Property Buyouts After Natural Disasters: The Economic Implications for Texas Residents

The State of Texas is prone to a myriad of natural disasters—hurricanes, tornados, floods, wildfires—that adversely affect its residents and have significant financial impacts ranging from minor repairs to complete loss of property. When the damage is severe, the most practical solution can be a public buyout of private property. This brief highlights economic and public policy implications of Texas municipalities purchasing property from residents living in areas repeatedly damaged by natural disasters. The author is a Bush School student whose work was supported by a research fellowship from The Texas Lyceum.The Texas Lyceu

Property Buyouts After Natural Disasters: The Economic Implications for Texas Residents

The State of Texas is prone to a myriad of natural disasters—hurricanes, tornados, floods, wildfires—that adversely affect its residents and have significant financial impacts ranging from minor repairs to complete loss of property. When the damage is severe, the most practical solution can be a public buyout of private property. This brief highlights economic and public policy implications of Texas municipalities purchasing property from residents living in areas repeatedly damaged by natural disasters. The author is a Bush School student whose work was supported by a research fellowship from The Texas Lyceum.The Texas Lyceu

Hydrogen peroxide treatment in Atlantic salmon induces stress and detoxification response in a daily manner

Daily variation in the absorption, metabolism and excretion of toxic substances will ultimately determine the actual concentration to which the cells and tissues are exposed. In aquaculture, Atlantic salmon (Salmo salar) can be frequently exposed to hydrogen peroxide (H2O2) to treat topical skin and gill infections, particularly in relation to parasitic infections (e.g. sea liceLepeophtheirus salmonisand amoebic gill disease caused byNeoparamoeba perurans). It is well accepted that the time of administration influences pharmacodynamics and pharmacokinetics of drugs which in turn affects their efficacy and toxicity. Consequently, a better understanding of drug side effects as a function of time of day exposure would help to improve treatment efficacy and fish welfare. To this end, salmon were exposed to H2O2(1500 mg/L) for 20 min at six different times of the day during a 24-h cycle and we investigated the time-dependent effects of exposure on physiological stress (glucose, lactate and cortisol) and antioxidant enzyme expression (gpx1, cat, Mn-sodandhsp70) in liver and gills. In addition, at each sampling point, 8 control fish were also sampled. Our results revealed that the time of administration of H2O2caused significant differences in the induction of both physiological and oxidative stress responses. Glucose and lactate were higher in the treated fish during daytime whereas cortisol levels appeared to be systematically increased (>1000 ng/mL) after H2O2treatment irrespective of exposure time, although differences with control levels were higher during the day. In liver, gene expression of antioxidant enzymes displayed daily rhythmicity in both treated and control groups and showed higher mRNA expression levels in salmon treated with H2O2at ZT6 (6 h after lights onset). In gills, rhythmic expression was only found forgpx1in the control fish and forhsp70andMn-sodin the treated groups. However, in the treated salmon, higher gene expression levels of all the investigated enzymes were also observed at ZT6-10. Clock gene expression showed rhythmicity only in the liver in accordance with the daily rhythm of enzyme expression observed in this tissue. Altogether, this study provides first evidence of chronotoxicity in Atlantic salmon treated with H2O2and suggests increased sublethal toxic effect during the first half of the day. These results have direct relevance to the salmon and broader aquaculture industry by optimising the timing of treatment administration, opening the door to chronotherapy to treat fish diseases

Development of a water-stable agar-based diet for the supplementary feeding of cleaner fish ballan wrasse (Labrus bergylta) deployed within commercial Atlantic salmon (Salmon salar) net-pens

The aim of this project was to develop a water-stable and palatable diet for the supplementary feeding of wrasse deployed in salmon sea-pens using a gelling agent mixed with a manufactured dry-feed component. Three binders (gelatine from cold water fish skin, beef gelatin and agar-agar) were compared for water-gel strength over a range of concentrations. Gel formed using agar was found to be significantly stronger than the other binders tested. An experimental aqua-feed made using a grinded, dry ingredient mix binded with 20g/L agar solution at 1/1.6 (w/v) ratio and offered as blocks within individual feeders was water-stable for 7 days when deployed fresh or following a week of preservation at -20°C. Farmed ballan wrasse in tanks fed on the agar-based diet within 2 days of deployment. Wild wrasse stocked in salmon sea-pens at low density (1.2-2.1%), up to 4 weeks prior the start of the trial and not previously fed a manufactured diet first ingested the agar feed within 2 weeks and total feed intake significantly increased afterwards. Feed intake was significantly higher from feeders placed within a small feeding shelter made of artificial kelp than within the large wrasse shelter. No nutrient leaching after water immersion and no alterations in the fatty acid profile after preparation of the experimental feed was found. A manufactured grinded ingredient mix binded with 20g/L agar solution at a 1/1.6 (w/v) ratio and offered within static feeders is proposed as the basis of a novel supplementary feeding methodology for cleaner fish wrasse deployed in salmon sea-pens. This methodology has the potential to facilitate wrasse feeding and to allow the monitoring of feed intake to safeguard the health, welfare and delousing activity of the biological stock over the salmon rearing cycle

Temperature-induced testicular germ cell loss and recovery in Nile tilapia Oreochromis niloticus

Water temperature is a critical external factor influencing gonadal development in fish. This research aimed to study the impact of elevated temperature on testicular germ cell survival and reproductive capacity of Nile tilapia. Male Nile tilapia were exposed to high temperatures of either 36 (HT1) or 37°C (HT2) for 3000 degree-days (DD) and thereafter returned to the control temperature of 27°C (CT) for 2200 DD. The deleterious effects on testicular germ and somatic cells were observed histologically, characterised by vacuolisation, atrophy and the loss of spermatogenic cells in testes with a more severe impact of HT2 compared to HT1. Interestingly, serum 11-ketotestosterone (11-KT) and testosterone (T) levels tended to be higher during the heat treatments than CT. Expression levels of germline-specific genes piwil1, piwil2 and nanos2 and Bcl-2 family genes, bcl-xLb and baxa were significantly reduced during the heat treatment compared to CT, more so in the HT2, while the levels of nanos3 and gfra1 transcripts were only significantly reduced in HT2, implying a significant loss of spermatogonial stem cell (SSC) and spermatogonia in HT2. The effect of HT2 is further evidenced by the significantly reduced sperm density and fertilisation rate compared to CT and HT1 at the end of the recovery period but complete sterility was not induced by HT2. Overall, the present study showed significant effects of HT2 on germ cell survival with histological changes in testes, reduced milt quality, increased 11-KT, and decreased expression of germline-specific genes, SSC marker genes and Bcl-2 family genes in testes which could therefore be potential target genes for sterilisation by genome editing

Expression pattern of nanos, piwil, dnd, vasa and pum genes during ontogenic development in Nile tilapia Oreochromis niloticus

Primordial germ cells (PGCs) are specified by maternally provided determinants in fish. PGCs migrate then into prospective gonadal sites during early development and give rise to germ cell lineage. PGC disrupted animals do not sexually mature which has a range of commercial as well as environmental benefits. To find potential target genes for sterilisation of Nile tilapia, relative mRNA abundance patterns and tissue distribution of four nanos, two piwil, dnd1, vasa and three pum genes were investigated during ontogenic development from unfertilised eggs to newly hatched larvae and in adult tissues, respectively. The ontogenic pattern of RNA abundance revealed that all the investigated gene transcripts are maternally deposited to varying degrees, except for nanos2 which is not expressed in eggs. The ontogenic patterns of relative RNA abundance could be grouped into three categories. The first one, including nanos3, piwil1, piwil2, dnd1 and vasa, showed abundant transcript levels during early developmental stages which are then degraded during the period of maternal to zygotic transition between blastula and gastrula stages with a reduction in expression of four to five orders of magnitude by hatching stage. Another, including pum2 and pum3, showed similar patterns to the first group, but the transcript levels are reduced by only two orders of magnitude. The third group, including nanos1a, nanos1b and pum1, was characterised by a zygotic increase. nanos2 had no detectable transcripts until hatching stage. The tissue screening of nanos1a, nanos1b, pum1, pum2 and pum3 showed that they are expressed in various tissues, implying their potential pleiotropic effects in these tissues apart from gonads. In contrast, nanos3, piwil1, piwil2, dnd1 and vasa appeared to be exclusively expressed in gonads (both ovary and testis), and nanos2 showed testis-specific expression. Based on these results nanos3, piwil1, piwil2, dnd1 and vasa were prioritised among the 11 selected genes as potential target genes for sterilisation in Nile tilapia as they have no significant zygotic expression during embryogenesis, they are expressed exclusively in gonads and maternally deposited. These features suggest a potential role of these genes in the specification and maintenance of PGCs during the ontogenic development of Nile tilapia

Opening wedge high tibial osteotomy performed without filling the defect but with locking plate fixation (TomoFix™) and early weight-bearing: Prospective evaluation of bone union, precision and maintenance of correction in 51 cases

SummaryIntroductionA medial opening wedge high tibial osteotomy (HTO), where the osteotomy site is filled, is often preferred to a lateral closing osteotomy, but filling the defect can lead to certain complications.HypothesisA medial opening HTO can be performed without filling the bone defect if fixation is carried out with a specially-designed stiff locking plate.Patients and methodsFifty-one patients, 37 to 72 years of age where followed prospectively and continuously from 2003 to 2006. A single surgical technique was used: medial opening HTO with locked plate fixation (TomoFix™, Synthes) but without filling the defect. The preoperative genu varum could not exceed 15°. The following were evaluated: time to return to weight-bearing, IKS functional score, long-leg standing film performed preoperative, postoperative and at follow-up to evaluate limb alignment and validate the precision of the correction and its stability over time. A measurement of the area of bone union in the osteotomy site was used to quantify the rate of union.ResultsBone union occurred at 4.5 months on average; two cases of incomplete union (7%) were found and revised with an autograft at 7 and 9 months. Lower-limb alignment was 7.5° of varus on average before surgery (3° to 15° varus, SD=2.85) and 1.2° of valgus on average after the surgery (4° varus to 5° valgus, SD=1.78). The correction was maintained at 1 year post-surgery. The average IKS knee score went from 69±15.5 (range 25 to 96) before surgery to 90±7.4 (range 66 to 98) at follow-up (P=0.0001). Full weight-bearing without assistance was possible after 3 months on average (range 1.5 to 8, SD=1.21). Forty-seven patients (92%) were fully weight-bearing after 2 months. Forty-eight patients were able to return to work and sporting activities at the same or a higher level than before the procedure.DiscussionBone union seems to happen more slowly when the defect is filled; however, there are doubts about radiological evaluation of bone union in different published studies. When osteotomy defect was left unfilled in this study, union and filling of 4/5 of the osteotomy site was obtained in 4.2 months for 49 of the 51 cases. Fixation with the locking plate is reliable and provides stable correction and the option for early weight-bearing.Level of proofLevel IV, prospective cohort study

The potential of alternative lighting-systems to suppress pre-harvest sexual maturation of 1+ Atlantic salmon (Salmo salar) post-smolts reared in commercial sea-cages

The aim of this study was to compare the efficiency of new candidate lighting-technologies (50W ‘blue’ light-emitting-diode (B, λmax = 465 nm); 232 W ‘green’ hot cathode, (G, λmax = 546 nm); 400 W ‘red’ tungsten-halogen, (R, λmax = 667 to 740 nm)) against a standard 400 W ‘white’ metal-halide used as control technology (C, broad spectrum) at suppressing sexual maturation of 1+ Atlantic salmon (Salmo salar) in sea-cages. A total of seven experimental set-ups were tested on a commercial-scale in three trials using a standardised photoperiod regime in the form of continuous artificial-light (LL) applied from winter to summer solstice during the second year at sea. The experimental stocks were raised under an ambient thermal regime that was similar across all trials. Technical performances (spectral output, light-attenuation and irradiance distance) of the individual light-units were measured and light-perception was assessed by quantifying plasma melatonin levels. Body-size parameters (BW, FL, K) were measured at the switch-on and turn-off of the photoperiod regimes. Maturation rates were estimated at the end of the light-treatments and at harvest. The B-unit provided the shortest effective irradiance distance (distance from the light-bulb to the minimum irradiance suppressing plasma melatonin to basal day-time level = 0.016 W m-2) but the longest relative to its energy consumption; while the G- and R-units did not offer a comparative advantage over the C-unit in that regard (B>C>G>R). Nocturnal plasma-melatonin and maturation rate decreased proportionally to the light-intensity provided using a range of technologies emitting distinct spectral profiles. Light-intensity rather than light-spectral composition appeared to be the prime parameter negatively affecting sexual maturation. Maximal suppression of maturation was observed in treatments depressing nocturnal plasma melatonin to a 1.2-fold but not to a 1.7-fold increase compared to daytime levels, confirming that a threshold level of light-irradiance is necessary to obtain the desired effect. Results suggest that this can be achieved under standard commercial practices by applying, over the photoperiod regime presently used, continuous artificial-illumination with an (electrical) energy consumption of 0.28 Wh m-3 generating a mean-irradiance of 0.012 W m-2 and providing a minimum volume of effective irradiance equivalent to 12% of the rearing-environment. Such a low volume of biologically effective irradiance was likely sufficient due to the strong photic attraction already reported in Atlantic salmon. Maximal suppression of pre-harvest sexual maturation can be achieved in the Atlantic salmon on-growing industry using alternative light-technologies. Present data provides methods and threshold values favouring the implementation of photoperiod-manipulation to suppress pre-harvest maturation at the most advantageous scale and cost

Effects of GnRHa slow-release implants in the steroid profile of isolated couples of Arapaima gigas (Schinz, 1822).

The aim of the study were 1) to induce spawning of isolated broodstock pairs with GnRHa slow-release implant technique (Zohar and Mylonas, 2001) and monitor steroid levels in blood plasma; and 2) characterise cephalic secretions through proteomic and steroid analyses during reproduction and parental care post spawnin

Physiological impact and comparison of mutant screening methods in piwil2 KO founder Nile tilapia produced by CRISPR/Cas9 system

The application of genome engineering techniques to understand the mechanisms that regulate germ cell development opens promising new avenues to develop methods to control sexual maturation and mitigate associated detrimental effects in fish. In this study, the functional role of piwil2 in primordial germ cells (PGCs) was investigated in Nile tilapia using CRISPR/Cas9 and the resultant genotypes were further explored. piwil2 is a gonad-specific and maternally deposited gene in Nile tilapia eggs which is known to play a role in repression of transposon elements and is therefore thought to be important for maintaining germline cell fate. A functional domain of piwil2, PIWI domain, was targeted by injecting Cas9 mRNA and sgRNAs into Nile tilapia embryos at 1 cell stage. Results showed 54% of injected mutant larvae had no or less putative PGCs compared to control fish, suggesting an essential role of piwil2 in survival of PGCs. The genotypic features of the different phenotypic groups were explored by next generation sequencing (NGS) and other mutant screening methods including T7 endonuclease 1 (T7E1), CRISPR/Cas-derived RNA-guided engineered nuclease (RGEN), high resolution melt curve analysis (HRMA) and fragment analysis. Linking phenotypes to genotypes in F0 was hindered by the complex mosacism and wide indel spectrum revealed by NGS and fragment analysis. This study strongly suggests the functional importance of piwil2 in PGCs survival. Further studies should focus on reducing mosaicism when using CRISPR/Cas9 system to facilitate direct functional analysis in F0