can be derived from pedigree information. In some livestock populations, pedigree information may be unavailable, incomplete, or in error. Here we use simulated data to demonstrate that marker-derived relationship matrices can be used to predict breeding values and estimate additive variance components, provided the markers are sufficiently dense. The approach is demonstrated for an Angus data set with 9,323 SNP markers genotyped.