The S-locus specific glycoproteins of Brassica accumulate in the cell wall of developing stigma papillae

Self-incompatibility in Brassica oleracea is now viewed as a cellular interaction between pollen and the papillar cells of the stigma surface. In this species, the inhibition of self-pollen occurs at the stigma surface under the influence of S-locus specific glycoproteins (SLSG). We used antibodies specific for a protein epitope of SLSG to study the subcellular distribution of these molecules in the stigmatic papillae. The antibodies have uncovered an interesting epitope polymorphism in SLSG encoded by subsets of S-alleles, thus providing us with useful genetic controls to directly verify the specificity of the immunolocalization data. Examination of thin sections of Brassica stigmas following indirect immunogold labeling showed that SLSG accumulate in the papillar cell wall, at the site where inhibition of self-pollen tube development has been shown to occur. In addition, the absence of gold particles over the papillar cell walls in the immature stigmas of very young buds, and the intense labeling of these walls in the stigmas of mature buds and open flowers, correlates well with the acquisition of the self-incompatibility response by the developing stigma.     

Biosynthesis of glycoproteins involved in the pollen-stigma interaction of incompatibility in developing flowers of Brassica oleracea L.

De-novo synthesis of the S-allele-specific glycoproteins of Brassica oleracea is demonstrated in stigmas at different developmental stages. Excised stigmas incorporate ¹⁴C-labeled amino acids into their S-glycoproteins early in development and before the self-incompatibility response is acquired, but the rate of synthesis accelerates prior to anthesis, resulting in the accumulation of high levels of the S-glycoproteins in the stigma and coinciding with the acquisition of the pollen-stigma incompatibility response. Since the self-compatible and self-incompatible zones of developing inflorescences are very sharply delineated, a threshold quantity of S-glycoproteins appears to be critical for the onset of self-incompatibility. Incorporation experiments in which [^35Smethionine was applied to intact stigma surfaces indicate that the papillae are the main sites of synthesis of the S-specific glycoproteins.Abbreviations IEF isoelectric focusing - SC self-compatibility - SDS sodium dodecyl sulfate - SI self-incompatibility     

Genetic Variants of Angiotensin-Converting Enzyme Are Linked to Autism: A Case-Control Study

BackgroundAutism is a disease of complex nature with a significant genetic component. The importance of renin-angiotensin system (RAS) elements in cognition and behavior besides the interaction of angiotensin II (Ang II), the main product of angiotensin-converting enzyme (ACE), with neurotransmitters in CNS, especially dopamine, proposes the involvement of RAS in autism. Since the genetic architecture of autism has remained elusive, here we postulated that genetic variations in RAS are associated with autism.MethodsConsidering the relation between the three polymorphisms of ACE (I/D, rs4343 and rs4291) with the level of ACE activity, we have investigated this association with autism, in a case-control study. Genotype and allele frequencies of polymorphisms were determined in DNAs extracted from venous blood of 120 autistic patients and their age and sex-matched healthy controls, using polymerase chain reaction (PCR) and PCR–restriction fragment length polymorphism (PCR–RFLP) methods.ResultsThere were strong associations between both DD genotype of ACE I/D and the D allele, with autism (P = 0.006, OR = 2.9, 95% CI = 1.64–5.13 and P = 0.006, OR = 2.18, 95% CI = 1.37–3.48 respectively). Furthermore, a significant association between the G allele of rs4343 and autism was observed (P = 0.006, OR = 1.84, 95%CI = 1.26–2.67). Moreover, haplotype analysis revealed an association between DTG haplotype and autism (P = 0.008).ConclusionOur data suggests the involvement of RAS genetic diversity in increasing the risk of autism.     

The taste of polycose in hamsters

Hamsters show a preference for Polycose, a mixture of starch-derived glucose polymers, that is as strong as their preference for sucrose. However, in the hamster, taste aversions to Polycose may be less easily acquired than taste aversions to sucrose and the qualitative aspects of Polycose are unknown in this species. In order to examine the taste of Polycose in the hamster, we utilized a taste-aversion protocol with two conditioning trials. Animals were trained to avoid one of three different conditioning stimuli: 50 mM sucrose, 100 mM Polycose and a mixture of 50 mM sucrose with 100 mM Polycose. Control animals were conditioned with deionized water. After the second conditioning trial, generalization testing began for the three conditioning stimuli plus 3 mM citric acid, 300 mM KCI and 30 mM NaCl. The results showed that aversions to Polycose, sucrose or the Polycose/sucrose mixture cross- generalized, demonstrating that Polycose and sucrose share a common taste percept in the hamster. None of the aversions generalized to NaCl, citric acid or KCI. In addition, comparisons among the patterns of taste generalizations indicated that the tastes of Polycose and sucrose also had distinct qualitative components. Finally, although the taste of 100 mM Polycose was more salient than the taste of 50 mM sucrose, the taste of sucrose could still be detected in a mixture with Polycose.      

Comparative mapping of the Brassica S locus region and its homeolog in Arabidopsis. Implications for the evolution of mating systems in the Brassicaceae.

The crucifer family includes self-incompatible genera, such as Brassica, and self-fertile genera, such as Arabidopsis. To gain insight into mechanisms underlying the evolution of mating systems in this family, we used a selective comparative mapping approach between Brassica campestris plants homozygous for the S8 haplotype and Arabidopsis. Starting with markers flanking the self-incompatibility genes in Brassica, we identified the homeologous region in Arabidopsis as a previously uncharacterized segment of chromosome 1 in the immediate vicinity of the ethylene response gene ETR1. A total of 26 genomic and 21 cDNA markers derived from Arabidopsis yeast artificial and bacterial artificial chromosome clones were used to analyze this region in the two genomes. Approximately half of the cDNAs isolated from the region represent novel expressed sequence tags that do not match entries in the DNA and protein databases. The physical maps that we derived by using these markers as well as markers isolated from bacteriophage clones spanning the S8 haplotype revealed a high degree of synteny at the submegabase scale between the two homeologous regions. However, no sequences similar to the Brassica S locus genes that are known to be required for the self-incompatibility response were detected within this interval or other regions of the Arabidopsis genome. This observation is consistent with deletion of self-recognition genes as a mechanism for the evolution of autogamy in the Arabidopsis lineage.     

SRK, the stigma-specific S locus receptor kinase of Brassica, is targeted to the plasma membrane in transgenic tobacco.

The S locus receptor kinase (SRK) gene is one of two S locus genes required for the self-incompatibility response in Brassica. We have identified the product of the SRK6 gene in B. oleracea stigmas and have shown that it has characteristics of an integral membrane protein. When expressed in transgenic tobacco, SRK6 is glycosylated and targeted to the plasma membrane. These results provide definitive biochemical evidence for the existence in plants of a plasma membrane-localized transmembrane protein kinase with a known cell-cell recognition function. The timing of SRK expression in stigmas follows a time course similar to that previously described for another S locus-linked gene, the S locus glycoprotein (SLG) gene, and correlates with the ability of stigmas to mount a self-incompatibility response. Based on SRK6 promoter studies, the site of gene expression overlaps with that of SLG and exhibits predominant expression in the stigmatic papillar cells. Although reporter gene studies indicated that the SRK promoter was active in pollen, SRK protein was not detected in pollen, suggesting that SRK functions as a cell surface receptor exclusively in the papillar cells of the stigma.     

SUPRAVALVULAR PULMONARY STENOSIS IN LEVO TRANSPOSITION AND "SINGLE" VENTRICLE

A case of supravalvular and valvular pulmonary stenosis in an L-transposition of the great arteries and "single" or double inlet left ventricle is described. Supravalvular pulmonary stenosis has not heretofore been reported in transposition of the great arteries. The clinical, hemodynamic and angiographic features are described. Surgical correction has many problems.     

Immunodetection of protein glycoforms encoded by two independent genes of the self-incompatibility multigene family of brassica

Glycoprotein products of two highly homologous Brassica S gene family members were studied: SLSG (S locus-specific glycoprotein), product of an SLG gene at the S locus, and SLR1 (S locus-related) protein, product of the SLR1 gene, a gene unlinked to the S locus. A polyclonal antibody directed against a trpE-SLR1 fusion protein facilitated study of the SLR1 protein. SLR1 protein was detected in a number of crucifer species. No variation in the level of this protein was found between self-compatible and self-incompatible plants. Both SLSG and SLR1 protein occurred as glycoforms on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels. Each glycoform had several charge forms, indicated by elution patterns from a high performance liquid chromatography cation exchange column and behavior on two-dimensional gels. Deglycosylation of both SLSG and SLR1 protein caused loss of the glycoforms, which apparently arose from differences in glycosylation. Consistent with their apparent similar post-translational processing, immunolocalization showed that SLR1 protein, like SLSG, accumulated in the stigma papillae cell walls. Thus, both SLSG and SLR1 protein are present at the site of pollen-stigma interaction.