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PubMed1991

Azinphos-methyl residues in apples and spatial distribution of fluorescein in vase-shaped apple trees.

Vase-shaped standard apple trees cv. McIntosh were sprayed with azinphos-methyl at pink, pink and 1st cover and 1st cover only. Residue analyses by gas chromatography revealed detectable residues on foliage until mid summer. At harvest, negligible residue levels were found on the peel and the whole apple. On four trees, fluorescein was sprayed in the same manner as the insecticide and maximum levels of the dye were detected on the outside lower canopy along the row. Minimal concentration of fluorescein was detected on the inner upper canopy away from the direction of the row.

Aerosols↗
PubMed2026

Genome-wide association studies of plant traits and functional analysis of leaf development-related genes in citrus.

Labor-saving and high-light-efficiency tree architecture is a key breeding objective for woody fruit trees like citrus. However, population genetics information on these traits remains limited. In this study, tree architecture, thorn, and leaf traits were evaluated in 353 F2 progeny derived from a cross between Clementine mandarin and precocious trifoliate orange-an early-flowering variety. A random subset of 300 offspring was sequenced for a genome-wide association study (GWAS), which detected 10 216 significantly associated SNPs and defined several major quantitative trait loci (QTLs) for the target traits. Subsequent bulked segregant analysis (BSA) and GWAS on individuals with extreme compound leaf phenotypes mapped the causal gene(s) to a 0.8 Mb region (22.15-22.95 Mb) on chromosome 4. Genetic analysis across multiple hybrid combinations confirmed that the compound leaf trait in trifoliate orange is dominantly inherited and follows Mendelian segregation. Transcriptome profiling of parental leaves at different developmental stages identified a KNOX gene, CiKNAT6, as a candidate. Further validation using CAPS markers and Hi-Tom sequencing demonstrated tight linkage between an InDel polymorphism in CiKNAT6 and leaf shape across diverse citrus species and the F2 population, with co-segregation observed for the compound leaf trait. Due to alternative splicing producing seven splice variants, the CiKNAT6 DNA sequence was selected for genetic transformation experiments. Functional analysis revealed that the Clementine mandarin allele of CiKNAT6 is non-functional owing to an InDel, whereas ectopic expression of the trifoliate orange allele in tobacco and lemon induced leaf curling and reduced leaf size. CRISPR-Cas9 knockout of CiKNAT6 in trifoliate orange resulted in increased leaf area. These findings provide valuable genetic resources and insights for future studies on tree architecture and leaf morphology.

Plant Leaves↗
PubMed2001

Color line search for illuminant estimation in real-world scenes.

The estimation of illuminant color is mandatory for many applications in the field of color image quantification. However, it is an unresolved problem if no additional heuristics or restrictive assumptions apply. Assuming uniformly colored and roundly shaped objects, Lee has presented a theory and a method for computing the scene-illuminant chromaticity from specular highlights [H. C. Lee, J. Opt. Soc. Am. A 3, 1694 (1986)]. However, Lee's method, called image path search, is less robust to noise and is limited in the handling of microtextured surfaces. We introduce a novel approach to estimate the color of a single illuminant for noisy and microtextured images, which frequently occur in real-world scenes. Using dichromatic regions of different colored surfaces, our approach, named color line search, reverses Lee's strategy of image path search. Reliable color lines are determined directly in the domain of the color diagrams by three steps. First, regions of interest are automatically detected around specular highlights, and local color diagrams are computed. Second, color lines are determined according to the dichromatic reflection model by Hough transform of the color diagrams. Third, a consistency check is applied by a corresponding path search in the image domain. Our method is evaluated on 40 natural images of fruit and vegetables. In comparison with those of Lee's method, accuracy and stability are substantially improved. In addition, the color line search approach can easily be extended to scenes of objects with macrotextured surfaces.

Algorithms↗
PubMed1998

Functional dental correlates of food properties in five Malagasy lemur species.

Biomechanical explanations are fundamental to studies of functional dental morphology. Until recently foods were not classified in mechanical categories amenable to a rigorous examination of the fundamental physical relationship between teeth and foods. Fruit, insect and leaf categories, although descriptive, are mechanically heterogeneous. The diets of five Malagasy lemur taxa were described in terms of two mechanical properties, hardness and shear strength, in an earlier study (Yamashita, 1996b). In the present study, correlations between these two physical food properties and second molar tooth features of two lemur families are examined. Several relationships are hypothesized: 1) crest length is expected to be positively correlated with food shear strength; 2) the radius of curvature (r) of cusps is expected to be positively correlated with food hardness; and 3) basin area should increase relative to cusp radius as food hardness increases, and cusp-to-basin ratios should decrease with increasing food hardness. Two additional hypotheses address the debate concerning the relative influences of the most frequently eaten foods versus the most stressful foods in determining tooth form. The results of the predicted relationships are equivocal. 1) Crest length is negatively instead of positively correlated with strong foods. Crest lengths are correlated with quantities of leaf consumption, which are related to leaf shape more than to material composition. 2) As expected, r is positively correlated with food hardness and negatively with shear strength, but this applies to upper molar cusps only. Lower molar cusps complicate simple generalizations of relationships. 3) Hard foods are correlated with a tight fit of occluding cusps and basins instead of the expected loose fit. The most stressful foods eaten (hardest and strongest) have higher correlations with tooth features than the most frequently eaten foods. Several functional complexes can be identified. Hard food items are correlated with short cusps in lemurids, tight occlusal fit, small trigon and large talonid areas, and deep, acute basins. Large, shallow trigons, shallow, unrestricted talonids, and large upper molar basins are indicative of a diet of strong foods. These results demonstrate that some variation in tooth features is explicable with reference to mechanical properties of diet, although the relationships are complex.

Animal Feed↗
PubMed1993

Management of Cooley's anaemia.

The current management of Cooley's anaemia has succeeded in prolonging the patient's life to at least the fourth decade, in allowing a number of the patients to procreate children, and in allowing most of them to lead a nearly unrestricted normal life. The price to be paid for this is the cumbersome and expensive adherence to a rigorous regimen of chronic transfusion and compliance with chelation therapy. Economical and psychological factors make it difficult for many patients to benefit from these advances, but those who can may be reasonably assured of a long and fruitful existence. It must be realized that the only defect in Cooley's anaemia is one of haemoglobin synthesis, and well-managed patients are in any other aspect capable of leading a normal life. In certain areas of the world, such as Cyprus (Loukopoulos et al, 1990) and Sardinia (Cao et al, 1990), extensive and intensive programmes of prenatal screening have reduced to nearly negligible levels the birth of children with Cooley's anaemia (see Chapter 9 this volume). Yet, in many countries a complete management of Cooley's anaemia is today not feasible for economic or cultural reasons, and this disease remains a serious public health problem. The future of the management of Cooley's anaemia appears at the moment full of hopes and frustrations (Gale, 1989; Bank, 1990). However, it is important to understand that if the current group of patients with Cooley's anaemia have to be the beneficiaries of future developments (be it genetic engineering and/or advances in histocompatibility matching), it is necessary that these patients be maintained in excellent clinical shape. It would be very sad when a cure for Cooley's anaemia became available, if most patients could not avail themselves of it because of pre-existing irreversible body damage.

Administration, Oral↗
PubMed1990

Neuronal responses related to reinforcement in the primate basal forebrain.

In the present study neurones recorded in the substantia innominata, the diagonal band of Broca and a periventricular region of the basal forebrain responded differentially to stimuli signalling the availability of fruit juice or saline obtained by making lick responses in two different visual discrimination tasks. The activity of certain neurones reflected the rewarding nature of stimuli used to signal the availability of juice in the tasks, responding to the sight and delivery of both foods and syringes used to deliver juice in tests in which behavioural responses were irrelevant. The activity of other neurones reflected aversion, responding to task stimuli signalling availability of saline and to syringes used to deliver saline to the mouth. In another task an auditory cue that signalled the availability of juice elicited neuronal responses. These neurones also responded to a tone cue used to signal the onset of the trial, and during certain mouth and arm movements which the monkey used to obtain reinforcement. The responses of these differential neurones were similar in most respects in all 3 regions of the basal forebrain. Thus these neurones respond to a range of visual and auditory stimuli that monkeys have learned can be used to obtain reinforcement, but not on the basis of sensory properties such as shape or colour of the stimuli. We conclude that the reinforcement-related nature of the neuronal signal from the basal forebrain could be used to facilitate processing in cortical regions, optimising the functioning of sensory, motor and association cortices, thus increasing the probability of responding appropriately to learned environmental contingencies. We suggest that the properties of these neurones are due to afferent inputs from ventromedial regions of the prefrontal and temporal cortices and amygdala.

Action Potentials↗
PubMed1998

Organization of reaching and grasping movements in the primate cerebellar nuclei as revealed by focal muscimol inactivations.

Two monkeys were trained to point to targets and to retrieve fruit bits from a Kluver board, bottles, and tubes. Once proficient in the tasks, the macaques underwent aseptic surgical implantation of a recording chamber over the cerebellar nuclei on the side of their preferred hand. After recovery from surgery, a series of mapping penetrations were completed to identify task-related areas within the cerebellar nuclei. Muscimol (4- 16 microgram; 1-2 microgram/microliter) was pressure injected at different sites within the forelimb zone, and the resultant deficits were observed as the monkeys performed the behavioral tasks. Quantitative measures of task performance were supplemented by direct observation of live and videotaped performance. The locations of nuclear inactivation sites were reconstructed from marking lesions and tracks visible in histological sections. Injections placed in the cerebellar interpositus nucleus and adjacent regions of dentate caused a variety of deficits in forelimb function. A prominent anteroposterior specialization was apparent within the forelimb zone of this intermediate nuclear region. Injections into the anterior interpositus nucleus and adjacent dentate impaired preshaping of the hand and the manipulation of objects, whereas injections placed more posteriorly in posterior interpositus nucleus and adjacent dentate produced deficits in the aiming of reach and the stability of the arm. During anterior injections, the monkeys failed to adequately extend their fingers in preparation for target contact, as documented for >85% of the reaches in the pointing task of monkey J. Up to 38% of the fruit bits it attempted to retrieve from the Kluver board were dropped. In comparison, during posterior inactivations, 15% were dropped and during control conditions 3% were dropped. The monkeys made significantly greater pointing errors during posterior inactivations (11 times for monkey J and 4 times for monkey C) than during anterior inactivations (8 times for monkey J and 2 times for monkey C). We refer to the region producing hand deficits as the anterior hand zone and the region producing reaching deficits as the posterior reach zone. These results are discussed in relation to the problem of achieving spatiotemporal coordination in the large population of nuclear cells that participate in any given movement. The results do not favor the hypothesis that coordination is achieved through a selection of Purkinje cells along beams of parallel fibers. Instead, it is proposed that distal and proximal musculature is coordinated by the adaptive influences of climbing fiber input to Purkinje cells. We envision a relatively nonspecific recruitment of anterior and posterior nuclear cells due to positive feedback in the limb premotor network, which then is shaped into an appropriate spatiotemporal pattern of discharge through the inhibitory input from Purkinje cells.

Animals↗
PubMedDate not supplied

[A food cognition questionnaire].

BACKGROUND: Many authors evoke the role of cognition in the persistence of symptoms or in relapse. In pathology the cognitions produced by the patients are called dysfunctional or erroneous. The content of the cognitions are words or images issued from the treatment of information. In emotional disorders, the structure of thoughts named dysfunctional "schemata" involves a biased treatment of information and leads to erroneous cognitions. Several studies have attempted to elicit the most specific cognitions of different diseases. In this field, Hollon and Kendall found 36 cognitions specific to depression gathered in the automatic thoughts questionnaire (ATQ). In the same spirit, Beck et al. gathered 14 cognitions of anxiety and 12 depressed cognitions in the cognition check list (CCL). In the etiology and maintenance of eating disorders the cognitions take a large place. Around 1980 cognitive dysfunctioning was described and concerned food, interpersonal relationship and body shape. A few years later, some experimental studies explored these processes. The Stroop test, a categorization task, showed specific cognitive impairment in with patients eating disorders versus normal control subjects. It was then established that cognitive errors were based on food cognitions in restrictive patients, whereas they were based on body shape cognitions in bulimic patients. In several famous papers, Garner described typical cognitions of eating disorder patients and distinguished food-cognitions, eating-cognitions using case reports. As far as we know there is no clinical tool concerning such cognitions in France. That is the main motivation of the authors. AIM OF THE STUDY: The aim of this paper was to determine the characteristic cognitions of anorexic, anorexic-bulimic and bulimic patients and to compare them with those of normal control subjects. The goal of the study was to create a food cognition questionnaire. FIRST STEP METHODS: In the first step, food cognitions were collected among female eating disorder patients and normal female control subjects during systematic investigation. Ninety-two women were assessed and provided more than 3 000 food cognitions. Two independent psychologists identified the most frequent cognition per group and thus retained 115 food items. These items were randomly assigned. This provided the questionnaire. To illustrate the latter, here are the first five items: 1) Apricots are good for the health because they are rich in vitamins. 2) Pears are big fruit, difficult to digest. 3) Canned fruit is soaked with sugar. 4) Banana is a fruit which makes one put on weight. 5) White coloured food give the impression that it is not alive... The list of possible answers was: never, rarely, sometimes, often enough, often, always. SECOND STEP METHODS: In the second step, the food cognition questionnaire was proposed to 217 women including 131 eating disorder patients (53 anorexic, 50 anorexic bulimic, 28 bulimic) and 86 normal control subjects. The values of body mass index and the eating attitude test differed when we compared the two groups, and the mean age was close to 26 years in both groups. RESULTS: The statistic analysis highlighted six discriminative variables: two clinical criteria (weight and height) and four food-items given below: Q24: When I see food being fried, I feel the grease all over my body. Q76: When I start a cookie packet, I eat it up. Q102: When I feel anxious, I crave for food to fill my body. Q106: Eating pastry gives me heart-burn and makes me belch. The statistical model allowed us to differentiate eating disorder patients from normal control subjects. The content of the four food items is in agreement with experimental and clinical data. All these items included some aspects of the quality or quantity of food and also the negative consequences of food consumption on the body. CONCLUSION: To conclude, the model can help clinicians identify the patients and then initiate treatment. We also insist on the fact that this study is new and empirical, and should be extended by determining some food items for example, which would clarify the difference of behaviour between anorexics and bulimics.

Adult↗
PubMed2006

Health benefits of nuts: potential role of antioxidants.

A diet rich in fruits, vegetables and minimally refined cereals is associated with lower risk for chronic degenerative diseases. Since oxidative stress is common in chronic degenerative disease, it has been assumed that dietary antioxidants may explain this protective effect. Every dietary plant contains numerous types of antioxidants with different properties. Many of these antioxidants cooperate in oxidative stress reduction in plants, and we hypothesize that many different antioxidants may also be needed for the proper protection of animal cells. To test this hypothesis, it is useful to identify dietary plants with high total antioxidant content. Several nuts are among the dietary plants with the highest content of total antioxidants. Of the tree nuts, walnuts, pecans and chestnuts have the highest contents of antioxidants. Walnuts contain more than 20 mmol antioxidants per 100 g, mostly in the walnut pellicles. Peanuts (a legume) also contribute significantly to dietary intake of antioxidants. These data are in accordance with our present extended analysis of an earlier report on nut intake and death attributed to various diseases in the Iowa Women's Health Study. We observed that the hazard ratio for total death rates showed a U-shaped association with nut/peanut butter consumption. Hazard ratio was 0.89 (CI = 0.81-0.97) and 0.81 (CI = 0.75-0.88) for nut/peanut butter intake once per week and 1-4 times per week, respectively. Death attributed to cardiovascular and coronary heart diseases showed strong and consistent reductions with increasing nut/peanut butter consumption. Further studies are needed to clarify whether antioxidants contribute to this apparent beneficial health effect of nuts.

Aged↗
PubMedDate not supplied

Chemical identification of the sources of commercial Fructus Chebulae.

Twenty-eight commercial samples of Fructus Chebulae were collected from local herbal markets in Taiwan and were determined to have been derived from Terminalia chebula Retz. and Terminalia chebula Retz. var. parviflora Thwaites, which differ markedly in external appearance. Ten tannin-related constituents [gallic acid (1), chebulic acid (2), punicalagin (4), chebulanin (7), corilagin (8), neochebulinic acid (9), ellagic acid (11), chebulagic acid (12), chebulinic acid (13) and 1,2,3,4,6-penta-O-galloyl-beta-D-glucose (14)] were identified and quantified by HPLC. Samples derived from T. chebula. var. parviflora, which are typically round-shaped, generally contained higher concentrations of 13 and 14 but lower levels of 12 compared with those from T. chebula, which are largely oval-shaped. The ratio of the concentration of 14 to that of 4 may serve as a potential parameter for differentiating samples from the two origins (T. chebula, ratio 0.6 +/- 0.3; T. chebula. var. parviflora, ratio 3.4 +/- 2.2). Levels of the three major bioactive constituents 12-14 were found to provide good references for the quality assessment of Fructus Chebulae. The ratio of the concentration of 12 to that of 14 may offer a guideline for determining quality as well as origin of the drug (lower-grade T. chebula, ratio 12.4 +/- 6.0; medium-grade T. chebula, ratio 8.8 +/- 7.9; higher-grade T. chebula, ratio 3.2 +/- 0.8; T. chebula var. parviflora, ratio 1.6 +/- 0.7).

Carboxylic Acids↗
PubMed1991

Development in Myxococcus xanthus involves differentiation into two cell types, peripheral rods and spores.

Myxococcus xanthus, a gram-negative bacterium, has a complex life cycle. In response to starvation, most cells in a population participate in the formation of multicellular aggregates (i.e., fruiting bodies) in which cells differentiate into spores. However, some cells do not enter aggregates. In this and the two accompanying reports, the biology and physiology of these nonaggregated cells is examined. A technique to separate aggregated cells from nonaggregated cells was developed; then differentiating cells at stages throughout the course of development were isolated. In this report we (i) describe peripheral rods, those cells which remain outside aggregates after aggregation has ceased in the rest of the population; (ii) document the occurrence of peripheral rods in several wild-type strains; and (iii) characterize the expression of developmentally regulated genes in both aggregated and nonaggregated cells. These studies have shown that myxobacterial hemagglutinin, protein S (Tps), protein S1 (Ops), protein C, and several phosphatase activities are expressed in cell-type-specific patterns. These data demonstrate that peripheral rods constitute a cell type distinct from either vegetatively growing cells or spores. The description of a second, late developmental cell type (in addition to spores) opens an entirely new line of investigation in M. xanthus, i.e., the regulation of the differentiation of vegetatively growing cells into two cell types that differ significantly in biology, shape, and localization within the population.

Bacterial Outer Membrane Proteins↗
PubMed1988

Steroid hormones and the brain: linking "nature" and "nurture".

Contrary to earlier belief, the genetic constitution of each cell of the body ("nature") is subject to modulation by environmental factors ("nurture") which act throughout the life of the organism to shape the individual characteristics. The nervous system adapts and changes with the environment that the organism experiences through genomic activity controlled by chemical messengers from other nerve cells and from endocrine secretions. The nervous system expresses receptors for a number of circulating hormones, and the location of these hormone receptors has revealed a great deal about the neuroanatomy of neuroendocrine and behavioral control processes. The brain controls the endocrine system through the hypothalamus and pituitary gland, and it responds to circulating hormones throughout each stage of life. These effects begin during early development (eg., sexual differentiation of the brain; effects of maternal or neonatal stress). They continue in adult life in response to cyclic events (eg., season of year; time of day, controlling reproduction and daily activity-sleep rhythms of behavior); and they also include the behavior of other animals which alters hormone output. Hormones also operate during the aging process and under conditions which induce neural damage such as hypoxia and stress. This overview summarizes involvement of steroid hormones of gonads and adrenals in many of these processes and also examines the features of the genomic activity which is modified by these hormones. This area of research is fruitful because it brings together molecular, anatomical, physiological and behavioral approaches in an attempt to understand the long-term plasticity of the nervous system.

Animals↗
PubMed1997

Immunocytochemical electron microscopic study and western blot analysis of myosin, paramyosin and miniparamyosin in the striated muscle of the fruit fly Drosophila melanogaster and in obliquely striated and smooth muscles of the earthworm Eisenia foetida.

Miniparamyosin is a paramyosin isoform (55-60 kDa) that has been isolated in insects (Drosophila) and immunolocalized in several species of arthropods, molluscs, annelids and nematodes. In this study, the presence and distribution of this protein, in comparison with that of paramyosin and myosin, has been examined in the striated muscle (tergal depressor of trochanter) of Drosophila melanogaster, and the obliquely striated muscle (body wall) and the smooth muscle (outer layer of the pseudoheart) of the earthworm Eisenia foetida by means of immunocytochemical electron microscopic study and Western blot analysis miniparamyosin paramyosin and myosin antibodies from Drosophila. In the striated muscle of D. melanogaster, the three proteins were immunolocalized along the length of the thick filaments (A-bands). The distribution of immunogold particles along these filaments was uniform. The relative proportions miniparamyosin/paramyosin/myosin (calculated by counting the number of immunogold particles) were: 1/10/68. In the obliquely striated muscle of E. foetida, immunoreactions to the three proteins were also found in the thick filaments, and the relative proportions miniparamyosin/paramyosin/myosin were 1/2.4/6.9. However, whereas the distribution of both myosin and miniparamyosin along the thick filament length was uniform, paramyosin immunolabelling was more abundant in the extremes of thick filaments (the outer zones of A-bands in the obliquely striated muscle), where the thick filaments become thinner than in the centre (the central zone of A-bands), where these filaments are thicker. The relative proportions of paramyosin in the outer and of paramyosin in the central zones of A-bands were 4/1. This irregular distribution of paramyosin along the thick filament length might be actual but it may also be explained by the fusiform shape of thick filaments in the earthworm: assuming that paramyosin is covered by myosin, paramyosin antigens would be more exposed in the tips than in the centre of thick filaments. If miniparamyosin is, in turn, covered by paramyosin, the exposure of miniparamyosin antigens would be low even in the tips of thick filaments, and this might explain the scanty immunoreaction observed for this protein and the absence of a higher number of immunogold particles in the extremes of thick filaments. The distribution of the three proteins in the earthworm smooth muscle was as in the obliquely striated muscle, although the proportions miniparamyosin/paramyosin/myosin were 1/1.5/5.2; this is, immunoreactions to paramyosin and miniparamyosin were lower than in the obliquely striated muscle.

Animals↗
PubMed1993

Ultrastructural characteristics of atrial, ventricular and subendocardial (Purkinje) cells of the fruit-eating bat Eidolon helvum.

The ultrastructure of the myocardium of the large (285 gm) fruit-eating bat (Eidolon helvum) provides further evidence that, among mammalian species, different types of cardiac myocytes are morphologically heterogeneous. Atrial cells of this species, like those of smaller bats previously studied, have few of the natriuretic hormone-containing granules. These granules are also small, with a mean diameter of 176 +/- 3.9 nm, in comparison with those of the rat (230 +/- 5.8 nm) and mouse (211 +/- 4.7 nm). In all types of myocytes of the bat investigated, mitochondrial matrix granules are more prominent than in those of the rat and mouse. Also distinctive are the Purkinje cells which, aside from their large size (30 microns) and lack of T-tubules, have atrial granule-like inclusions. These cells are well endowed with mitochondria (28% of cytoplasmic volume) and with lipid bodies but have few glycogen granules. Their myofibrillae (33%) are well aligned. The ventricular cells (average diameter 14 microns) have nearly equal volumes of mitochondria (41%) and myofibrils (47%). Mitochondrial cristae, however, are not compactly organized. Lipid material is found in the matrix of the mitochondria. Extensive evaginations of endothelial cells of the bat endocardium appear continuous with endothelial vacuoles. In these endothelial cells, there are also many dense granules of varying shapes and sizes.

Animals↗
PubMed2003

crinkle, a novel symbiotic mutant that affects the infection thread growth and alters the root hair, trichome, and seed development in Lotus japonicus.

To elucidate the mechanisms involved in Rhizobium-legume symbiosis, we examined a novel symbiotic mutant, crinkle (Ljsym79), from the model legume Lotus japonicus. On nitrogen-starved medium, crinkle mutants inoculated with the symbiont bacterium Mesorhizobium loti MAFF 303099 showed severe nitrogen deficiency symptoms. This mutant was characterized by the production of many bumps and small, white, uninfected nodule-like structures. Few nodules were pale-pink and irregularly shaped with nitrogen-fixing bacteroids and expressing leghemoglobin mRNA. Morphological analysis of infected roots showed that nodulation in crinkle mutants is blocked at the stage of the infection process. Confocal microscopy and histological examination of crinkle nodules revealed that infection threads were arrested upon penetrating the epidermal cells. Starch accumulation in uninfected cells and undeveloped vascular bundles were also noted in crinkle nodules. Results suggest that the Crinkle gene controls the infection process that is crucial during the early stage of nodule organogenesis. Aside from the symbiotic phenotypes, crinkle mutants also developed morphological alterations, such as crinkly or wavy trichomes, short seedpods with aborted embryos, and swollen root hairs. crinkle is therefore required for symbiotic nodule development and for other aspects of plant development.

Cell Surface Extensions↗
PubMed1987

Further characterization of an unusual plant Mollicutes species of uncertain taxonomic status.

PPAV is a type of Mollicutes that was isolated in SP4 medium from seeds of apples affected by proliferation, a disease in which mycoplasma-like organisms (MLOs) are involved. However, PPAV is probably not the etiological MLO agent for at least two reasons: 1) optimal temperature growth is 43 C, and 2) in spite of numerous isolation attempts over several years, no second PPAV culture could be obtained. PPAV is surrounded by a single cytoplasmic membrane and forms typical fried egg-shaped colonies on solid medium. The organism grows in simplified mycoplasma media, such as BSR. In growth inhibition, it shows no serological relationships with any other mycoplasmas or acholeplasmas, including those cultured from the surfaces of plants. The absence of relatedness of PPAV to other Mollicutes was confirmed by DNA hybridization studies. The genome of PPAV is close to 10(9) daltons and contains 25.2 mol % G + C. Its genome size is similar to that of Acholeplasma spp. and Spiroplasma spp. It has, however, a clearcut sterol requirement and therefore cannot be an acholeplasma. Neither is it a spiroplasma since, though filamentous in BSR medium, it has never shown signs of helicity. Hence, PPAV is a taxonomical paradox.

Acholeplasma↗
PubMed1986

Selection of Dictyostelium mutants defective in cytoskeletal proteins: use of an antibody that binds to the ends of alpha-actinin rods.

A monoclonal antibody, mAb 47-19-2, was used to study the subunit topology of the rod-shaped alpha-actinin molecules of Dictyostelium discoideum and to screen for mutants defective in the production of alpha-actinin. Electron microscopy of rotary-shadowed alpha-actinin-antibody complexes showed binding of mAb 47-19-2 to both ends of the alpha-actinin rods and cleavage of the rods into its subunits, indicating that the two subunits of alpha-actinin extend in an anti-parallel mode through the whole length of the rod. The antibody binding sites were located in close proximity to the sites responsible for actin cross-linking, which is consistent with the blocking activity of the antibody. In a mutant, HG1130, no antibody label was detected in colony blots, and by immunoblotting of mutant proteins separated by SDS-PAGE, only trace amounts of alpha-actinin were found. The mutant showed normal binding of antibodies directed against the actin-binding proteins severin and capping protein. The mutation responsible for the alpha-actinin defect was recessive and located on linkage group I of the genetic map of D. discoideum. HG1130 cells grew on bacteria at a normal rate and also axenically like cells of the parent strain AX2. After starvation the mutant cells expressed the contact site A glycoprotein, a marker of the aggregation-competent stage, and reacted chemotactically to cyclic AMP. The aggregation patterns and fruiting bodies of the mutant appeared to be normal. Patching and capping on the surface of HG1130 cells was induced by antibodies against the contact site A glycoprotein.(ABSTRACT TRUNCATED AT 250 WORDS)

Actinin↗
PubMedDate not supplied

Physicochemical properties and structural changes in vegetative tissues as affected by a direct current electrical field.

Cylindrical pieces of potato, sweet potato, kohlrabi, radish, and pear were interposed between a pair of electrodes, and a direct current was applied. A special custom-made apparatus enabled the use of differently shaped electrodes. The electrical field was applied for 1 min at 40 V/cm and caused a reduction in specimen weight by a minimal value of 2.7% of initial weight in sweet potato to a maximum 38.4% in pear. The affected area of the tissue resembled the shape of the electrode. Pores were produced in the tissue (from the anode side), possibly promoting slow release of minerals and other cell components from the contracted specimens. From the cathode side, cell "sealing" could be observed. Weight loss was dependent on the mechanical properties of the nontreated vegetative tissue specimens. After confirmation that all samples pass through induced electrical shrinkage, further work, executed only on potato, demonstrated that after electrical treatment the samples were less brown (higher L values). In addition, a dependence of weight loss on current intensity, electrode diameter, and surface ratio between the electrode and specimen was shown. The reduction in weight loss could be useful for initial drying of vegetative materials. Indirect proof of a decrease in enzyme activity as a result of electrical field application could be beneficial in replacing traditional methods for browning prevention.

Catechol Oxidase↗