Bullying Victimization, Parenting Stress, and Anxiety among Adolescents and Young Adults with Autism Spectrum Disorder.

Bullying victimization is commonly associated with anxiety among individuals with and without Autism Spectrum Disorder (ASD), and both bullying victimization and anxiety are more prevalent among youth with ASD than in the general population. We explored individual and contextual factors that relate to anxiety in adolescents and young adults with ASD who also experience bullying victimization. Participants included 101 mothers of adolescents and young adults diagnosed with ASD. Hierarchical multiple regression analyses were conducted to investigate the relationship between bullying victimization and anxiety in children with ASD, as well as parenting stress as a potential moderator of that relationship. Findings indicate that parenting stress moderates the association between bullying victimization and anxiety. The severity of anxiety was most strongly associated with bullying victimization when mothers reported high levels of stress. Implications for interventions that assist parents with coping and address bullying victimization are discussed.

Shedding light on a pervasive problem: a review of research on bullying experiences among children with autism spectrum disorders.

Autism spectrum disorders (ASD) are characterized by difficulties with social interaction, verbal and nonverbal communication, and the development and maintenance of interpersonal relationships. As a result, individuals with ASD are at an increased risk of bullying victimization, compared to typically developing peers. This paper reviews the literature that has emerged over the past decade regarding prevalence of bullying involvement in the ASD population, as well as associated psychosocial factors. Directions for future research are suggested, including areas of research that are currently unexplored or underdeveloped. Methodological issues such as defining and measuring bullying, as well as informant validity and reliability, are considered. Implications for intervention are discussed.

The impact of child problem behaviors of children with ASD on parent mental health: the mediating role of acceptance and empowerment.

Raising a child with an autism spectrum disorder (ASD) has often been associated with higher levels of parenting stress and psychological distress, and a number of studies have examined the role of psychological processes as mediators of the impact of child problem behavior on parent mental health. The current study examined the relations among child problem behavior, parent mental health, psychological acceptance, and parent empowerment. Participants included 228 parents of children diagnosed with ASD, 6-21 years of age. As expected, psychological acceptance and empowerment were negatively related to the severity of parent mental health problems. When acceptance and empowerment were compared with each other through a test of multiple mediation, only psychological acceptance emerged as a significant partial mediator of the path between child problem behavior and parent mental health problems. As child problem behavior increased, parent psychological acceptance decreased, resulting in an increase in parent mental health problems. These findings suggest that for problems that are chronic and difficult to address, psychological acceptance may be an important factor in coping for parents of young people with ASD, in line with the growing literature on positive coping as compared with problem-focused coping.

Bullying experiences among children and youth with autism spectrum disorders.

Few studies have investigated bullying experiences among children diagnosed with autism spectrum disorders (ASD); however, preliminary research suggests that children with ASD are at greater risk for being bullied than typically developing peers. The aim of the current study was to build an understanding of bullying experiences among children with ASD based on parent reports by examining rates of various forms of bullying, exploring the association between victimization and mental health problems, and investigating individual and contextual variables as correlates of victimization. Victimization was related to child age, internalizing and externalizing mental health problems, communication difficulties, and number of friends at school, as well as parent mental health problems. Bullying prevention and intervention strategies are discussed.

Contextualizing the neurobiology of conduct disorder in an emotion dysregulation framework.

Conduct disorder (CD) represents the most common childhood psychiatric disorder found in community and mental health clinics. This paper provides a comprehensive review of the neurobiology of CD; specifically, neurological and neurochemical correlates. Converging evidence suggests that neurological profiles of individuals with CD, compared to peers, are characterized by reduced P300 brain wave amplitude, deactivation of the anterior cingulated cortex and reduced activation in the left amygdala in response to negative stimuli, and reduced right temporal lobe volume. The neurochemical profiles of individuals with CD are characterized by reduced serotonin and cortisol levels (i.e., decreased HPA axis function), as well as attenuated autonomic nervous system functioning. Popular theoretical frameworks cited within the CD literature are limited in their ability to explain and consolidate the neurological and neurochemical findings. We believe that emotion dysregulation theory, though not often used within CD research, may provide the most comprehensive and inclusive framework for understanding neurobiological aspects of this disorder. Limitations within the literature, future directions for research, and implications of the findings will be discussed.

Rejection of S-heteroallelic pollen by a dual-specific s-RNase in Solanum chacoense predicts a multimeric SI pollen component.

S-heteroallelic pollen (HAP) grains are usually diploid and contain two different S-alleles. Curiously, HAP produced by tetraploids derived from self-incompatible diploids are typically self-compatible. The two different hypotheses previously advanced to explain the compatibility of HAP are the lack of pollen-S expression and the "competition effect" between two pollen-S gene products expressed in a single pollen grain. To distinguish between these two possibilities, we used a previously described dual-specific S(11/13)-RNase, termed HVapb-RNase, which can reject two phenotypically distinct pollen (P(11) and P(13)). Since the HVapb-RNase does not distinguish between the two pollen types (it recognizes both), P(11)P(13) HAP should be incompatible with the HVapb-RNase in spite of the competition effect. We show here that P(11)P(13) HAP is accepted by S(11)S(13) styles, but is rejected by the S(11/13)-RNase, which demonstrates that the pollen-S genes must be expressed in HAP. A model involving tetrameric pollen-S is proposed to explain both the compatibility of P(11)P(13) HAP on S(11)S(13)-containing styles and the incompatibility of P(11)P(13) HAP on styles containing the HVapb-RNase.

Genotype-dependent differences in S12-RNase expression lead to sporadic self-compatibility.

Sporadic self-compatibility, the occasional fruit formation after otherwise incompatible pollinations, has been observed in some S12-containing genotypes of Solanum chacoense but not in others. We have sequenced this S12 allele and analyzed its expression in four different genotypes. The S12-RNase levels were generally less abundant than those of other S-RNases present in the same plants. In addition, two-fold and five-fold differences in the amount of S12-RNase and S12 RNA, respectively, were observed among the genotypes analyzed. A comparison with the genetic data showed that genotypes with the highest levels were fully and permanently self-incompatible, whereas those with the lowest levels were those in which sporadic self-compatibility had been observed. The mature protein contains four potential glycosylation sites and genotype-specific differences in the pattern of glycosylation are also observed. Our results suggest the presence of modifier genes which affect, in a genotype-dependent manner, the level of expression and the post-translational modification of the S12-RNase.

S-RNase uptake by compatible pollen tubes in gametophytic self-incompatibility.

Many flowering plants avoid inbreeding through a genetic mechanism termed self-incompatibility. An extremely polymorphic S-locus controls the gametophytic self-incompatibility system that causes pollen rejection (that is, active arrest of pollen tube growth inside the style) when an S-allele carried by haploid pollen matches one of the S-alleles present in the diploid style. The only known product of the S-locus is an S-RNase expressed in the mature style. The pollen component to this cell-cell recognition system is unknown and current models propose that it either acts as a gatekeeper allowing only its cognate S-RNase to enter the pollen tube, or as an inhibitor of non-cognate S-RNases. In the latter case, all S-RNases are presumed to enter pollen tubes; thus, the two models make diametrically opposed predictions concerning the entry of S-RNases into compatible pollen. Here we use immunocytochemical labelling of pollen tubes growing in styles to show accumulation of an S-RNase in the cytoplasm of all pollen-tube haplotypes, thus providing experimental support for the inhibitor model.

Production of an S RNase with dual specificity suggests a novel hypothesis for the generation of new S alleles.

Gametophytic self-incompatibility in plants involves rejection of pollen when pistil and pollen share the same allele at the S locus. This locus is highly multiallelic, but the mechanism by which new functional S alleles are generated in nature has not been determined and remains one of the most intriguing conceptual barriers to a full understanding of self-incompatibility. The S(11) and S(13) RNases of Solanum chacoense differ by only 10 amino acids, but they are phenotypically distinct (i.e., they reject either S(11) or S(13) pollen, respectively). These RNases are thus ideally suited for a dissection of the elements involved in recognition specificity. We have previously found that the modification of four amino acid residues in the S(11) RNase to match those in the S(13) RNase was sufficient to completely replace the S(11) phenotype with the S(13) phenotype. We now show that an S(11) RNase in which only three amino acid residues were modified to match those in the S(13) RNase displays the unprecedented property of dual specificity (i.e., the simultaneous rejection of both S(11) and S(13) pollen). Thus, S(12)S(14) plants expressing this hybrid S RNase rejected S(11), S(12), S(13), and S(14) pollen yet allowed S(15) pollen to pass freely. Surprisingly, only a single base pair differs between the dual-specific S allele and a monospecific S(13) allele. Dual-specific S RNases represent a previously unsuspected category of S alleles. We propose that dual-specific alleles play a critical role in establishing novel S alleles, because the plants harboring them could maintain their old recognition phenotype while acquiring a new one.

Hypervariable Domains of Self-Incompatibility RNases Mediate Allele-Specific Pollen Recognition.

Self-incompatibility (SI) in angiosperms is a genetic mechanism that promotes outcrossing through rejection of self-pollen. In the Solanaceae, SI is determined by a multiallelic S locus whose only known product is an S RNase. S RNases show a characteristic pattern of five conserved and two hypervariable regions. These are thought to be involved in the catalytic function and in allelic specificity, respectively. When the Solanum chacoense S12S14 genotype is transformed with an S11 RNase, the styles of plants expressing significant levels of the transgene reject S11 pollen. A previously characterized S RNase, S13, differs from the S11 RNase by only 10 amino acids, four of which are located in the hypervariable regions. When S12S14 plants were transformed with a chimeric S11 gene in which these four residues were substituted with those present in the S13 RNase, the transgenic plants acquired the S13 phenotype. This result demonstrates that the S RNase hypervariable regions control allelic specificity.

A comparison of RFLP maps based on anther culture derived, selfed, and hybrid progenies of Solanum chacoense.

Comparative RFLP linkage maps were constructed using five segregating populations derived from two self-incompatible lines (termed PI 230582 and PI 458314) of diploid tuber-bearing Solanum chacoense Bitt. The analysis was based on 84 RFLP loci identified by 73 different cDNA clones. Distortion of expected Mendelian segregation ratios was observed; less than 10% of the markers showed a skewed segregation in the gametes forming the F1, hybrid population compared with 30% in the selfed population and 46 and 70% in the two populations produced by anther culture. For the anther culture derived populations, most of the skewed loci were scattered throughout the genome, whereas in the populations derived from selfing, they were found primarily in linkage group 1, around the S locus. In this study, we also found that the rate of meiotic recombination could differ between the male and female gametes produced by our parental lines. Thus, male gametes of line PI 458314 showed significantly less recombination as assessed by the total length of the map (206 cM for male gametes vs. 375 cM for female gametes) and the phenomenon was genome-wide. In contrast, the maps from the gametes of PI 230582 had about the same length, but some linkage groups were longer in the female gametes, while others were longer in the male gametes. Key words : Solanum chacoense, RFLP, anther culture, skewed segregation, self-incompatibility, sex differences in recombination.

The starch phosphorylase gene is subjected to different modes of regulation in starch-containing tissues of potato.

Analysis of the levels of starch phosphorylase mRNA and its product in the various organs of the potato plant indicates that the gene is differentially regulated, leading to a high accumulation of the gene product in tubers. The amount of phosphorylase transcripts synthesized in nuclei isolated from tubers and leaves indicates that the difference in the steady-state levels of phosphorylase mRNA in these organs can be explained by different rates of initiation of transcription. However, while rates of initiation of transcription are similar in tubers and stems, the steady-state level of phosphorylase mRNA is much lower in the stem. Transgenic potato plants expressing the beta-glucuronidase (GUS) gene under the control of 5'-flanking sequences of the phosphorylase gene exhibited high levels of GUS activity in petioles, stems, stolons, tubers and roots, but low levels in leaves. This confirms the results of transcription assays observed for leaves, stems and tubers, and indicates that accumulation of phosphorylase mRNA in stems and tubers is not controlled solely by transcription initiation. Finally, histochemical analysis for GUS activity in transgenic potato plants suggests that transcription of the phosphorylase gene predominantly occurs in starch-containing cells associated to vascular tissues, and suggests a role for starch phosphorylase in the mobilization of starch stored along the translocation pathway.

Study of microspore-culture responsiveness in oilseed rape (Brassica napus L.) by comparative mapping of a F2 population and two microspore-derived populations.

RFLP segregation analyses were performed on a F2 population and two F1 microspore-derived populations from the same cross between a microspore culture-responsive parent ('Topas') and a non-responsive parent ('Westar'). A total of 145 loci were detected with 87 cDNA clones. Eighty-two markers were common across all three populations. A total of 66 markers was assembled into 18 linkage groups and 16 markers remained unlinked. Segregation distortions were significant for 29% of the markers in the F2 population and 23% and 31% in microspore-derived populations M3 and M5, respectively. An equivalent number of markers showed biased segregation towards each parental allele in the F2 population while more markers showed a significant deviation from the expected Mendelian ratio towards the responsive parent in both microspore-derived populations. Different subsets of markers showed segregation distortions in the three populations indicating that the selective pressures leading to microsporederived plants are different from those acting during selfing of the F1. Linkage groups 1 and 18 were identified as putative chromosomal regions associated with microspore-culture responsiveness.

RFLP analyses and segregation of molecular markers in plants produced by in vitro anther culture, selfing, and reciprocal crosses of two lines of self-incompatible Solanum chacoense.

RFLP analyses were used to characterize several plant populations of Solanum chacoense Bitt. developed to investigate the generation of new S alleles at the self-incompatibility locus. The plant material consisted of two diploid parental lines, their anther culture derived (AC) progenies, their selfed progenies, and their reciprocal F1 hybrids. The RFLP analyses on the AC plants (121 individuals in total) permitted unambiguous identification of their origin. In particular, a distinction between plants originated from reduced (n) or unreduced (2n) microspores could be made. All the AC plants produced by gametic embryogenesis showed distinct RFLP patterns, whereas a number of clones (i.e., plants with identical RFLP patterns) were found among those regenerated via callus. The analyses conducted on the selfed progenies (69 plants) and the F1 hybrids (66 plants) showed only one case of accidental outcross. Segregation studies of the RFLP markers revealed significant deviations from expected Mendelian ratios in both AC-derived populations, as well as in the selfed progenies. Such deviations, however, were rare in the reciprocal F1 hybrids. These results are discussed in relation to the possible presence of genetic sieves operating during AC, illegitimate selfing, or during normal fertilization.

The S11 and S13 self incompatibility alleles in Solanum chacoense Bitt. are remarkably similar.

A genomic clone of the S11 allele from the self-incompatibility locus (S locus) in Solanum chacoense Bitt. has been isolated by cross-hybridization to the S. chacoense S13 allele and sequenced. The sequence of the S11 allele contains all the features expected for S genes of the Solanaceae, and S11 expression, as assessed by northern blots and RNA-PCR, was similar to that of other S. chacoense S alleles. The S11 protein sequence shares 95% identity with the phenotypically distinct S13 protein of S. chacoense and is the gametophytic S allele with the highest similarity to an existing allele so far discovered. Only 10 amino acid changes differentiate the mature proteins from these two alleles, which sets a new lower limit to the number of changes that can produce an altered S allele specificity. The amino acid substitutions are not clustered, suggesting that an accumulation of random point mutations can generate S allele diversity. The S11 intron is unusual in that it could be translated in frame with the coding sequence, thus suggesting an additional mechanism for the generation of new S alleles.

Genetic control of in vitro shoot regeneration from leaf explants inSolanum chacoense Bitt.

Although the heritable nature of plant tissue culture responses is now well documented in many species, only a few studies have been conducted to elucidate complete inheritance patterns. Genetic control of in vitro shoot regeneration from leaf explants was investigated inSolanum chacoense using parental, F1 and F2 generations. Broad-sense heritability estimates were high for frequency (percentage) of responsive leaf explants (61-83%) and number of shoots regenerated per responsive explant (53-75%). Consistent with high heritability estimates, a hypothesis involving three genes could be formulated to explain the variability in the response observed in this study. This model implies that homozygous recessive alleles at any two (out of three) loci are required for the highest response, i.e., more than two shoots per explant in more than 40% of the explants. The presence of homozygous recessive alleles at any one of the three loci produces an intermediate response, i.e., fewer than 40% of the explants regenerating fewer than two shoots per explant, and a dominant allele at all the three loci results in non-responsiveness. Additional minor modifier genes, each with a small effect, would also be required to account for the variable intensity of regeneration within groups. Such a relatively simple genetic control of in vitro regenerability suggests that incorporation of this trait should be easy in potato improvement programmes.

Tissue printing and its applications in self-incompatibility studies.

In this study, the tissue printing technique has been used to rapidly localize in female tissues the presence of specific mRNA representing the products (or some of the products) of the self-incompatibility S-locus gene(s). The methodology, initially developed for Brassica oleracea (sporophytic self-incompatibility) has been successfully employed on Solanum chacoense (gametophytic self-incompatibility). In the Brassica system tissue printing has allowed rapid discrimination between S alleles belonging to class 1 (dominant types) vs. class 2 (recessive types), and thus parallels findings obtained by restriction analyses. In the Solanum system the level of the S-RNase messages was analysed by scanning laser densitometry, and it was found that the message levels of the allele S14 declined faster than those coming from S13 in mature flowers.

Effects of some growth regulators on in vitro tuberization in Dioscorea alata L. 'Brazo fuerte' and D. abyssinica Hoch.

Nodal cuttings of Dioscorea alata L. 'Brazo fuerte' and D. abyssinica Hoch. were cultured in vitro to assess the influence of NAA on the production of microtubers. In D. alata, high concentrations of NAA (27 and 54 µM) favored the production of large microtubers, whereas the highest number of microtubers was obtained with 2.7 µM. D. abyssinica was found to be more sensitive to NAA since concentrations higher than 0.27 µM promoted the growth of callus on the root system. In this species, the production of the largest microtubers was obtained at 2.7 µM whereas the number of microtubers was not affected by any concentration tested. In D. alata, the effects of ABA and BAP were also evaluated. The weight of the microtubers increased with increasing concentrations of ABA. This effect, however, was observed only on expiants cultured under 8 h photoperiod, but not on those cultured under 16 h. Finally the presence of BAP at concentrations as low as 0.22 µM adversely affected the survival of the explants.

Restriction fragment length polymorphism (RFLP) analyses of plants produced by in vitro anther culture of Solanum chacoense Bitt.

In this study, a novel approach was used to characterize the genetic architecture of plants produced by in vitro anther culture of two lines of self-incompatible Solanum chacoense Bitt. (2n=2x=24). We used cytological observations to determine the ploidy level of the regenerated plants and scanned genomic DNA of the anther donor plants to identify heterozygous sequences. Restriction fragment length polymorphism (RFLP) analyses permitted the visualization of DNA variations. Several heterozygous DNA markers were found within single anther donor plants. Completely homozygous lines could be easily identified. Somatically derived plants could be separated from diploid plants produced from 2n (unreduced) microspores. Our results demonstrate first division restitution (FDR) as the mechanism operating during the production of 2n microspores in one of our S. chacoense line. Potential applications of RFLP analyses for genetic mapping, identification of lethal alleles and quantitative trait loci (QTL) with haploid or homozygous diploid plants and determination of gene-centromere distance with diploid plants derived from 2n microspores will be discussed.