Population structure of Solanum carolinense along the Takano River in Kyoto, Japan as determined by amplified fragment length polymorphism analysis

Areas infested with Solanum carolinense, an introduced perennial weed, have increased quickly in Japan. The genetic structure of a S. carolinense population along the Takano River in Kyoto, Japan was investigated using amplified fragment length polymorphism (AFLP) analysis to reveal how introductions and local spread have contributed to the development of this population. Along a terrace beside the river and an adjacent roadside, we defined a cluster of above‐ground shoots in the population as a subpopulation and 60 subpopulations were identified. Seventeen of these were selected and 165 shoots were analyzed by AFLP analysis using three primer pairs. The AFLP profiles revealed 69 genotypes and the presence of several clones, i.e. genotypes that were present in more than one individual. In total, 19 clones, comprising 2–34 identical genotypes, could be identified in the population. Each of these clones, except one, was allocated within each of the subpopulations. Clustering of the subpopulations was supported by high bootstrap values in all cases. Therefore, introductions from distant regions have mainly contributed to the development of this population, and local spread by seed or vegetative reproduction has rarely been important. The most likely introduction route of S. carolinense to this population was via planting associated with construction works.     

Magneto-opto-electronic bistability in a phenalenyl-based neutral radical

A new organic molecular conductor, based on a spiro-biphenalenyl neutral radical, simultaneously exhibits bistability in three physical channels: electrical, optical, and magnetic. In the paramagnetic state, the unpaired electrons are located in the exterior phenalenyl units of the dimer, whereas in the diamagnetic state the electrons migrate to the interior phenalenyl units and spin pair as a pi-dimer. Against all expectations, the conductivity increases by two orders of magnitude in the diamagnetic state, and the band gap decreases. This type of multifunctional material has the potential to be used as the basis for new types of electronic devices, where multiple physical channels are used for writing, reading, and transferring information.     

In vitro gas production measurements to evaluate interactions between untreated and chemically treated rice straws, grass hay, and mulberry leaves

In vitro gas production was measured to investigate associative effects of untreated and chemically treated rice straw (RS) and of RS and grass hay or mulberry leaves (ML). The RS was treated with NaOH, urea, or (NH4)HCO3. Cumulative gas production was recorded at 2, 4, 6, 8, 12, 16, 24, 36, 48, 60, 72, and 96 h of incubation, and the Gompertz function was used to describe the kinetics of gas production. Treatment with NaOH, urea, and NH4HCO3 increased (P < 0.05) gas production at 48 h by 55, 52, and 37% and the maximum rate of gas production of RS from 0.64 to 1.51, 1.27, and 1.13 mL/h, respectively. The inclusion of treated straws, hay, and ML in a mixture with RS at increasing proportions (25, 50, 75, 100%) elevated cumulative gas production and its rate. Maximum gas production was not different between the RS and its mixtures with the treated straws, but inclusion of hay into RS or NH4HCO3-treated RS increased the maximum gas production. Associative effects were defined as the difference between the observed gas production for the mixtures and the sum of the individual component feeds. The NaOH-treated RS, included at higher proportions, had positive associative effects at all times of incubation < 96 h; effects were negative or absent at 96 h. No effects were observed with mixtures of RS with urea-treated RS. The NH4HCO3-treated RS mixture tended to have negative associative effects at all three levels. Positive associative effects (P < 0.05) were observed for both RS and NH4HCO3-treated RS at almost all inclusion levels of hay or ML after 12 to 96 h of incubation. The response was more pronounced with ML than with hay. Associative effects generally declined with duration of incubation. We conclude that positive associative effects on in vitro gas production occurred more consistently when RS was incubated in mixtures with hay or ML than when incubated in mixtures with chemically treated RS.     

Heterozygosity for genes influencing a quantitative trait

Choosing families to sample for a quantitative trait locus mapping experiment is a critical component of experimental design because only heterozygous families contribute information to the analysis. Additive genetic variance of a paternal half-sib family can be partitioned into two parts: a variance component of maternal source that is constant across different families and a variance component of paternal source that is defined as an index of heterozygosity of a sire. This index is shown to be an upper limit of variance among marker genotypes of a half-sib family and can be used to identify highly heterozygous sires, thus improving the power of detecting QTL in detection studies. Simulated progeny phenotypic data were used to estimate sire's heterozygosity index via an ANOVA method, and accuracy of the estimation was evaluated with the correlation coefficient between the true and estimated index summarized both as the correlation and by the correct ranking of results as measured by the ratio of the true average heterozygosity index of experimentally selected parents to average heterozygosity of all sires. Positive but small correlation can be achieved in the estimation of a sire's heterozygosity when based on the daughters' phenotypic data, and accuracy was improved when progeny-tested sons were used to estimate their grandsire's heterozygosity index, depending on the genetic model of a trait and the size and structure of families.     

The effect of lean growth rate on puberty attainment in gilts

Two hundred sixteen prepubertal Genex Manor hybrid F1 gilts were used to determine the impact of lean growth rate on sexual development of gilts. This study was composed of two experiments (Exp. 1 and Exp. 2). In Exp. 1, at approximately 96 d of age and 54 kg weight, gilts were allocated with respect to growth rate and litter origin to one of two dietary treatments: 1) a diet formulated to maximize lean growth potential (LP; n = 84) or 2) a diet formulated to produce a lower lean growth rate (LL; n = 84). In Exp. 2, at approximately 88 d of age and 50 kg weight, gilts were allocated with respect to growth rate and litter origin to one of two dietary treatments: 1) a diet formulated to maximize lean growth potential (LP; n = 24) or 2) a diet formulated to restrict lean growth further than was achieved in LL in Exp. 1 (RL; n = 24). All gilts were fed treatment diets for ad libitum consumption and housed in groups of six. Weight, backfat depth and loin depth, and feed intake were measured weekly. Starting at 135 d of age, gilts received 20 min of direct daily exposure to a boar as a pen group for pubertal stimulation. Puberty attainment was determined as the day gilts first exhibited the standing reflex in response to contact with a boar. At pubertal estrus, body weight, backfat depth, and loin depths were recorded. Diet affected (P < or = 0.05) estimated fat-free lean gain (LP, 424 vs LL, 347 g/d, Exp. 1; LP, 397 vs RL, 376 g/d, Exp. 2) during the growth period (start to stimulation). However, age at puberty was not affected by diet (LP, 157.3 vs LL, 157.6, Exp. 1; LP, 166.7 vs RL, 167.3, Exp. 2) or overall lean growth at stimulation (P > or = 0.05 in both experiments), confirming that innate variability in sexual development of commercial genotypes, rather than growth performance, determines onset of sexual maturity. A negative correlation between age at puberty and growth rate from 50 kg until puberty (P < or = 0.05) (LP, r = -0.40, LL, r = -0.36, Exp. 1; LP, r = -0.64, RL, r = -0.48, Exp. 2) was a consequence of reduced lean tissue growth during the stimulation period in later-maturing gilts.     

Order of amino acid limitation in poultry by-product meal

1. Two chick assays (from 8 to 17 d posthatching) were conducted to determine the order of amino acid (AA) limitation in poultry by-product meal (PBPM) using AA deletion and addition assays. 2. In the deletion assay, the basal diet contained 155 g/kg crude protein (provided solely by PBPM) and was fortified with cystine, tryptophan, threonine, lysine, valine, isoleucine, histidine, methionine and phenylalanine to meet the Illinois ideal AA Pattern. Each AA was then deleted individually from the basal diet and its effect on growth assessed. 3. In the addition assay, various individual or combined additions of nine AAs were made to an unfortified 155 g/kg crude protein diet containing PBPM as the sole source of dietary crude protein. 4. The results from the deletion assay were in general agreement with those from the addition assay. Based on the combined results of the deletion and addition assays, the order of AA limitation in PBPM was 1) cystine, 2) tryptophan, 3) threonine and lysine, 5) valine, and 6) isoleucine and histidine with the degree of deficiency of valine, isoleucine and histidine being similar. The results also suggested that methionine may be slightly limiting in PBPM protein.     

Rhabdomyosarcoma of the tongue in a dog

A lingual rhabdomyosarcoma was diagnosed in a six-year-old Staffordshire bull terrier with clinical signs of dysphagia. The unsuccessful response to initial chemotherapy, to surgical resection and subsequent surgical resection and radiation therapy is documented. The accurate diagnosis and prognosis of such tumours is also discussed. Lingual rhabdomarcoma has not previously been reported in the dog.     

Effects of initial epidemic conditions, sporulation rate, and spore dispersal gradient on the spatio-temporal dynamics of plant disease epidemics

ABSTRACT A stochastic model that simulates the spread of disease over space and time was developed to study the effects of initial epidemic conditions (number of initial inocula and their spatial pattern), sporulation rate, and spore dispersal gradient on the spatio-temporal dynamics of plant disease epidemics. The spatial spread of disease was simulated using a half-Cauchy distribution with median dispersal distance mu (units of distance). The rate of temporal increase in disease incidence (beta(I), per day) was influenced jointly by mu and by the sporulation rate lambda (spores per lesion per day). The relationship between beta(I) and mu was nonlinear: the increase in beta(I) with increasing mu was greatest when mu was small (i.e., when the dispersal gradient was steep). The rate of temporal increase in disease severity of diseased plants (beta(S)) was affected mainly by lambda: beta(S) increased directly with increasing lambda. Intraclass correlation (kappa(t)), the correlation of disease status of plants within quadrats, increased initially with disease incidence, reached a peak, and then declined as disease incidence approached 1.0. This relationship was well described by a power-law model that is consistent with the binary form of the variance power law. The amplitude of the model relating kappa(t) to disease incidence was affected mainly by mu: kappa(t) decreased with increasing mu. The shape of the curve was affected mainly by initial conditions, especially the spatial pattern of the initial inocula. Generally, the relationship of spatial autocorrelation (rho(t,k)), the correlation of disease status of plants at various distances apart, to disease incidence and distance was well described by a four-parameter power-law model. rho(t,k) increased with disease incidence to a maximum and then declined at higher values of disease incidence, in agreement with a power-law relationship. The amplitude of rho(t,k) was determined mainly by initial conditions and by mu: rho(t,k) decreased with increasing mu and was lower for regular patterns of initial inocula. The shape of the rho(t,k) curve was affected mainly by initial conditions, especially the spatial pattern of the initial inocula. At any level of disease incidence, autocorrelation declined exponentially with spatial lag; the degree of this decline was determined mainly by mu: it was steeper with decreasing mu.     

Factors affecting the incubation period of dark leaf and pod spot (Alternaria brassicae) on oilseed rape (Brassica napus)

Experiments to investigate the factors affecting the incubation period of dark leaf and pod spot (Alternaria brassicae) on leaves and pods of oilseed rape (Brassica napus) were done in controlled environment (constant temperatures) and glasshouse conditions (fluctuating temperatures). The length of the incubation period of dark leaf and pod spot decreased as infection and incubation temperatures increased from 6 to 20 °C. The incubation period decreased as wetness period increased from 2 to 12 h, as inoculum concentration increased from 80 to 2 × 10³ spores ml^–1 and as leaf age increased from 4 to 10 days. Asymptotes of leaf age and inoculum concentration, above which the length of the incubation period did not decrease, were 10 days and 2 × 10³ spores ml^–1, respectively. The shortest and longest incubation periods were 1 and 11 days. The mechanism by which the infection conditions influenced the incubation period of dark leaf and pod spot on oilseed rape seemed to be linked to lesion density. Usually, the length of the incubation period decreased greatly with increasing lesion density.