Dry Down Tolerance of the Florida Apple Snail (Pomacea paludosa, Say): Effects of Age and Season

This Research Work Order includes three experiments to look at apple snail dry down survival as a function of age and season. Two of those experiments have been completed and the third one will likely run through February (depending on snail survival). The third experiment began on September 2 1, 1998. The detailed results of Experiment # 1 and #2 were reported in the update report of 10/15/98. The overall survival for Experiments #I and #2 are included herein for comparison with Experiment #3. (7 page document

Assessing the impact of the Lake Kissimmee restoration on apple snails

Seasonal fluctuations in rainfall occur naturally in Florida, historically producing correspondingly large intra-annual and inter-annual fluctuations in lake water levels. As a result, "normal" lake levels are elusive; the norm is for wide fluctuations, a pattern which earned them the descriptive title, "astatic", or unstable (Brenner et. al. 1990). Lake Kissimmee, in Osceola County, FL, had a mean average water level fluctuation of 1.4 meters, but over several years varied as much as 3.7 meters (Grocki 1975).The substrate and vegetative communities, in part, reflect the pattern of hydrologic fluctuations, their timing, duration, and frequency. Topographic variability in lake systems, coupled with their hydrologic patterns, yield a mosaic of shrubby, emergent and submerged plant habitats in the littoral zone of the lake. Fish and wildlife have adapted accordingly, and successfully forage and reproduce in these highly fluctuating systems. Installation and operation of water control structures over the past 40 to 50 years have dampened the degree of hydrologic fluctuations in many Florida lakes, resulting in long term stabilization oflake levels [Holcomb and Wegener 1971, Wegener et. al. 1974, Fox et. al. 1977, Moyer and Williams 1982, Florida Game and Fresh Water Fish Commission (GFC) 1995]. The mean annual flux on Lake Kissimmee was reduced from 1.4 meters to 0.9 meters (Wegener et al 1973). In addition, increased nutrient inputs to Florida's watersheds from agricultural and urban development have resulted in lake eutrophication (Wegener et. al. 1974, Moyer and Williams 1982). As nutrients increased and water levels stabilized, rooted aquatic macrophytes expanded and organic debris accumulated to form undesirable lake substrates. Fish populations suffer from drops in accumulated to form undesirable lake substrates. Fish populations suffer from drops in dissolved oxygen associated with decaying algae and plant matter, the alteration of plant community composition, and poor habitat quality of the substrate (Wegener and Williams 1974). To remedy these problems in Florida lakes, the Florida Game and Fresh Water Fish Commission initiated a lake restoration program in 1971 which emphasizes the use of a lake draw down to expose sediments (GFC 95). The objective ofthe program is to reduce undesirable plant species, expand desirable plant communities, and consolidate flocculent organic sediments (Holcomb and Wegener 1971, Wegener et. al. 1974, Fox et. al. 1977, Cooke 1980, Tarver 1980, GFC 1995). In addition, muck removal operations following lake level draw downs are meant to resolve the problem of extensive build up of organic sediments (GFC 1995, Moyer et. al. 1995). The goal of the draw down and restoration activity is to improve aquatic habitat in support of fisheries and wildlife while improving lake quality for recreational usage (e.g. sport fishing) (Wegener and Williams 1974, Tarver 1980,. GFC 1995). The Florida Game and Fresh Water Fish Commission (GFC), in cooperation with the South Florida Water Management District (SFWMD), conducted a draw down of Lake Kissimmee from December 1995- June 1996, dropping lake levels by approximately 1.7 meters. The Lake Kissimmee draw down provided an excellent opportunity to investigate the impact of management techniques on an invertebrate which is a critical component of the central lakes food web, the Florida apple snail (Pomacea paludosa, SAY). Although data on the responses of some invertebrate species 2 to draw downs in central Florida are available (Wegener et. al. 1974, Fox et. al. 1977, Butler et. al. 1992), no published studies document the responses of P. paludosa. The Florida apple snail belongs to the tropical family of aquatic snails, Pilidae, which inhabitant wetland areas in Florida, Central and South America, Africa and India. Most Pilidae habitat typically (under natural hydrologic patterns) experiences a seasonal dry down, and the Florida apple snail is no exception. Pilidae snails utilize both a lung and gill for respiration (Andrews 1965). The dual respiratory system enables these animals to tolerate daily and seasonal dissolved oxygen fluctuations, permits egg-laying above water level (eggs thus avoid hypoxia and predation), and, in some Pilid species, enables adults to maintain aerobic respiration during the dry-season (McClary 1964, Burky et al. 1972, Aldridge 1983). Apple snails are critical components of lake food webs in Florida. They are prey to alligators (Alligator mississippiensis)( Delany and Abercrombie 1986), fish (Lepomis microlophus)(Chable 1947), turtles (Trionyxferox) (Dalrymple 1977), and ibis (Eudocimus albus)(Kushlan 1974). Apple snails comprise over 75% ofthe diet of the limpkins (Aramus guaraunaXCottam 1942), and nearly 100% ofthe diet of endangered snail kite (Rostramus sociabilis)(Snyder and Snyder 1969). Although the majority of the snail kite population occupies wetland habitats in south Florida throughout the year, they have been found to emigrate from this area when the dry season escalates into a prolonged drought (Beissinger and Takekawa 1983, Bennetts and Kitchens 1997). Researchers have identified the central lakes system as a critical refuge for the snail kite during these droughts (Beissinger and Takekawa 1983, Bennetts and Kitchens 1997). In 3 addition, the kites have been consistently nesting (even in non-drought years) on Lake Kissimmee and Lake Tohopekaliga since the early 1980's, providing further support (in the form of suitable foraging and nesting habitat) for the endangered kite population (Beissinger and Takekawa 1983, Bennetts and Kitchens 1997). The impetus for the Lake Kissimmee draw down is habitat improvement for fisheries and wildlife (GFC 1995). A conservation priority ranking system for Florida wildlife identifies the snail kite and limpkin, largely due to their specialized diet of apple snails, as deserving special attention for monitoring and management (Milsap et. a1. 1990).Moyer et a1. 1991 specifically recommended an evaluation ofthe impact of lake draw downs on apple snails. In this report we present the findings of a three-year study ofthe immediate and long term impacts ofthe Lake Kissimmee draw down and restoration activity on apple snail populations. The objectives ofthis research are as follows: • To study the impacts oflake restoration activity (e.g. draw down, muck removal) on snail populations in several sites throughout the lake by assessing pre-draw down and post-draw down snail abundance~ • To study the movement patterns of snails to find out what proportion ofthe population migrates to deeper water or become stranded in the dry down area as lake levels recede; • To study the capacity for snails to survive in dry down conditions (Document has 55 pages

Cancer risk in 680 000 people exposed to computed tomography scans in childhood or adolescence: Data linkage study of 11 million Australians

Objective To assess the cancer risk in children and adolescents following exposure to low dose ionising radiation from diagnostic computed tomography (CT) scans. Design Population based, cohort, data linkage study in Australia. Cohort members 10.9 million people identified from Australian Medicare records, aged 0-19 years on 1 January 1985 or born between 1 January 1985 and 31 December 2005; all exposures to CT scans funded by Medicare during 1985-2005 were identified for this cohort. Cancers diagnosed in cohort members up to 31 December 2007 were obtained through linkage to national cancer records. Main outcome Cancer incidence rates in individuals exposed to a CT scan more than one year before any cancer diagnosis, compared with cancer incidence rates in unexposed individuals. Results 60 674 cancers were recorded, including 3150 in 680 211 people exposed to a CT scan at least one year before any cancer diagnosis. The mean duration of follow-up after exposure was 9.5 years. Overall cancer incidence was 24% greater for exposed than for unexposed people, after accounting for age, sex, and year of birth (incidence rate ratio (IRR) 1.24 (95% confidence interval 1.20 to 1.29); P<0.001). We saw a dose-response relation, and the IRR increased by 0.16 (0.13 to 0.19) for each additional CT scan. The IRR was greater after exposure at younger ages (P<0.001 for trend). At 1-4, 5-9, 10-14, and 15 or more years since first exposure, IRRs were 1.35 (1.25 to 1.45), 1.25 (1.17 to 1.34), 1.14 (1.06 to 1.22), and 1.24 (1.14 to 1.34), respectively. The IRR increased significantly for many types of solid cancer (digestive organs, melanoma, soft tissue, female genital, urinary tract, brain, and thyroid); leukaemia, myelodysplasia, and some other lymphoid cancers. There was an excess of 608 cancers in people exposed to CT scans (147 brain, 356 other solid, 48 leukaemia or myelodysplasia, and 57 other lymphoid). The absolute excess incidence rate for all cancers combined was 9.38 per 100 000 person years at risk, as of 31 December 2007. The average effective radiation dose per scan was estimated as 4.5 mSv. Conclusions The increased incidence of cancer after CT scan exposure in this cohort was mostly due to irradiation. Because the cancer excess was still continuing at the end of follow-up, the eventual lifetime risk from CT scans cannot yet be determined. Radiation doses from contemporary CT scans are likely to be lower than those in 1985-2005, but some increase in cancer risk is still likely from current scans. Future CT scans should be limited to situations where there is a definite clinical indication, with every scan optimised to provide a diagnostic CT image at the lowest possible radiation dose

Natural and Vaccine-Mediated Immunity to Salmonella Typhimurium is Impaired by the Helminth Nippostrongylus brasiliensis

The impact of exposure to multiple pathogens concurrently or consecutively on immune function is unclear. Here, immune responses induced by combinations of the bacterium Salmonella Typhimurium (STm) and the helminth Nippostrongylus brasiliensis (Nb), which causes a murine hookworm infection and an experimental porin protein vaccine against STm, were examined. Mice infected with both STm and Nb induced similar numbers of Th1 and Th2 lymphocytes compared with singly infected mice, as determined by flow cytometry, although lower levels of secreted Th2, but not Th1 cytokines were detected by ELISA after re-stimulation of splenocytes. Furthermore, the density of FoxP3+ T cells in the T zone of co-infected mice was lower compared to mice that only received Nb, but was greater than those that received STm. This reflected the intermediate levels of IL-10 detected from splenocytes. Co-infection compromised clearance of both pathogens, with worms still detectable in mice weeks after they were cleared in the control group. Despite altered control of bacterial and helminth colonization in co-infected mice, robust extrafollicular Th1 and Th2-reflecting immunoglobulin-switching profiles were detected, with IgG2a, IgG1 and IgE plasma cells all detected in parallel. Whilst extrafollicular antibody responses were maintained in the first weeks after co-infection, the GC response was less than that in mice infected with Nb only. Nb infection resulted in some abrogation of the longer-term development of anti-STm IgG responses. This suggested that prior Nb infection may modulate the induction of protective antibody responses to vaccination. To assess this we immunized mice with porins, which confer protection in an antibody-dependent manner, before challenging with STm. Mice that had resolved a Nb infection prior to immunization induced less anti-porin IgG and had compromised protection against infection. These findings demonstrate that co-infection can radically alter the development of protective immunity during natural infection and in response to immunization

Genetic modifiers of radon-induced lung cancer risk: a genome-wide interaction study in former uranium miners

PURPOSE: Radon is a risk factor for lung cancer and uranium miners are more exposed than the general population. A genome-wide interaction analysis was carried out to identify genomic loci, genes or gene sets that modify the susceptibility to lung cancer given occupational exposure to the radioactive gas radon. METHODS: Samples from 28 studies provided by the International Lung Cancer Consortium were pooled with samples of former uranium miners collected by the German Federal Office of Radiation Protection. In total, 15,077 cases and 13,522 controls, all of European ancestries, comprising 463 uranium miners were compared. The DNA of all participants was genotyped with the OncoArray. We fitted single-marker and in multi-marker models and performed an exploratory gene-set analysis to detect cumulative enrichment of significance in sets of genes. RESULTS: We discovered a genome-wide significant interaction of the marker rs12440014 within the gene CHRNB4 (OR = 0.26, 95% CI 0.11-0.60, p = 0.0386 corrected for multiple testing). At least suggestive significant interaction of linkage disequilibrium blocks was observed at the chromosomal regions 18q21.23 (p = 1.2 × 10-6), 5q23.2 (p = 2.5 × 10-6), 1q21.3 (p = 3.2 × 10-6), 10p13 (p = 1.3 × 10-5) and 12p12.1 (p = 7.1 × 10-5). Genes belonging to the Gene Ontology term "DNA dealkylation involved in DNA repair" (GO:0006307; p = 0.0139) or the gene family HGNC:476 "microRNAs" (p = 0.0159) were enriched with LD-blockwise significance. CONCLUSION: The well-established association of the genomic region 15q25 to lung cancer might be influenced by exposure to radon among uranium miners. Furthermore, lung cancer susceptibility is related to the functional capability of DNA damage signaling via ubiquitination processes and repair of radiation-induced double-strand breaks by the single-strand annealing mechanism

The P323L substitution in the SARS-CoV-2 polymerase (NSP12) confers a selective advantage during infection

Background The mutational landscape of SARS-CoV-2 varies at the dominant viral genome sequence and minor genomic variant population. During the COVID-19 pandemic, an early substitution in the genome was the D614G change in the spike protein, associated with an increase in transmissibility. Genomes with D614G are accompanied by a P323L substitution in the viral polymerase (NSP12). However, P323L is not thought to be under strong selective pressure. Results Investigation of P323L/D614G substitutions in the population shows rapid emergence during the containment phase and early surge phase during the first wave. These substitutions emerge from minor genomic variants which become dominant viral genome sequence. This is investigated in vivo and in vitro using SARS-CoV-2 with P323 and D614 in the dominant genome sequence and L323 and G614 in the minor variant population. During infection, there is rapid selection of L323 into the dominant viral genome sequence but not G614. Reverse genetics is used to create two viruses (either P323 or L323) with the same genetic background. L323 shows greater abundance of viral RNA and proteins and a smaller plaque morphology than P323. Conclusions These data suggest that P323L is an important contribution in the emergence of variants with transmission advantages. Sequence analysis of viral populations suggests it may be possible to predict the emergence of a new variant based on tracking the frequency of minor variant genomes. The ability to predict an emerging variant of SARS-CoV-2 in the global landscape may aid in the evaluation of medical countermeasures and non-pharmaceutical interventions

Para-infectious brain injury in COVID-19 persists at follow-up despite attenuated cytokine and autoantibody responses

To understand neurological complications of COVID-19 better both acutely and for recovery, we measured markers of brain injury, inflammatory mediators, and autoantibodies in 203 hospitalised participants; 111 with acute sera (1–11 days post-admission) and 92 convalescent sera (56 with COVID-19-associated neurological diagnoses). Here we show that compared to 60 uninfected controls, tTau, GFAP, NfL, and UCH-L1 are increased with COVID-19 infection at acute timepoints and NfL and GFAP are significantly higher in participants with neurological complications. Inflammatory mediators (IL-6, IL-12p40, HGF, M-CSF, CCL2, and IL-1RA) are associated with both altered consciousness and markers of brain injury. Autoantibodies are more common in COVID-19 than controls and some (including against MYL7, UCH-L1, and GRIN3B) are more frequent with altered consciousness. Additionally, convalescent participants with neurological complications show elevated GFAP and NfL, unrelated to attenuated systemic inflammatory mediators and to autoantibody responses. Overall, neurological complications of COVID-19 are associated with evidence of neuroglial injury in both acute and late disease and these correlate with dysregulated innate and adaptive immune responses acutely