Hereditary hemochromatosis genetic testing of at-risk children: what is the appropriate age?

The objective of this study was to consider the objective evidence and ethical arguments for the appropriate age to test children at risk of developing hereditary hemochromatosis. A literature search for information on iron overload in children, onset of disease expression for hemochromatosis, and recommendations for age of cascade screening was undertaken. We examined the objective evidence and arguments for testing in early childhood and those for delaying testing until later teenage years. Cascade testing of offspring of people with hemochromatosis is widely advocated because it is an easily preventable disease. The ideal age to test those offspring is a matter of debate. Some authorities advocate testing at a very young age whereas others recommend delaying testing until late teenage years. To date there has been no published overview of the objective evidence and arguments central to this debate. In children who are C282Y homozygous, iron overload is rare in the first two decades of life and associated morbidity has only been documented in 1 patient. In the cascade setting, genetic testing for hemochromatosis need not be offered until late teenage years.     

A data management system for structural genomics

Background  

Structural genomics (SG) projects aim to determine thousands of protein structures by the development of high-throughput techniques for all steps of the experimental structure determination pipeline. Crucial to the success of such endeavours is the careful tracking and archiving of experimental and external data on protein targets.     

F-actin capping (CapZ) and other contractile saphenous vein smooth muscle proteins are altered by hemodynamic stress: a proteonomic approach

Increased force generation and smooth muscle remodeling follow the implantation of saphenous vein as an arterial bypass graft. Previously, we characterized and mapped 129 proteins in human saphenous vein medial smooth muscle using two-dimensional (2-D) PAGE and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Here, we focus on actin filament remodeling in response to simulated arterial flow. Human saphenous vein was exposed to simulated venous or arterial flow for 90 min in vitro, and the contractile medial smooth muscle was dissected out and subjected to 2-D gel electrophoresis using a non-linear immobilized pH 3-10 gradient in the first dimension. Proteins were analyzed quantitatively using PDQuest 2-D software. The actin polymerization inhibitor cytochalasin B (1 microm) prevented increases in force generation after 90 min of simulated arterial flow. At this time point, there were several consistent changes in actin filament-associated protein expression (seven paired vein samples). The heat shock protein HSP27, identified as a three-spot charge train, showed a 1.6-fold increase in abundance (p = 0.01), but with reduced representation of the phosphorylated Ser(82) and Ser(15)Ser(82) isoforms (p = 0.018). The abundance of actin-capping protein alpha2 subunit CapZ had decreased 3-fold, p = 0.04. A 19-kDa proteolytic fragment of actin increased 2-fold, p = 0.04. For the four-spot charge train of gelsolin, there was reduced representation of the more acidic isoforms, p = 0.022. The abundance of other proteins associated with actin filaments, including cofilin and destrin, remained unchanged after arterial flow. Actin filament remodeling with differential expression and/or post-translational modification of proteins involved in capping the barbed end of actin filaments, HSP27 and CapZ, is an early response of contractile saphenous vein smooth muscle cells to hemodynamic stress. The observed changes would favor the generation of contractile stress fibers.     

Extreme difference in rate of mitochondrial and nuclear DNA evolution in a large ectotherm, Galápagos tortoises

We sequenced approximately 4.5 kb of mtDNA from 161 individuals representing 11 named taxa of giant Galápagos tortoises (Geochelone nigra) and about 4 kb of non-coding nuclear DNA from fewer individuals of these same 11 taxa. In comparing mtDNA and nucDNA divergences, only silent substitutions (introns, ITS, mtDNA control region, and synonymous substitutions in coding sequences) were considered. mtDNA divergence was about 30 times greater than that for nucDNA. This rate discrepancy for mtDNA and nucDNA is the greatest yet documented and is particularly surprising for large ectothermic animals that are thought to have relatively low rates of mtDNA evolution. This observation may be due to the somewhat unusual reproductive biology and biogeographic history of these organisms. The implication is that the ratio of effective population size of nucDNA/mtDNA is much greater than the usually assumed four. The nearly neutral theory of molecular evolution predicts this would lead to a greater difference between rates of evolution.     

Copulatory courtship signals male genetic quality in cucumber beetles

In the spotted cucumber beetle, Diabrotica undecimpunctata howardi (Coleoptera: Chrysomelidae), males court females during copulation by stroking them with their antennae. Stroking occurs exclusively during the first stages of copulation, after a male has penetrated a female's vaginal duct but before he is allowed access to her bursa copulatrix. Females accept the spermatophore of fast-stroking males and reject those of slow-stroking males by relaxing or constricting muscles distorting the vaginal duct. Here, we measure the repeatability of stroking behaviour within males, examine the effect of losing one antenna on male attractiveness and test whether such female control results in direct phenotypic benefits for the discriminating female or indirect genetic benefits that appear in her offspring. We also use a half-sibling design to quantify the variance and heritability of stroking speed and endurance. Female beetles were paired with a male that was known to stroke either quickly or slowly. No difference was found in the resulting fecundity or egg-hatching rate of the females, or in the survivorship, development rate, size, age at first reproduction or fecundity of their offspring indicating that no direct benefits are gained by discriminating among males on the basis of stroking speed. There were, however, good-genes benefits for the mates of fast-stroking males. Offspring of fast-stroking fathers were also fast strokers and were more likely to be accepted as mates than offspring of slow-stroking fathers. There was substantial variance among sires in stroking speed and endurance and the heritability of each trait was high. The antennal stroking rate was highly repeatable in successive mating attempts and males with only one antenna were not accepted as mates. The repeatability within males, variability between males and heritability between generations of copulatory stroking combine to provide females with a reliable and honest signal of the genetic quality of courting males.     

Isofurans,but not F2-isoprostanes,are increased in the substantia nigra of patients with Parkinson's disease and with dementia with Lewy body disease

F2-isoprostanes (F2-IsoPs) are well-established sensitive and specific markers of oxidative stress in vivo. Isofurans (IsoFs) are also products of lipid peroxidation, but in contrast to F2-IsoPs, their formation is favored when oxygen tension is increased in vitro or in vivo. Mitochondrial dysfunction in Parkinson's disease (PD) may not only lead to oxidative damage to brain tissue but also potentially result in increased intracellular oxygen tension, thereby influencing relative concentrations of F2-IsoPs and IsoFs. In this study, we attempted to compare the levels of F2-IsoPs and IsoFs esterified in phospholipids in the substantia nigra (SN) from patients with PD to those of age-matched controls as well as patients with other neurodegenerative diseases, including dementia with Lewy body disease (DLB), multiple system atrophy (MSA), and Alzheimer's disease (AD). The results demonstrated that IsoFs but not F2-IsoPs in the SN of patients with PD and DLB were significantly higher than those of controls. Levels of IsoFs and F2-IsoPs in the SN of patients with MSA and AD were indistinguishable from those of age-matched controls. This preferential increase in IsoFs in the SN of patients with PD or DLB not only indicates a unique mode of oxidant injury in these two diseases but also suggests different underlying mechanisms of dopaminergic neurodegeneration in PD and DLB from those of MSA.     

Heat shock protein 27 controls apoptosis by regulating Akt activation

Activation of the serine-threonine kinase Akt by cytokines, chemokines, and bacterial products delays constitutive neutrophil apoptosis, resulting in a prolonged inflammatory response. We showed previously that Akt exists in a signaling complex with p38 MAPK, MAPK-activated protein kinase-2 (MAPKAPK-2), and heat shock protein-27 (Hsp27); and Hsp27 dissociates from the complex upon neutrophil activation. To better understand the regulation of this signaling module, the hypothesis that Akt phosphorylation of Hsp27 regulates its interaction with Akt was tested. The present study shows that Akt phosphorylated Hsp27 on Ser-82 in vitro and in intact cells, and phosphorylation of Hsp27 resulted in its dissociation from Akt. Additionally, the interaction between Hsp27 and Akt was necessary for activation of Akt in intact neutrophils. Constitutive neutrophil apoptosis was accelerated by sequestration of Hsp27 from Akt, and this enhanced rate of apoptosis was reversed by introduction of constitutively active recombinant Akt. Our results define a new mechanism by which Hsp27 regulates apoptosis, through control of Akt activity.     

Modeling the response of the Mediterranean fruit fly (Diptera:Tephritidae) to cold treatment

Recent interceptions of live Mediterranean fruit fly, Ceratitis capitata (Wiedemann), larvae in fruit that had been cold-treated during transit from abroad led to a reevaluation of the scientific basis for the relevant regulatory treatment schedules. A time-temperature response surface model based on the original experimental data from 1916 was developed and evaluated based on subsequent experimental trials and recent surveillance data collected from shipping operations. The resultant model is reasonably robust and supports the conclusion that the previous treatment schedule falls short of the intended probit nine level of security. Given the vintage of the data, methodological inconsistencies among studies, and the potential consequences of new introductions, additional research is warranted. Quantitative analysis of the currently available data suggests that future studies regarding the efficacy of cold storage should focus on low-temperature, short-duration treatments, where uncertainty about performance appears greatest. The analysis of subsequent experiments also demonstrates that for cold treatment trials most often resulting in zero survivors, Bayesian statistical methods applied to a series of replicated trials of more manageable size offers a feasible alternative to conducting impracticably large trials.