Developmental and behavioural phenotype in Noonan syndrome?

Developmental and behavioural phenotype in Noonan syndrome? Noonan syndrome is characteristic by facial dysmorphology, congenital heart defects, short stature, developmental retardation and severe early feeding disorders in many cases. Data from a postal survey on physical development, feeding difficulties, developmental problems and behavioural aspects in 26 children are reported. The findings suggest developmental and behavioural difficulties in 46 per cent, but do not support the notion of a behavioural phenotype specific to Noonan syndrome. Having to cope with early surgery, feeding, developmental and behavioural problems establishes a need for psychological counseling for families receiving a diagnosis of Noonan syndrome.     

Are flower-visiting ants mutualists or antagonists? A study in a gynodioecious wild strawberry

Ants are common flower visitors, but their effects on plant reproductive fitness have not often been assessed. Flower-visiting ants were studied to determine whether they are antagonists or mutualists and whether they could influence floral or breeding system evolution in gynodioecious wild strawberry (Fragaria virginiana). Ant and flying pollinator (bees/flies) access to plants was manipulated, and visitation, fruit, and seed set were assessed. Ants visited flowers of hermaphrodites more often than those of females when bees and flies were excluded, but visited the sex morphs equally when they were present. Insect class did not influence fruit or seed set of hermaphrodites. In contrast, ants had both positive and negative effects on seed set in females. Females visited only by ants had 90% of the seed set of those visited only by bees/flies, and their seed set increased with ant visitation. The spatial pattern of seed set, however, suggests that ants may also damage pistils. Lastly, in contrast to bees and flies, ants failed to increase visitation with floral display size, suggesting that ant presence at flowers could reduce selection on this attractive trait. Findings suggest that when in high abundance, flower-visiting ants could affect breeding system and floral evolution in this gynodioecious plant.     

Combined klinefelter-Down syndrome or XXYY syndrome?

Summary A case of 48,XXYY constellation is described to demonstrate that both the fluorescence-banding technique and the papillar pattern allow a clear differential diagnosis from the 48,XXY,G+ syndrome, regardless of the clinical appearance.

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Zusammenfassung An Hand eines Falles von 48,XXYY-Konstellation wird demonstriert, daß sowohl die Fluoresenzbandentechnik als auch der Hautleistenbefund eine sichere Differentialdiagnose zum 48,XXY,G+-Syndrom, unabhängig vom klinischen Erscheinungsbild, erlauben.

     

Queen pheromones in Temnothorax ants: control or honest signal?

Background  

The division of reproductive labor among group members in insect societies is regulated by "queen pheromones". However, it remains controversial whether these are manipulative, i.e., actively suppress worker reproduction, or honestly signal the fertility status of the queen to which workers react in their own interest by refraining from laying eggs. Manipulative queen control is thought to lead to an evolutionary arms race between queens and workers, resulting in complex queen bouquets that diverge strongly among different populations and species. In contrast, honest signals would evolve more slowly and might therefore differ less strongly within and among species.     

Can ants be used as ecological indicators of restoration progress in dynamic environments? A case study in a revegetated riparian zone

Ant assemblages are focal ecological indicators of progress in mine-site restoration, often showing increasing species richness with restoration age. Certain functional groups also behave in predictable ways in response to disturbance and changes in the environment. Whether these ant responses can be applied to other types of restoration and ecosystems is unknown, especially in dynamic environments and where gradients may not be as severe as in mine-site restoration. Ant assemblages would be expected to perform poorly as ecological indicators in dynamic environments because such environs are subject to periodic disturbance of important habitat features. Indeed, periodic disturbance may limit the predictive power of any ecological indicator. In this study, we trapped ants on two separate occasions to compare ant assemblages among four riparian habitat types (Unplanted grassland, Young revegetation, Older revegetation and Mature woodland). These habitat types were assumed to represent progressive stages of restoration. In contrast to the findings of others, species richness was variable among replicate locations of the same habitat type, and did not differ among the four habitat types. Also in contrast to what others have found for functional groups, dolichoderines were equally abundant in all habitat types and did not decrease in abundance with vegetation maturity. While generalized myrmicines and opportunists became more common with maturation of the vegetation, they did not replace dolichoderines as the most common ants. Surprisingly, the relative abundance of Subordinate Camponotini, a functional group considered to be of limited use in discriminating structural types, increased across the restoration gradient. There were also fairly distinct species assemblages associated with unplanted grassland and mature woodland. Communities in revegetated habitats were intermediate of these extremes, suggesting there is a level of predictiveness to their response to revegetation in this system. While species richness and a functional group approach would be of little use in this environment, species composition would provide a useful gauge of restoration progress. Ant species richness and functional group metrics have repeatedly been advocated as ecological indicators. Given our results, we caution against the blind application of metrics that have not been validated in the context in which they are to be applied.     

To be folded or to be unfolded?

The lack of ordered structure in “natively unfolded” proteins raises a general question: Are there intrinsic properties of amino acid residues that are responsible for the absence of fixed structure at physiological conditions? In this article, we demonstrate that the competence of a protein to be folded or to be unfolded may be determined by the property of amino acid residues to form a sufficient number of contacts in a globular state. The expected average number of contacts per residue calculated from the amino acid sequence alone (using the average number of contacts for 20 amino acid residues in globular proteins) can be used as one of the simple indicators of natively unfolded proteins. The prediction accuracy for the sets of 80 folded and 90 natively unfolded proteins reaches 89% if the expected average number of contacts is used as a parameter and 83% in the case of hydrophobicity. An optimal set of artificial parameters for 20 amino acid residues obtained by Monte Carlo algorithm to maximally separate the sets of 90 natively unfolded and 80 folded proteins demonstrates the upper limit for prediction accuracy, which is 95%.     

Neotyphodium endophytes in grasses: deterrents or promoters of herbivory by leaf-cutting ants?

Endophytic fungi, particularly in the genus Neotyphodium, are thought to interact mutualistically with host grasses primarily by deterring herbivores and pathogens via production of alkaloidal mycotoxins. Little is known, however, about how these endophytes interact with host plants and herbivores outside the realm of agronomic forage grasses, such as tall fescue, and their livestock grazers or invertebrate pest herbivores. We tested the effects of Neotyphodium inhabiting introduced tall fescue and native Arizona fescue on preference, survival, and performance of the leaf-cutting ant, Acromyrmex versicolor, an important generalist herbivore in the southwestern United States. In a choice experiment, we determined preferences of foraging queens and workers for infected and uninfected tall fescue and Arizona fescue. In a no-choice experiment, we determined queen survival, worker production, and size of fungal gardens for foundress queens reared on diets of infected and uninfected tall fescue and Arizona fescue. Foraging workers and queens did not significantly prefer either uninfected tall fescue or Arizona fescue relative to infected grasses, although ants tended to harvest more uninfected than infected tall fescue and more infected than uninfected Arizona fescue. Queen survivorship and length of survival was greater on uninfected tall fescue, uninfected Arizona fescue, and infected Arizona fescue than on infected tall fescue or the standard diet of palo verde and mesquite leaves. No queens survived beyond 6 weeks of the study when fed the infected tall fescue diet, in contrast to the effects of the other diets. Likewise, worker production was much lower and fungal garden size much smaller on infected tall fescue than in all other treatments, including the standard diet. In general, ant colonies survived and performed better on uninfected tall fescue and infected and uninfected Arizona fescue than standard diets of palo verde and mesquite leaves. The interaction of Neotyphodium with its host grasses is highly variable and these endophytes may increase, not alter, or even decrease resistance to herbivores. The direction of the interaction depends on host and fungal genotype, herbivore species, and environmental factors. The presence of endophytes in most, if not all, host plants suggests that endophytes may alter foraging patterns, performance, and survival of herbivores, such as leaf-cutting ants, but not always in ways that increase host plant fitness. Received: 27 October 1998 / Accepted: 19 October 1998     

McKusick-Kaufman or Bardet-Biedl syndrome? A new borderline case in an Italian nonconsanguineous healthy family

McKusick-Kaufman syndrome (MKS, OMIM #236700) is a rare syndrome inherited in an autosomal recessive pattern with a phenotypic triad comprising hydrometrocolpos (HMC), postaxial polydactyly (PAP), and congenital cardiac disease (CHD). The syndrome is caused by mutations in the MKKS gene mapped onto chromosome 20p12 between D20S162 and D20S894 markers. Mutations in the same gene causes Bardet-Biedl-6 syndrome (BBS-6, OMIM #209900) inherited in an autosomal recessive pattern. BBS-6 comprises retinitis pigmentosa, polydactyly, obesity, mental retardation, renal and genital anomalies. HMC, CHD, and PAP defects can also occur in BBS-6, and there is a significant clinical overlap between MKS and BBS-6 in childhood. We describe a new borderline case of MKS and BBS syndrome and suggest insights for understanding correlation between MKKS gene mutations and clinical phenotype. Here, we report the results of molecular analysis of MKKS in a female proband born in an Italian nonconsanguineous healthy family that presents HMC and PAP. The mutational screening revealed the presence of two different heterozygous missense variants (p.242A>S in exon 3, p.339 I>V in exon 4) in the MKKS gene, and a nucleotide variation in 5'UTR region in exon 2 (-417 A>C).     

To be or not to be ubiquitinated?

Levels of p21, a cyclin-dependent kinase (CDK) inhibitor, are controlled in part at the post-translational level by protein degradation. Although the signaling pathways leading to p21 degradation have not yet been fully elucidated, it is evident that p21 ubiquitination is an essential factor in its degradation. We discuss that, with the only notable exception of ornithine decarboxylase, ubiquitination appears to be a prerequisite for proteasomal degradation rather than an unnecessary byproduct of such proteolysis.     

A role for phytotoxins in thePhragmites die-back syndrome?

Die-back and healthy stands ofPhragmites australis (Cav.) Trin. exSteud., in the U.K. and Hungary, were compared in terms of plant morphology and anatomy, sediment redox potential and sulphide levels and plant resistance to internal Poiseuille gas flow. In laboratory experiments rhizome cuttings were exposed to acetic acid or dissolved sulphide in unstirred solution cultures in order to determine whether the die-back symptoms found in the field could be induced by these phytotoxins. Most of the die-back symptoms, namely stunting of adventitious roots and laterals, bud death, callus blockages of the gas-pathways, and vascular blockages (both xylem and phloem), were produced by each of the phytotoxin treatments. These symptoms were largely absent from healthy field sites and from the experimental controls. In a greenhouse experiment, plants were grown in waterlogged sand or loam, with or without a sub-surface organic layer composed of chopped up rhizomes and roots mixed with the soil base. Especially during the first 70 days, redox levels were considerably lowered, and shoot numbers and shoot growth much reduced by the presence of the organic layers; the effects were most pronounced in the sand plus organic matter treatment. It is suggested that accumulated phytotoxins, e.g. orgnaic acids and/or sulphide, whether produced from the death and decay of the plant, or from excessive organic loading or as an indirect results of eutrophication, will perpetuate the die-back ofPhragmites and prevent the recovery of the plant in the short term.     

Free radicals in chronic fatigue syndrome: cause or effect?

Abstract

We have demonstrated that certain morphological and biochemical changes occur in chronic fatigue syndrome (CFS) and in rheumatoid arthritis (RA). These changes in RA can be explained by the well-established inappropriate increase in free radical generation. The similar changes in CFS suggest a similar explanation and a possible role for free radicals in the aetiology of this condition.