Zinc finger RNA binding protein 2 (ZFR2) is not required for male fertility in the mouse.

BACKGROUND: Thousands of genes are expressed during spermatogenesis and male infertility has a strong genetic component. Within this study, we focus on the role of Zfr2 in male fertility, a gene previously implicated in human male fertility. To date, very little is known about the role of ZFR2 in either humans or mice. To this end, the requirement for ZFR2 in male fertility was assessed using a knockout mouse model. RESULTS: Zfr2 was found to be expressed in the testes of both humans and mice. Deletion of Zfr2 was achieved via removal of exon 2 using CRISPR-Cas9 methods. The absence of Zfr2 did not result in a reduction in any fertility parameters assessed. Knockout males were capable of fostering litter sizes equal to wild type males, and there were no effects of Zfr2 knockout on sperm number or motility. We note Zfr2 knockout females were also fertile. CONCLUSIONS: The absence of Zfr2 alone is not sufficient to cause a reduction in male fertility in mice.

Fear-of-intimacy-mediated zinc transport controls the function of zinc-finger transcription factors involved in myogenesis.

Zinc is a component of one-tenth of all human proteins. Its cellular concentration is tightly regulated because its dyshomeostasis has catastrophic health consequences. Two families of zinc transporters control zinc homeostasis in organisms, but there is little information about their specific developmental roles. We show that the ZIP transporter Fear-of-intimacy (Foi) is necessary for the formation of Drosophila muscles. In foi mutants, myoblasts segregate normally, but their specification is affected, leading to the formation of a misshapen muscle pattern and distorted midgut. The observed phenotypes could be ascribed to the inactivation of specific zinc-finger transcription factors (ZFTFs), supporting the hypothesis that they are a consequence of intracellular depletion of zinc. Accordingly, foi phenotypes can be rescued by mesodermal expression of other ZIP members with similar subcellular localization. We propose that Foi acts mostly as a transporter to regulate zinc intracellular homeostasis, thereby impacting on the activity of ZFTFs that control specific developmental processes. Our results additionally suggest a possible explanation for the presence of large numbers of zinc transporters in organisms based on differences in ion transport specificity and/or degrees of activity among transporters.

In Vivo Modeling of the Pathogenic Effect of Copper Transporter Mutations That Cause Menkes and Wilson Diseases, Motor Neuropathy, and Susceptibility to Alzheimer's Disease.

Copper is an essential biometal, and several inherited diseases are directly associated with a disruption to normal copper homeostasis. The best characterized are the copper deficiency and toxicity disorders Menkes and Wilson diseases caused by mutations in the p-type Cu-ATPase genes ATP7A and ATP7B, respectively. Missense mutations in the C-terminal portion of ATP7A have also been shown to cause distal motor neuropathy, whereas polymorphisms in ATP7B are associated with increased risk of Alzheimer's disease. We have generated a single, in vivo model for studying multiple pathogenic mutations in ATP7 proteins using Drosophila melanogaster, which has a single orthologue of ATP7A and ATP7B. Four pathogenic ATP7A mutations and two ATP7B mutations were introduced into a genomic ATP7 rescue construct containing an in-frame C-terminal GFP tag. Analysis of the wild type ATP7-GFP transgene confirmed that ATP7 is expressed at the basolateral membrane of larval midgut copper cells and that the transgene can rescue a normally early lethal ATP7 deletion allele to adulthood. Analysis of the gATP7-GFP transgenes containing pathogenic mutations showed that the function of ATP7 was affected, to varying degrees, by all six of the mutations investigated in this study. Of particular interest, the ATP7BK832R Alzheimer's disease susceptibility allele was found, for the first time, to be a loss of function allele. This in vivo system allows us to assess the severity of individual ATP7A/B mutations in an invariant genetic background and has the potential to be used to screen for therapeutic compounds able to restore function to faulty copper transport proteins.

Developmental neurotoxicity of the organophosphorus insecticide chlorpyrifos: from clinical findings to preclinical models and potential mechanisms.

Organophosphorus (OP) insecticides are pest-control agents heavily used worldwide. Unfortunately, they are also well known for the toxic effects that they can trigger in humans. Clinical manifestations of an acute exposure of humans to OP insecticides include a well-defined cholinergic crisis that develops as a result of the irreversible inhibition of acetylcholinesterase (AChE), the enzyme that hydrolyzes the neurotransmitter acetylcholine (ACh). Prolonged exposures to levels of OP insecticides that are insufficient to trigger signs of acute intoxication, which are hereafter referred to as subacute exposures, have also been associated with neurological deficits. In particular, epidemiological studies have reported statistically significant correlations between prenatal subacute exposures to OP insecticides, including chlorpyrifos, and neurological deficits that range from cognitive impairments to tremors in childhood. The primary objectives of this article are: (i) to address the short- and long-term neurological issues that have been associated with acute and subacute exposures of humans to OP insecticides, especially early in life (ii) to discuss the translational relevance of animal models of developmental exposure to OP insecticides, and (iii) to review mechanisms that are likely to contribute to the developmental neurotoxicity of OP insecticides. Most of the discussion will be focused on chlorpyrifos, the top-selling OP insecticide in the United States and throughout the world. These points are critical for the identification and development of safe and effective interventions to counter and/or prevent the neurotoxic effects of these chemicals in the developing brain. This is an article for the special issue XVth International Symposium on Cholinergic Mechanisms.

The Drosophila melanogaster phospholipid flippase dATP8B is required for odorant receptor function.

The olfactory systems of insects are fundamental to all aspects of their behaviour, and insect olfactory receptor neurons (ORNs) exhibit exquisite specificity and sensitivity to a wide range of environmental cues. In Drosophila melanogaster, ORN responses are determined by three different receptor families, the odorant (Or), ionotropic-like (IR) and gustatory (Gr) receptors. However, the precise mechanisms of signalling by these different receptor families are not fully understood. Here we report the unexpected finding that the type 4 P-type ATPase phospholipid transporter dATP8B, the homologue of a protein associated with intrahepatic cholestasis and hearing loss in humans, is crucial for Drosophila olfactory responses. Mutations in dATP8B severely attenuate sensitivity of odorant detection specifically in Or-expressing ORNs, but do not affect responses mediated by IR or Gr receptors. Accordingly, we find dATP8B to be expressed in ORNs and localised to the dendritic membrane of the olfactory neurons where signal transduction occurs. Localisation of Or proteins to the dendrites is unaffected in dATP8B mutants, as is dendrite morphology, suggesting instead that dATP8B is critical for Or signalling. As dATP8B is a member of the phospholipid flippase family of ATPases, which function to determine asymmetry in phospholipid composition between the outer and inner leaflets of plasma membranes, our findings suggest a requirement for phospholipid asymmetry in the signalling of a specific family of chemoreceptor proteins.

Reduced glutathione biosynthesis in Drosophila melanogaster causes neuronal defects linked to copper deficiency.

Glutathione (GSH) is a tripeptide often considered to be the master antioxidant in cells. GSH plays an integral role in cellular redox regulation and is also known to have a role in mammalian copper homeostasis. In vitro evidence suggests that GSH is involved in copper uptake, sequestration and efflux. This study was undertaken to further investigate the roles that GSH plays in neuronal copper homeostasis in vivo, using the model organism Drosophila melanogaster. RNA interference-mediated knockdown of the Glutamate-cysteine ligase catalytic subunit gene (Gclc) that encodes the rate-limiting enzyme in GSH biosynthesis was utilised to genetically deplete GSH levels. When Gclc was knocked down in all neurons, this caused lethality, which was partially rescued by copper supplementation and was exacerbated by additional knockdown of the copper uptake transporter Ctr1A, or over-expression of the copper efflux transporter ATP7. Furthermore, when Gclc was knocked down in a subset of neuropeptide-producing cells, this resulted in adult progeny with unexpanded wings, a phenotype previously associated with copper dyshomeostasis. In these cells, Gclc suppression caused a decrease in axon branching, a phenotype further enhanced by ATP7 over-expression. Therefore, we conclude that GSH may play an important role in regulating neuronal copper levels and that reduction in GSH may lead to functional copper deficiency in neurons in vivo. We provide genetic evidence that glutathione (GSH) levels influence Cu content or distribution in vivo, in Drosophila neurons. GSH could be required for binding Cu imported by Ctr1A and distributing it to chaperones, such as Mtn, CCS and Atox1. Alternatively, GSH could modify the copper-binding and transport activities of Atox1 and the ATP7 efflux protein via glutathionylation of copper-binding cysteines.

A fly's eye view of zinc homeostasis: Novel insights into the genetic control of zinc metabolism from Drosophila.

The core zinc transport machinery is well conserved between invertebrates and mammals, with the vinegar fly Drosophila melanogaster having clear homologues of all major groups of mammalian ZIP and ZNT transport genes. Functional characterization of several of the fly genes has revealed functional conservation between related fly and mammalian zinc transporters in some but not all cases, indicating that Drosophila is a useful model for examining mammalian zinc metabolism. Furthermore, Drosophila research, sometimes quite serendipitously, has provided novel insights into the function of zinc transporters and into zinc-related pathologies, which are highlighted here. Finally, the future research potential of the fly in nutrient metabolism is explored, with reference to emerging experimental technologies.

Evidence for a role for the putative Drosophila hGRX1 orthologue in copper homeostasis.

Glutaredoxins are a family of small molecular weight proteins that have a central role in cellular redox regulation. Human GRX1 (hGRX1) has also been shown to play an integral role in copper homeostasis by regulating the redox activity of the metalated sites of copper chaperones such as ATOX1 and SOD1, and the copper efflux proteins ATP7A and ATP7B. To further elucidate the role of hGRX1 in copper homeostasis, we examined the impact of RNA interference-mediated knockdown of CG6852, a putative Drosophila orthologue of hGRX1. CG6852 shares ~41 % amino acid identity with hGRX1 and key functional domains including the metal-binding CXXC motif are conserved between the two proteins. Knockdown of CG6852 in the adult midline caused a thoracic cleft and reduced scutellum, phenotypes that were exacerbated by additional knockdown of copper uptake transporters Ctr1A and Ctr1B. Knockdown of CG6852 in the adult eye enhanced a copper-deficiency phenotype caused by Ctr1A knockdown while ubiquitous knockdown of CG6852 resulted a mild systemic copper deficiency. Therefore we conclude that CG6852 is a putative orthologue of hGRX1 and may play an important role in Drosophila copper homeostasis.

Gas sensing using porous materials for automotive applications.

Improvements in the efficiency of combustion within a vehicle can lead to reductions in the emission of harmful pollutants and increased fuel efficiency. Gas sensors have a role to play in this process, since they can provide real time feedback to vehicular fuel and emissions management systems as well as reducing the discrepancy between emissions observed in factory tests and 'real world' scenarios. In this review we survey the current state-of-the-art in using porous materials for sensing the gases relevant to automotive emissions. Two broad classes of porous material - zeolites and metal-organic frameworks (MOFs) - are introduced, and their potential for gas sensing is discussed. The adsorptive, spectroscopic and electronic techniques for sensing gases using porous materials are summarised. Examples of the use of zeolites and MOFs in the sensing of water vapour, oxygen, NOx, carbon monoxide and carbon dioxide, hydrocarbons and volatile organic compounds, ammonia, hydrogen sulfide, sulfur dioxide and hydrogen are then detailed. Both types of porous material (zeolites and MOFs) reveal great promise for the fabrication of sensors for exhaust gases and vapours due to high selectivity and sensitivity. The size and shape selectivity of the zeolite and MOF materials are controlled by variation of pore dimensions, chemical composition (hydrophilicity/hydrophobicity), crystal size and orientation, thus enabling detection and differentiation between different gases and vapours.

Elemental mapping of the entire intact Drosophila gastrointestinal tract.

The main role of the animal gastrointestinal (GI) tract is the selective absorption of dietary nutrients from ingested food sources. One class of vital micronutrients are the essential biometals such as copper, zinc and iron, which participate in a plethora of biological process, acting as enzymatic or structural co-factors for numerous proteins and also as important cellular signalling molecules. To help elucidate the mechanisms by which biometals are absorbed from the diet, we mapped elemental distribution in entire, intact Drosophila larval GI tracts using synchrotron X-ray fluorescence microscopy. Our results revealed distinct regions of the GI tract enriched for specific metals. Copper was found to be concentrated in the copper cell region but also in the region directly anterior to the copper cells and unexpectedly, in the middle midgut/iron cell region as well. Iron was observed exclusively in the iron cell region, confirming previous work with iron-specific histological stains. Zinc was observed throughout the GI tract with an increased accumulation in the posterior midgut region, while manganese was seen to co-localize with calcium specifically in clusters in the distal Malpighian tubules. This work simultaneously reveals distribution of a number of biologically important elements in entire, intact GI tracts. These distributions revealed not only a previously undescribed Ca/Mn co-localization, but also the unexpected presence of additional Cu accumulations in the iron cell region.

Local and systemic effects of targeted zinc redistribution in Drosophila neuronal and gastrointestinal tissues.

While the effects of systemic zinc ion deficiency and toxicity on animal health are well documented, the impacts of localized, tissue-specific disturbances in zinc homeostasis are less well understood. Previously we have identified zinc dyshomeostasis scenarios caused by the targeted manipulation of zinc transport genes in the Drosophila eye. Over expression of the uptake transporter dZIP42C.1 (dZIP1) combined with knockdown of the efflux transporter dZNT63C (dZNT1) causes a zinc toxicity phenotype, as does over expression of dZIP71B or dZNT86D. However, all three genotypes result in different morphologies, responses to dietary zinc, and genetic interactions with the remaining zinc transport genes, indicating that each causes a different redistribution of zinc within affected cells. dZNT86D (eGFP) over expression generates a completely different phenotype, interpreted as a Golgi zinc deficiency. Here we assess the effect of each of these transgenes when targeted to a range of Drosophila tissues. We find that dZIP71B is a particularly potent zinc uptake gene, causing early developmental lethality when targeted to multiple different tissue types. dZNT86D over expression (Golgi-only zinc toxicity) is less deleterious, but causes highly penetrant adult cuticle, sensory bristle and wing expansion defects. The dZIP42C.1 over expression, dZNT63C knockdown combination causes only moderate adult cuticle defects and sensitivity to dietary zinc when expressed in the midgut. The Golgi-only zinc deficiency caused by dZNT86D (eGFP) expression results in mild cuticle defects, highly penetrant wing expansion defects and developmental lethality when targeted to the central nervous system and, uniquely, the fat bodies.

The Potential of AI and ChatGPT in Improving Agricultural Injury and Illness Surveillance Programming and Dissemination.

Generative Artificial Intelligence (AI) provides unprecedented opportunities to improve injury surveillance systems in many ways, including the curation and publication of information related to agricultural injuries and illnesses. This editorial explores the feasibility and implication of ChatGPT integration in an international sentinel agricultural injury surveillance system, AgInjuryNews, highlighting that AI integration may enhance workflows by reducing human and financial resources and increasing outputs. In the coming years, text intensive natural language reports in AgInjuryNews and similar systems could be a rich source for data for ChatGPT or other more customized and fine-tuned LLMs. By harnessing the capabilities of AI and NLP, teams could potentially streamline the process of data analysis, report generation, and public dissemination, ultimately contributing to improved agricultural injury prevention efforts, well beyond any manually driven efforts.

Medically Attended Suicidality in Youth Who Live on Farms.

Suicides are increasing in U.S. youth, particularly in rural areas. The influence of farming, however, is unclear, as suicide rates are higher in individual adult farm workers, but lower in farming-reliant counties. Early recognition of suicidality (suicidal ideation, intent, or attempt) is a key element of prevention, but there are no prior studies comparing suicidality in farm vs. non-farm youth. The purpose of this study was to examine associations between farm/rural residence and suicidality. Medical records were reused from an existing cohort of child and adolescent patients under surveillance for agricultural injuries in a Wisconsin healthcare system. The sample included 2,010 youth who lived on farms and 51,900 youth who did not live on farms (57% rural). The outcome was medically attended suicidality in 2017-2022 per a composite of diagnoses for suicidal ideation, attempt, or intentional self-harm that presented to ambulatory, emergency, or inpatient care settings. Suicidality was observed in 0.8% of farm, 1.8% of non-farm rural, and 1.6% of non-farm non-rural youth. After covariate adjustment, farm youth had significantly lower odds of suicidality (adjusted odds ratio [aOR] [95% confidence interval; CI] = 0.55 [0.33, 0.91], P = .019), while non-farm rural youth had significantly greater odds of suicidality (aOR [CI] = 1.21 [1.05, 1.40], P = .007), relative to non-farm non-rural youth. Children and adolescents who live on farms are about half as likely to (medically) present for suicidality as compared to their non-farm counterparts, both rural and non-rural. Future research should identify causal suicide protection factors in farm youth.

In vivo zinc toxicity phenotypes provide a sensitized background that suggests zinc transport activities for most of the Drosophila Zip and ZnT genes.

Members of the ZIP (SLC39A) and ZnT (SLC30A) families of transmembrane domain proteins are predicted to transport the essential transition metal zinc across membranes, regulating cellular zinc content and distribution via uptake and efflux at the outer plasma and organellar membranes. Twenty-four ZIP and ZnT proteins are encoded in mammalian genomes, raising questions of whether all actually transport zinc, whether several function together in the same tissues/cell types, and how the activity of these transporters is coordinated. To address these questions, we have taken advantage of the ability to manipulate several genes simultaneously in targeted cell types in Drosophila. Previously we reported zinc toxicity phenotypes caused by combining overexpression of a zinc uptake gene, dZip42C.1, with suppression of a zinc efflux gene, dZnT63C. Here we show that these phenotypes can be used as a sensitized in vivo system to detect subtle alterations in zinc transport activity that would be buffered in healthy cells. Using two adult tissues, the fly eye and midline (thorax/abdomen), we find that when overexpressed, most of the 17 Drosophila Zip and ZnT genes modify the zinc toxicity phenotypes in a manner consistent with their predicted zinc transport activity. In most cases, we can reconcile that activity with the cellular localization of an enhanced green fluorescent protein tagged version of the protein. Additionally, targeted suppression of each gene by RNA interference reveals several of the fly Zip and ZnT genes are required in the eye, indicating that numerous independent zinc transport genes are acting together in a single tissue.

Effect of COMT Val158Met genotype on attention and response to methylphenidate following traumatic brain injury.

PRIMARY OBJECTIVE: To investigate whether COMT Val158Met allele status was associated with (i) attentional performance and (ii) response to methylphenidate (MP) following traumatic brain injury (TBI). METHODS: Forty healthy controls and 32 patients with moderate-severe TBI (Mean time post-injury = 68 days) completed a baseline cognitive assessment. The TBI cohort then participated in a randomized, cross-over, double blind, placebo controlled 2-week MP trial. MP was administered at 0.3 mg/kg twice daily. TBI genotype distribution: val/val n = 11; val/met n = 14; met/met n = 7. RESULTS: There were no significant differences across genotypes on baseline attentional measures. When compared with controls, the val/val group performed significantly more poorly on most measures. The met/met group performed more poorly than controls on measures of speed, but not in strategic control of attention. MP resulted in faster speed of information processing. Repeated measures mixed ANOVAs found only one significant drug × genotype interaction: (F(2,29) = 4.257, p = 0.024) the met/met group demonstrated a greater response to MP on the Symbol Digit Modalities Test. CONCLUSIONS: COMT allele status was not strongly associated with attentional performance or response to MP in the TBI sample. The met/met group, whilst performing slowly, had relatively preserved strategic control of attention.

Copper homeostasis and the ubiquitin proteasome system.

Copper is involved in many physiological pathways and important biological processes as a cofactor of several copper-dependent enzymes. Given the requirement for copper and its potential toxicity, intracellular copper levels are tightly controlled. Disturbances of human copper homeostasis are characterized by disorders of copper overload (Wilson's disease) or copper deficiency (Menkes disease). The maintenance of cellular copper levels involves numerous copper transporters and copper chaperones. Recently, accumulating evidence has revealed that components of the ubiquitin proteasome system (UPS) participate in the posttranslational regulation of these proteins, suggesting that they might play a role in maintaining copper homeostasis. Cellular copper levels could also affect the activity of the UPS, indicating that copper homeostasis and the UPS are interdependent. Copper homeostasis and the UPS are essential to the integrity of normal brain function and while separate links between neurodegenerative diseases and UPS inhibition/copper dyshomeostasis have been extensively reported, there is growing evidence that these two networks might contribute synergistically to the occurrence of neurodegenerative diseases. Here, we review the role of copper and the UPS in the development of Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis, and discuss the genetic interactions between copper transporters/chaperones and components of the UPS.

COMT Val158Met and BDNF Val66Met Single-Nucleotide Polymorphisms Are Not Associated With Emotional Distress One Year After Moderate-Severe Traumatic Brain Injury.

Emotional distress is a common, but poorly addressed, feature of moderate-severe traumatic brain injury (TBI). Previously identified sociodemographic, psychological, and injury-related factors account for only a small proportion of the variability in emotional distress post-TBI. Genetic factors may help to further understand emotional distress in this population. The catechol-O-methyltransferase (COMT) Val158 and brain-derived neurotrophic factor (BDNF) 66Met single-nucleotide polymorphisms (SNPs) have been identified as possible contributory factors to outcomes after TBI. We investigated whether the COMT Val158 and BDNF 66Met SNPs were associated with emotional distress 1 year after moderate-severe TBI, and whether these associations were moderated by age, sex, and TBI severity (as measured by the duration of post-traumatic amnesia [PTA]). Moderate-severe TBI survivors (COMT, n = 391; BDNF, n = 311) provided saliva samples after admission to a TBI rehabilitation hospital. At a follow-up interview ∼1 year after injury, participants completed a self-report measure of emotional distress (Hospital Anxiety and Depression Scale; HADS). Multiple linear regression models were constructed for each SNP to predict total scores on the HADS. Neither COMT Val158 nor BDNF 66Met carriage status (carrier vs. non-carrier) significantly predicted emotional distress (COMT, p = 0.49; BDNF, p = 0.66). Interactions of SNP × age (COMT, p = 0.90; BDNF, p = 0.93), SNP × sex (COMT, p = 0.09; BDNF, p = 0.60), SNP × injury severity (COMT, p = 0.53; BDNF, p = 0.87), and SNP × sex × age (COMT, p = 0.08; BDNF, p = 0.76) were also non-significant. Our null findings suggest that COMT Val158 and BDNF 66Met SNPs do not aid the prediction of emotional distress 1 year after moderate-severe TBI, neither in isolation nor in interaction with age, sex and injury severity. The reporting of null findings such as ours is important to avoid publication bias and prompt researchers to consider the challenges of single-gene candidate studies in understanding post-TBI outcomes. Analyses in larger samples that incorporate multiple genetic factors and their relevant moderating factors may provide a greater understanding of the role of genetics in post-TBI emotional distress.

Interaction between APOE ɛ4 and Age Is Associated with Emotional Distress One Year after Moderate-Severe Traumatic Brain Injury.

Emotional distress is common following moderate-severe traumatic brain injury (TBI) and is associated with poorer post-injury outcomes. Previously investigated sociodemographic, psychological, and injury-related factors account for only a small proportion of variance in post-TBI emotional distress, highlighting a need to consider other factors such as genetic factors. The apolipoprotein E gene (APOE) has been commonly studied in the TBI literature, with the ɛ4 allele linked to worse neuronal repair and recovery. Few studies have investigated the potential relationship between APOE ɛ4 and emotional distress after moderate-severe TBI, and results have been varied. We examined whether APOE ɛ4 was associated with emotional distress 1 year following moderate-severe TBI, and whether this relationship was moderated by age, sex, and TBI severity (as indexed by the duration of post-traumatic amnesia [PTA]). Moderate-severe TBI survivors provided saliva samples following inpatient admission to a TBI rehabilitation hospital. They completed a self-report measure of emotional distress, the Hospital Anxiety and Depression Scale (HADS), at a follow-up interview ∼1 year post-injury. Complete genetic and follow-up data were available for 441 moderate-severe TBI survivors (mean age = 39.42 years; 75% male). We constructed a linear regression model that included APOE ɛ4 carriage status (carrier vs. non-carrier) and interactions with age, sex, and TBI severity (APOE × age, APOE × sex, APOE × age × sex, and APOE × PTA duration) to predict total score on the HADS, while covarying for the main effects of age, sex, PTA duration, and previous head injury. There was a significant main effect of APOE ɛ4, whereby ɛ4 carriers reported less emotional distress than non-carriers (p = 0.04). However, we also found a significant interaction with age such that APOE ɛ4 carriers reported increasingly greater emotional distress with older age compared with non-carriers (p = 0.01). A sensitivity analysis (n = 306) suggested that the APOE × age interaction, and main effects of age and previous head injury, were not unique to individuals with pre-injury mental health problems (n = 136). However, the main effect of APOE ɛ4 was no longer significant when individuals with pre-injury mental health problems were removed. Our findings highlight the importance of considering moderation of genetic associations, suggesting that APOE ɛ4 may be a risk factor for emotional distress specifically among older survivors of moderate-severe TBI. If these findings can be independently replicated, APOE ɛ4 carriage status, interpreted in the context of age, could be incorporated into risk prediction models of emotional distress after moderate-severe TBI, enhancing targeted early detection and intervention efforts.

Systematic functional characterization of putative zinc transport genes and identification of zinc toxicosis phenotypes in Drosophila melanogaster.

The heavy metal zinc is an essential component of the human diet and is incorporated as a structural component in up to 10% of all mammalian proteins. The physiological importance of zinc homeostasis at the cellular level and the molecular mechanisms involved in this process have become topics of increasing interest in recent years. We have performed a systematic functional characterization of the majority of the predicted Drosophila Zip (zinc/iron regulated transporter-related protein) and ZnT genes, using the Gal4-UAS system to carry out both ubiquitous and targeted over-expression and suppression studies for 13 of the 17 putative zinc transport genes identified to date. We found that six of these 13 genes may be essential for fly viability and that three of the remaining seven demonstrate over-expression phenotypes. Our findings reaffirm the previously proposed function of dZnT63C (CG17723: FBgn005432) as an important zinc efflux protein and indicate that the fly homolog of hZip1, dZip42C.1 (CG9428: FBgn0033096), is a strong zinc importer in Drosophila. By combining over-expression of dZip42C.1 with suppression of dZnT63C we were able to produce easily identifiable zinc toxicosis phenotypes, which can be rescued or worsened by modifying dietary zinc content. Our findings show that a genetically based zinc toxicosis situation can be therapeutically treated or exacerbated by modifications to the diet, providing a sensitized background for future, more detailed studies of Zip/ZnT function.

Molecular physiology of copper in Drosophila melanogaster.

In this review, I look at advances made in our understanding of the molecular physiology of copper homeostasis in the vinegar fly Drosophila melanogaster over the past five years, focussing in particular on the most recent 24 months. Firstly, I review publications investigating the physiological and genetic basis of dietary copper toxicity and tolerance, with particular attention paid to the identification of novel transcriptional and post translational regulators of copper homeostasis. Then I hone in on the growing body of evidence linking copper dysregulation with aberrant neuronal development and function.