Distribution and multiplication of Ralstonia solanacearum strain race 1 biovar 4 in vegetable sweet potato cuttings

Ralstonia solanacearum (RS) race 1 biovar 4 (R1bv4), causal agent of bacterial wilt in vegetable sweet potato (VSP), is often latent in VSP vines and is important in introduction of the pathogen to newly planted fields. In this study, the effects of biological and environmental factors on the distribution and multiplication of R1bv4 in VSP tissues were examined. Based on stem-injection inoculation, the R1bv4strain of NC01 could cause 49.0% and 33.0% wilting on VSP cultivars TN71 and WS, respectively. The populations of NC01 in diseased TN71 and WS were 10⁸–10⁹ cfu/g tissue at 28th day after inoculation. On the other hand, the R1bv4 could not cause symptom in cultivars of TN57 and VSPSL-1 vine and the NC01 was confined to near the injection sites. Temperature tests indicated that NC01 could cause 28.0% and 14.0% wilting on cultivar TN71 at 28 and 20°C, respectively. Moreover, the populations of NC01in diseased plants were 1.6 × 10⁹ and 7.9 × 10⁸ cfu/g tissue at 28 and 20°C, respectively. The distribution of NC01 in VSP stem indicated that the isolation frequency of NC01 was lower than 31.0% in terminal shoots or erect stems and 45.0 to 100.0% in creeping stem after 8 wks planted in infested soil (10⁶ cfu/g soil). The results demonstrated that terminal shoots or erect stems were not common carrier for transmitting R1bv4. Furthermore, two R1bv4 strains, NC01 and HsinT01, were examined the ability for latent infection on cv. TN71. The results revealed that NC01 and HsinT01 showed different ability of latent infection on cultivar TN71. NC01 had lower percentage (46.8% and 45.1%) than HsinT01 (93.4% and 75.3%) at 20 and 28°C.     

Identification and partial characterization of a latent ATP,Mg-dependent protein phosphatase in rabbit skeletal muscle cytosol

Summary Fractionation of rabbit skeletal muscle cytosol on Aminohexyl-Sepharose has resulted in the identification of a latent ATP, Mg-dependent protein phosphatase whose catalytic subunit is in the active conformation, but is inhibited by the presence of more than one modulator unit. The partially purified enzyme is converted to an inactive, kinase F_A-dependent form upon incubation at 30°C unless modulator-specific polyclonal antibodies are added to the preparation. The immunoglobulins also relieve the inhibition which is responsible for the low basal phosphatase activity of the enzyme, and they counteract all of the heat-stable inhibitor activity present in the preparation. Addition of free catalytic subunit abolishes the inhibition of the latent enzyme in a dose-dependent way, but cannot prevent the inactivation process. The inactivated phosphatase and the original latent enzyme exhibit the same apparent M _r in sucrose density-gradient centrifugation (70 000) and in gel filtration (110 000).Abbreviations PMSF Phenylmethanesulphonyl Fluoride - TLCK L-l-chloro-3-(4-tosylamido)-7-amino2-heptanone-hydrochloride - TPCK L-l-chloro-3-(4-tosvlamido)-4-phenyl-2-butanone     

Ammoniacal silver staining of proteins: mechanism of glutaraldehyde enhancement

When the conditions for detecting proteins by ammoniacal silver staining (B. R. Oakley, D. R. Kirsch, and N. R. Morris (1980) Anal. Biochem. 105, 361-363.) following gel electrophoresis were varied, it was noted that glutaraldehyde pretreatment was necessary for maximal staining, which could not be explained simply as the result of "fixation." Further studies indicated that glutaraldehyde enhancement of protein staining with this silver reagent was probably due to oxidation of the aldehyde groups by silver ions, resulting in metallic silver depositions within the gel which act as nucleation sites for additional metallic silver localization in the protein bands upon the addition of formaldehyde developer. This proposed mechanism is consistent with the Tollen's reaction, as well as some aspects of the photographic process. Consistent with this notion, silver-staining intensities are directly related to mole percentage lysine of various standard proteins.     

Latent group detection in functional partially linear regression models

In this paper, we propose a functional partially linear regression model with latent group structures to accommodate the heterogeneous relationship between a scalar response and functional covariates. The proposed model is motivated by a salinity tolerance study of barley families, whose main objective is to detect salinity tolerant barley plants. Our model is flexible, allowing for heterogeneous functional coefficients while being efficient by pooling information within a group for estimation. We develop an algorithm in the spirit of the K-means clustering to identify latent groups of the subjects under study. We establish the consistency of the proposed estimator, derive the convergence rate and the asymptotic distribution, and develop inference procedures. We show by simulation studies that the proposed method has higher accuracy for recovering latent groups and for estimating the functional coefficients than existing methods. The analysis of the barley data shows that the proposed method can help identify groups of barley families with different salinity tolerant abilities.     

Integrating sample similarities into latent class analysis: a tree-structured shrinkage approach

This paper is concerned with using multivariate binary observations to estimate the probabilities of unobserved classes with scientific meanings. We focus on the setting where additional information about sample similarities is available and represented by a rooted weighted tree. Every leaf in the given tree contains multiple samples. Shorter distances over the tree between the leaves indicate a priori higher similarity in class probability vectors. We propose a novel data integrative extension to classical latent class models with tree-structured shrinkage. The proposed approach enables (1) borrowing of information across leaves, (2) estimating data-driven leaf groups with distinct vectors of class probabilities, and (3) individual-level probabilistic class assignment given the observed multivariate binary measurements. We derive and implement a scalable posterior inference algorithm in a variational Bayes framework. Extensive simulations show more accurate estimation of class probabilities than alternatives that suboptimally use the additional sample similarity information. A zoonotic infectious disease application is used to illustrate the proposed approach. The paper concludes by a brief discussion on model limitations and extensions.     

A latent class model to multiply impute missing treatment indicators in observational studies when inferences of the treatment effect are made using propensity score matching

Analysts often estimate treatment effects in observational studies using propensity score matching techniques. When there are missing covariate values, analysts can multiply impute the missing data to create m completed data sets. Analysts can then estimate propensity scores on each of the completed data sets, and use these to estimate treatment effects. However, there has been relatively little attention on developing imputation models to deal with the additional problem of missing treatment indicators, perhaps due to the consequences of generating implausible imputations. However, simply ignoring the missing treatment values, akin to a complete case analysis, could also lead to problems when estimating treatment effects. We propose a latent class model to multiply impute missing treatment indicators. We illustrate its performance through simulations and with data taken from a study on determinants of children's cognitive development. This approach is seen to obtain treatment effect estimates closer to the true treatment effect than when employing conventional imputation procedures as well as compared to a complete case analysis.     

Further properties of wineberry latent virus and evidence for its possible involvement in calico disease

The flexuous filamentous particles of wineberry latent virus (WLV) were found to measure 620. 12 nm and not 510. 12 nm as previously reported. Analysis of dsRNA from infected plants detected a major species of c. 5.7. 10⁶ mol. wt and minor species of lower mol. wt. Purified virus particles formed a major and a minor buoyant density component in solutions of caesium salts with densities of 1.26 and 1.25 g cm^-3 in Cs₂SO₄ and 1.30 and 1.29 g cm^-3 in CsCl. The particles contained a single nucleic acid species, presumably single stranded RNA, and a single polypeptide of estimated mol. wt 2.78. 10⁶ and 31 000 respectively. In indirect ELISA, purified particles of WLV and particles in plant sap failed to react specifically with antiserum to nine carlaviruses, 12 potexviruses, three capilloviruses or apple chlorotic leafspot closterovirus, nor was WLV found to react with several of these antisera in immunosorbent electron microscopy or immunoblots. In Marion and Olallie blackberry, WLV in mixture with raspberry bushy dwarf virus (RBDV), but not RBDV alone, induced veinal line-pattern symptoms resembling those of calico disease reported from the USA.     

Critical,pupal and adult weights in the size related metamorphosis of the black lyre leafroller ‘Cnephasia’ jactatana

Adult reproductive performance is linked to the period of feeding done by the final instar larva after attainment of a larval critical weight (L_CW). The highest weight attained by a final instar larva is referred to as the larval maximum weight (L_MW) and is the onset of the pre-pupal period. The relationships between L_CW, pupal weight (P_W) and adult weight (A_W) are described as functions of the L_MW. In the leafroller Cnephasia jactatana (Walker) (Lepidoptera: Tortricidae) L_CW was dependent on larval size and was approximately 75% of the mean L_MW. L_CW was about 29 mg and 36 mg for male and female larvae of 1.18 mm and 1.20 mm head-capsule width, respectively. Over three successive generations of laboratory rearing, P_W was approximately 30% and 25% lower than the L_MW for males and females, respectively. A_W was consistently about 50% and 40% lower than the P_W for males and females, respectively. The decrease in weight from L_MW to P_W was named as the constant D_P and found to be 0.3 for males and 0.25 for females. The total decrease from L_MW to A_W was the constant D_A and was 0.6 for males and 0.5 for females. The duration of the latent feeding period was positively correlated to P_W and A_W. L_CW may be used to derive quality indices that describe and predict pupal and adult performance.

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Résumé Les performances reproductives sont liées à la période d'alimentation du dernier stade larvaire après l'obtention d'un poids critique (L_CW). Le poids maximal atteint au dernier stade larvaire est défini comme le poids larvaire maximal (L_MW), il correspond au début de la période prénymphale. Les relations entre poids de la chrysalide (P_W) et poids de l'audulte A_W) sont présentées comme des fonctions de L_MW). Chez Cnephasia jactatana Walker (Lep. Tortricidae), L_CW dépend de la taille de la chenille et correspond à environ 75% de la valeur moyenne de L_MW. L_CW est respectivement de 29 mg et 36 mg pour les chenilles mâles et femelles dont les capsules céphaliques ont 1,18 et 1,20 mm. Pour 3 générations successives, P_W est environ 30% et 25% inférieur à L_MW des mâles et des femelles. La régression du poids de L_MW à P_W est désignée comme la constante D_P et vaut 0,3 pour les mâles et 0,25 pour les femelles. La régression de L_MW à A_W est désignée comme la régression D_M et vaut 0,6 pour les mâles et 0,5 pour les femelles. La durée de la période d'alimentation latente est liée positivement à P_W et A_W. L_CW peut être utilisé comme indice dérivé décrivant et prédisant les potentialités nymphales et imaginales.

     

The latency of spinach chloroplast phenolase

The latent phenolase in spinach chloroplast membranes could be activated by treatment with various detergents. Examination by thin-layer gel filtration showed the presence of two active proteins (one with lower MW called protein A and the other, protein B). The protein B was converted to A by dilution or on standing, and the latter conversely to the former by concentration. On freezing, an extract of the acetone powder of the chloroplasts, phenolase activity was strikingly reduced, and this is ascribed to an association of the protein A and a low MW (diffusible) substance giving rise to an inactive enzyme-inhibitor complex. The activity declined from autumn to winter, and it appears that the second type of latency due to the formation of the above complex is also involved.