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PubMed1990

Sequence variability and developmental expression of S-alleles in self-incompatible and pseudo-self-compatible petunia.

We investigated the structure and expression of three S-alleles of Petunia hybrida in self-incompatible varieties and in a pseudo-self-compatible line in which the self-incompatibility response is defective. Comparison of derived amino acid sequences from different gametophytic S-alleles revealed a pattern of sequence conservation and variability that was highly nonrandom. In self-incompatible varieties, petunia S-locus mRNA accumulates preferentially in styles during the transition from bud self-compatibility to self-incompatibility. S-Allele sequences homologous to the cloned S1 allele were present in a pseudo-self-compatible variety, and were expressed at levels indistinguishable from those observed in a self-incompatible line homozygous for the S1 allele. Taken together, our data indicate that (1) limited sequence differences may confer allelic specificity, (2) S-locus mRNAs accumulate in a precise organ-specific pattern during floral development, and (3) the ability to inhibit the growth of incompatible pollen tubes appears to require a threshold accumulation of the stylar gene product, along with the participation of as yet undefined pollen gene products.

Alleles↗
PubMed1997

Prenatal origins of asthma and allergy.

The prevalence of asthma and related allergic disorders has increased considerably over the last 25 years. Genetic stock has not changed, so environmental factors must have influenced the phenotype. Infants who develop allergy already have an altered immune response at birth. We have investigated the development of immune responses during gestation and the effect of maternal allergen exposure during pregnancy and infant exposure in the first month of life on the development of allergy and disease. There was higher specific peripheral blood mononuclear cell proliferation to house dust mite (P = 0.01) and birch pollen (P = 0.004) in the third trimester compared with the second trimester, with the first positive responses seen at 22 weeks gestation. Maternal exposure to birch pollen after 22 weeks resulted in higher (P = 0.005) infant peripheral blood mononuclear cell responses to birch pollen at birth. Infants born at term, with at least one atopic, asthmatic parent, who developed allergic symptoms and positive skin prick test by one year of age had raised proliferative responses to house dust mites at birth compared to those with no symptoms (P = 0.01). In genetically predisposed individuals, antenatal factors, including maternal and thereby fetal exposure to allergens and maternoplacental-fetal immunological interactions, are active in determining whether an allergic predisposition is manifested as disease.

Allergens↗
PubMed1993

In vitro synthesis of IL-4 by human CD4+ T cells requires repeated antigenic stimulation.

Although Th2 helper cell clones produce IL-4 and IL-5, CD4+ T cells taken fresh from lymphoid organs of mice produce IL-2 and some IFN-gamma, but not IL-4 or IL-5. The exact parameters that enhance the synthesis of IL-4, IL-5, and particularly IL-10 from resting antigen-specific CD4+ T cells is not yet clear. We therefore examined the kinetics of, and the parameters that affect, the development of IL-4, IL-5, and IL-10 production in bulk populations of antigen-specific human CD4+ T cells. We demonstrated that in vitro stimulation of human peripheral blood lymphocytes with antigen (tetanus toxoid or a viral antigen, Varicella zoster) for several days resulted in the production of IL-2 and IFN-gamma, but little or no IL-4 or IL-5. This cytokine profile was observed even when CD4+ T cells from allergic donors were stimulated once in vitro with allergen (rye grass pollen, Lolium perenne I, or dust mite allergen, Dermatophagoides farinae). The observed cytokine profile reflected that of the vast majority of antigen-specific T cells, since we studied the response of bulk populations of CD4+ T cells rather than that of a "selected" number of antigen-specific T cell clones. Furthermore, we observed that human CD4+ T cells from either allergic or nonallergic individuals failed to produce significant quantities of IL-4, IL-5, or IL-10 even after several rounds of stimulation with soluble protein (nonallergen) antigens such as tetanus toxoid or Var. z. However, large quantities of these cytokines were produced when stimulation of the T cells occurred in the presence of rIL-4, but only after two stimulations in vitro with antigen over a period of greater than 7 days. In addition, substantial quantities of IL-4, IL-5, and IL-10 were produced by CD4+ T cells from allergic subjects in the absence of exogenous IL-4, but only after two stimulations in vitro with allergens such as rye grass pollen or dust mite allergen. These results indicate that the development of IL-4 and IL-5 synthesis occurs in peripheral blood CD4+ T cells in a stepwise fashion, first with the production of IL-2 and IFN-gamma, and later with the production of IL-4 and IL-5.(ABSTRACT TRUNCATED AT 250 WORDS)

Antigens↗
PubMed1996

A Similar Dichotomy of Sugar Modulation and Developmental Expression Affects Both Paths of Sucrose Metabolism: Evidence from a Maize Invertase Gene Family.

Invertase and sucrose synthase catalyze the two known paths for the first step in carbon use by sucrose-importing plant cells. The hypothesis that sugar-modulated expression of these genes could provide a means of import adjustment was initially suggested based on data from sucrose synthases alone; however, this hypothesis remained largely conjectural without critical evidence for invertases. Toward this end, a family of maize invertases was cloned and characterized. Here, we show that invertases are indeed sugar modulated and, surprisingly, like the sucrose synthase genes, fall into two classes with contrasting sugar responses. In both families, one class of genes is upregulated by increasing carbohydrate supply (Sucrose synthase1 [Sus1] and Invertase2 [Ivr2]), whereas a second class in the same family is repressed by sugars and upregulated by depletion of this resource (Shrunken1 [Sh1] and Invertase1 [Ivr1]). The two classes also display differential expression during development, with sugar-enhanced genes (Sus1 and Ivr2) expressed in many importing organs and sugar-repressed, starvation-tolerant genes (Sh1 and Ivr1) upregulated primarily during reproductive development. Both the Ivr1 and Ivr2 invertase mRNAs are abundant in root tips, very young kernels, silk, anthers, and pollen, where a close relationship is evident between changes in message abundance and soluble invertase activity. During development, patterns of expression shift as assimilate partitioning changes from elongating silks to newly fertilized kernels. Together, the data support a model for integrating expression of genes differentially responsive to carbohydrate availability (i.e., feast and famine conditions) with developmental signals. The demonstration that similar regulatory patterns occur in both paths of sucrose metabolism indicates a potential to influence profoundly the adjustment of carbon resource allocation.

Journal Article↗
PubMed1996

Preparation of tomato meiotic pachytene and mitotic metaphase chromosomes suitable for fluorescence in situ hybridization (FISH).

Fluorescence in situ hybridization (FISH) is an increasingly powerful tool with a variety of applications in both basic and applied research. With excellent genetic, cytogenetic and molecular maps available, the tomato genome provides a good model to benefit from the full potential of FISH. Tomato chromosomes at mitotic metaphase are small and not particularly suitable for high-resolution FISH. In contrast, chromosomes at meiotic pachytene are about 15 times longer, and easier to identify by their differences in chromosome arm lengths and chromomere pattern. We have developed a technique for preparing chromosomal spreads of young pollen mother cells at mid-prophase I which is suitable for FISH. In a first series of experiments, the hybridization patterns of three classes of repetitive DNA sequences were studied in single and multicolour FISH.

Chromosomes↗
PubMed2002

Intergeneric hybridization between Erucastrum canariense and Brassica rapa. Genetic relatedness between E(C) and A genomes.

An intergeneric hybrid between a wild species, Erucastrum canariense (2n = 18; E(C)E(C)), and a cultivated oilseed brassica species, Brassica rapa (2n = 20; AA), was synthesized through ovary culture in White's basal medium supplemented with casein hydrolysate. Morphological, cytological and DNA-based analysis helped to establish the hybrid nature of the derived plants. Hybrid plants were morphologically intermediate between the two parents and were completely male, as well as female sterile. Cytological analysis revealed the occurrence of 19 I in about 38% of the PMCs investigated. However 1-8 bivalents/PMC were also observed, indicating a significant level of homology between the two genomes. Normal chromosome pairing and pollen fertility was restored following colchiploidy. The intergeneric amphiploid developed during the investigation can be used as a bridging species for the transfer of desirable genes from E(C) to cultivated genomes (especially A and C), and for resistance to Alternaria blight and mustard aphid. Under field conditions, the E. canariense intergeneric hybrid and the amphiploid appeared to be moderately resistant to Alternaria blight and also harboured a significantly lower population of mustard aphid than the cultivated B. rapa.

Journal Article↗
PubMed1987

Bronchial asthma. Mechanisms and management of a complex obstructive airway disease.

Airway hyperreactivity to physical, chemical, and pharmacologic stimuli is a hallmark of bronchial asthma. In patients with extrinsic (allergic) asthma, in whom an immunologic mechanism of the IgE type can be demonstrated, specific sensitivity develops to a variety of common environmental substances, including pollen, fungus spores, house dust mites, and animal danders. Persons with intrinsic asthma, in whom immunologic mechanisms are hard to demonstrate, often have chronic sinus disease and nasal polyps and manifest clinical intolerance to nonsteroidal antiinflammatory agents. Evaluation of asthma includes a history and complete physical examination, skin tests, radioallergosorbent tests, pulmonary function tests, blood gas determination, and inhalation challenge tests. Treatment is focused on environmental control, pharmacotherapy, and immunotherapy.

Adrenal Cortex Hormones↗
PubMed2000

Development of a set of near isogenic and backcross recombinant inbred lines containing most of the Lycopersicon hirsutum genome in a L. esculentum genetic background: a tool for gene mapping and gene discovery.

A novel population consisted of a set of 99 near isogenic lines (NILs) and backcross recombinant inbred lines (BCRILs) derived from a cross between the cultivated tomato Lycopersicon esculentum cv. E6206 and L. hirsutum accession LA1777 is presented. Most of the lines contain a single defined introgression from L. hirsutum in the L. esculentum genetic background and together, the lines provide a coverage of more than the 85% of the L. hirsutum genome. These lines represent a new tool to uncover the genetic resources hidden in L. hirsutum as well as to study the genes responsible of its unique biology. Furthermore, the study of the allelic frequency and heterozygosity among BCRILs showed that specific genomic regions were likely subjected to unintentional selection pressures during the stock development. Genes involved in the reproductive behavior and (or) pollen viability are hypothesized to be responsible for these alterations.

Breeding↗
PubMed1986

[Cutaneo-systemic necrotizing vasculitis occurring during desensitization].

The authors report a case of cutaneo-systemic necrotizing vasculitis, predominantly affecting the skin and digestive tract, observed in an asthmatic patient undergoing desensitization with Graminaceae pollen extract and mite-enriched house dust. Vasculitis developed 22 months after the first injections, became autonomous after the end of treatment and responded well to systemic corticosteroid therapy in daily doses of 1 mg/kg. The patient was followed up for 8 months during which the vasculitis did not recur, despite reduction in steroid dosage. Reports of necrotizing vasculitis occurring during desensitization seem to be very rare. They raise the problem of whether specific immunotherapy plays a role in the pathogenesis of vasculitis. Most of the characteristics that emerged from the cases previously published are concordant with those found in our patient: the interval between the first injections and the initial symptoms varied from 45 days to 8 years; in every case the condition followed its own course after the injections were discontinued; most patients were being desensitized to several allergens; the cutaneous symptoms were pronounced, eosinophilia was moderate and hepatitis B serology was constantly negative. The few prospective studies aimed at determining, by different methods, the levels of circulating immune complexes (CIC) have given conflicting results. Atopic subjects have high CIC levels, but these do not seem to be influenced by desensitization. The nature of the CIC remains unknown, and the various suggestions put forward (cross-reaction between blocking IgG and auto-antibodies, CIC [blocking IgG, anti-idiotype antibodies]) require confirmation, although the hypothesis of pathogenic CIC (allergen, blocking IgG) is unlikely to be correct.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Cortex Hormones↗
PubMed2005

Correlation between conjunctival provocation test results and conjunctival symptoms in pollinosis - preliminary report.

The aim of the study was to investigate the correlation between the level of reactivity in conjunctival provocation test and conjunctival symptoms that develop during the pollination season in grass allergic patients. Conjunctival provocation test with grass pollen allergens was performed in 22 patients suffering from pollinosis. During grass pollination season all patients monitored their symptoms with Symptoms Score Cards. A parallel measurement of the level of grass pollen count was carried out on a daily basis by volumetric method. The mean grass pollen count which triggered the reaction in individual patients depended on the results of conjunctival provocation test. The lowest pollen count level was observed in cases of patients with positive conjunctival provocation test at low allergen extract concentration of 160 and 500 BU/ml, whereas the highest count in cases of 1,600 BU/ml. The difference between the results was found to be statistically significant. A threshold grass pollen concentration for conjunctival symptoms was established at the level of 22 grains/m (3). We conclude that the patients with pollinosis and high reactivity in conjunctival provocation test develop conjunctival symptoms earlier during grass pollination season than the patients who are characterised by lower reactivity during conjunctival provocation test.

Adult↗
PubMed1988

The spectrum of allergenic pollens in Italy. A computerized method of aerobiological monitoring.

The monitoring of airborne pollens that provoke allergy is of interest to clinicians to enable them to correlate chronologically the relationship between pollen concentrations in the atmosphere and the symptoms of patients with pollen-related allergies. In Italy there are now 60 centres for monitoring airborne allergenic pollens, the data from which are compiled and filed using software developed by the Italian Association of Aerobiology (AIA) and run on personal computers. These data are then fed into a central data bank to which all centres have access. This information system makes it possible to achieve the following objectives: 1) to standardise monitoring methods, 2) to recognise varieties of pollen that cause allergies, 3) to improve the exchange and comparison of information among operators by compiling the results in graphs, and 4) to notify clinicians about atmospheric concentrations of allergenic pollens so that improved therapy can be provided.

Air Pollution↗
PubMed1990

Polyamines and Flower Development in the Male Sterile Stamenless-2 Mutant of Tomato (Lycopersicon esculentum Mill.) : II. Effects of Polyamines and Their Biosynthetic Inhibitors on the Development of Normal and Mutant Floral Buds Cultured in Vitro.

The floral organs of the male sterile stamenless-2 (sl-2/sl-2) mutant of tomato (Lycopersicon esculentum Mill.) contain significantly higher level of polyamines than those of the normal (R Rastogi, VK Sawhney [1990] Plant Physiol 93: 439-445). The effects of putrescine, spermidine and spermine, and three different inhibitors of polyamine biosynthesis on the in vitro development of floral buds of the normal and sl-2/sl-2 mutant were studied. The polyamines were inhibitory to the in vitro growth and development of both the normal and mutant floral buds and they induced abnormal stamen development in normal flowers. The inhibitors of polyamine biosynthesis also inhibited the growth and development of floral organs of the two genotypes, but the normal flowers showed greater sensitivity than the mutant. The inhibitors also promoted the formation of normal-looking pollen in stamens of some mutant flowers. The effect of the inhibitors on polyamine levels was not determined. The polyamine-induced abnormal stamen development in the normal, and the inhibitor-induced production of normal-looking pollen in mutant flowers support the suggestion that the elevated polyamine levels contribute to abnormal stamen development in the sl-2/sl-2 mutant of tomato.

Journal Article↗
PubMed2005

The making of gametes in higher plants.

Higher plants have evolved to be one of the predominant life forms on this planet. A great deal of this evolutionary success relies in a very short gametophytic phase which underlies the sexual reproduction cycle. Sexual plant reproduction takes place in special organs of the flower. In most species the processes of gametogenesis, pollination, syngamy and embryogenesis are sequentially coordinated to give rise to a functional seed in a matter of few weeks. Any of these processes is so intricately complex and precisely regulated that it becomes no wonder that each involves more specific genes and cellular processes than any other function in the plant life cycle. While variability generation - the evolutionary output of the sexual cycle - is the same as in any other Kingdom, plants do it using a completely original set of mechanisms, many of which are not yet comprehended. In this paper, we cover the fundamental features of male and female gametogenesis. While the physiological and cellular bases of these processes have been continuously described since the early nineteen century, recent usage of Arabidopsis and other species as central models has brought about a great deal of specific information regarding their genetic regulation. Transcriptomics has recently enlarged the repertoire and pollen became the first gametophyte to have a fully described transcriptome in plants. We thus place special emphasis on the way this newly accumulated genetic and transcriptional information impacts our current understanding of the mechanisms of gametogenesis.

Flowers↗
PubMed2006

8. The development and evolution of division of labor and foraging specialization in a social insect (Apis mellifera L.).

How does complex social behavior evolve? What are the developmental building blocks of division of labor and specialization, the hallmarks of insect societies? Studies have revealed the developmental origins in the evolution of division of labor and specialization in foraging worker honeybees, the hallmarks of complex insect societies. Selective breeding for a single social trait, the amount of surplus pollen stored in the nest (pollen hoarding) revealed a phenotypic architecture of correlated traits at multiple levels of biological organization in facultatively sterile female worker honeybees. Verification of this phenotypic architecture in "wild-type" bees provided strong support for a "pollen foraging syndrome" that involves increased senso-motor responses, motor activity, associative learning, reproductive status, and rates of behavioral development, as well as foraging behavior. This set of traits guided further research into reproductive regulatory systems that were co-opted by natural selection during the evolution of social behavior. Division of labor, characterized by changes in the tasks performed by bees, as they age, is controlled by hormones linked to ovary development. Foraging specialization on nectar and pollen results also from different reproductive states of bees where nectar foragers engage in pre-reproductive behavior, foraging for nectar for self-maintenance, while pollen foragers perform foraging tasks associated with reproduction and maternal care, collecting protein.

Animals↗
PubMed2004

Convergent evolution within the genus Solanum: the specialised anther cone develops through alternative pathways.

Many angiosperm species produce cones of anthers which release pollen through pores in response to vibration by pollinating bees ("buzz-pollination"). Anther cones of varying degrees of strength are a defining morphological trait for the genus Solanum. Anthers arranged in a robust ('pepper pot') cone are restricted to a single clade within the genus, and may therefore be assumed to be monophyletic. We show that in some species within this clade, such as tomato (Solanum lycopersicum), the anther cone is held together by interlocking hairs (trichomes) along the edges of the anthers. In other species within the clade, such as woody nightshade (Solanum dulcamara), the expanded anther surfaces are closely appressed to form the tightly bound cone, strengthened by extracellular secretions. Ectopic expression of the MIXTA gene from Antirrhinum majus in S. dulcamara results in the formation of ectopic trichomes on the anthers which cause the cone to disintegrate. Therefore, these two species produce the same macroscopic structure through two mutually exclusive developmental routes and the robust anther cone is derived differently within the clade. This example demonstrates that convergence between closely related species can be easily mistaken for homology, and may thus be underestimated.

Adaptation, Physiological↗
PubMed1984

Tissue specificity of the heat-shock response in maize.

The tissue specificity of the heat-shock response in maize was investigated. The ability to synthesize heat shock proteins (hsp) at 40 degrees C, as well as the intensity and duration of that synthesis, was analyzed in coleoptiles, scutella, green and etiolated leaves, suspension-cultured cells, germinating pollen grains, and primary root sections at different stages of development. One-dimensional sodium dodecyl sulfate gel electrophoresis of extracted proteins revealed that most of the tissues synthesized the typical set of 10 hsp, but that the exact characteristics of the response depended upon the tissue type. While elongating portions of the primary root exhibited a strong heat shock response, the more mature portions showed a reduced ability to synthesize hsp. Leaves, whether green or etiolated, excised or intact, constitutively synthesized a low level of hsp at 25 degrees C, and high levels could be induced at 40 degrees C. Suspension-cultures of Black Mexican sweet corn synthesized, besides the typical set of hsp, two additional polypeptides. In contrast to all the other tissues, germinating pollen grains could not be induced to synthesize the typical set of hsp but did synthesize two new polypeptides of 92 and 56 kD molecular weight.The heat shock response was transient for most of the tissues which synthesized the standard set of hsp. Hsp synthesis was detected up to 2 to 3 hours, but not at 10 hours of continuous 40 degrees C treatment. The exception was suspension cultured cells, in which hsp synthesis showed only a slight reduction after 10 hours at 40 degrees C. Tissue-specific differences in the heat-shock response suggest that there are differences in the way a given tissue is able to adapt to high temperature.We have confirmed the previous suggestion that maize hsp do not accumulate in substantial quantities. Using two-dimensional gel analysis, hsp could be detected by autoradiography but not by sensitive silver staining techniques.

Journal Article↗
PubMed2006

Rhinitis symptoms and IgE sensitization as risk factors for development of later allergic rhinitis in adults.

BACKGROUND: Rhinitis symptoms and IgE-sensitization often mismatch. Asymptomatic sensitization is an established risk factor for later rhinitis, whereas it is not clear whether rhinitis is a risk factor for later development of IgE-sensitization. OBJECTIVE: To investigate whether nonallergic rhinitis is a risk factor for later development of IgE-sensitization in adults during an 8-year follow-up period, and whether asymptomatic sensitization is a risk factor for later development of rhinitis. METHODS: In a population-based study of 15-69 years olds in 1990, 734 subjects were re-examined in 1998. On both occasions questionnaires on rhinitis symptoms were completed and serum IgE (against birch, grass, mugwort, cat, dog, and Dermatophagoides pteronyssinus) were determined (positive if >or=0.35 kUA/l). Asymptomatic sensitization: positive IgE levels without any rhinitis symptoms. Nonallergic rhinitis: rhinitis symptoms and no sensitization. RESULTS: Asymptomatic sensitization to pollens, pets, or house dust mite was significantly associated with onset of rhinitis symptoms, also when changing baseline cut-off for sensitization to >or=0.1 or >or=0.7 kUA/l. The 8-year incidence of pollen-related rhinitis was 15.1% and 2.6% in subjects sensitized and nonsensitized to pollens, respectively (odds ratio 6.1, 95% CI 2.3-16.0). Persistent or intermittent nonallergic rhinitis was not significantly associated with later sensitization, yet a positive trend for development was observed in nonallergic pollen-related rhinitis. CONCLUSION: Asymptomatic sensitization but not nonallergic rhinitis was a significant risk factor for later development of allergic rhinitis.

Adolescent↗