Effects of wild and farm-grown macroalgae on the growth of juvenile South African abalone Haliotis midae Linnaeus

The effect of various macroalgal diets on the growth of grow-out (> 20 mm shell length) South African abalone Haliotis midae was investigated on a commercial abalone farm. The experiment consisted of four treatments: fresh kelp blades (Ecklonia maxima [Osbeck] Papenfuss) (~ 10 % protein); farmed, protein-enriched Ulva lactuca Linnaeus (~26 % protein) grown in aquaculture effluent; wild U. lactuca (~ 20 % protein); and a combination (mixed) diet of kelp blades + farmed U. lactuca. Abalone grew best on the combination diet (0.423 ± 0.02% weight dayˉ¹ SGR [specific growth rate]; 59.593 ± 0.02 µm dayˉ¹ DISL [daily increment in shell length]; 1.093 final CF [condition factor]) followed by the kelp only diet (0.367 ± 0.02 % weight dayˉ¹ SGR; 53.148 ± 0.02 µm dayˉ¹ DISL; 1.047 final CF), then the farmed, protein-enriched U. lactuca only diet (0.290 ± 0.02% weight dayˉ¹ SGR; 42.988 ± 0.03 µm dayˉ¹ DISL; 1.013 final CF) that in turn outperformed the wild U. lactuca only diet (-0.079 ± 0.01 % weight dayˉ¹ SGR; 3.745 ± 0.02 µm dayˉ¹ DISL; 0.812 final CF). The results suggest that protein alone could not have accounted for the differences produced by the varieties of U. lactuca and that the gross energy content is probably important.Web of Scienc

Presentation modality influences behavioral measures of alerting, orienting, and executive control

The Attention Network Test (ANT) uses visual stimuli to separately assess the attentional skills of alerting (improved performance following a warning cue), spatial orienting (an additional benefit when the warning cue also cues target location), and executive control (impaired performance when a target stimulus contains conflicting information). This study contrasted performance on auditory and visual versions of the ANT to determine whether the measures it obtains are influenced by presentation modality. Forty healthy volunteers completed both auditory and visual tests. Reaction-time measures of executive control were of a similar magnitude and significantly correlated, suggesting that executive control might be a supramodal resource. Measures of alerting were also comparable across tasks. In contrast, spatial-orienting benefits were obtained only in the visual task. Auditory spatial cues did not improve response times to auditory targets presented at the cued location. The different spatial-orienting measures could reflect either separate orienting resources for each perceptual modality, or an interaction between a supramodal orienting resource and modality-specific perceptual processing

South African seaweed aquaculture: A sustainable development example for other African coastal countries

The green seaweed Ulva is one of South Africa's most important aquaculture products, constituting an important feed source particularly for abalone (Haliotis midae L.), and utilized as a bioremediation tool and other benefits such as biomass for biofuel production and for integrated aquaculture. Besides Ulva spp, Gracilaria spp. are also cultivated. Wild seaweed harvest in South Africa totals 7,602 mt, compared to 2,015 mt of cultivated Ulva. To mitigate for the reliance on wild harvesting, the South African seaweed aquaculture industry has grown rapidly over the past few decades. On-land integrated culture units, with paddle-wheel raceways, are now widely viewed as the preferred method of production for the industry. The success of seaweed aquaculture in South Africa is due to a number of natural and human (industrial) factors. The development of the seaweed aquaculture industry has paralleled the growth of the abalone industry, and has been successful largely because of bilateral technology transfer and innovation between commercial abalone farms and research institutions. In South Africa seaweeds have been used commercially as feedstock for phycocolloid production, for the production of abalone feed, and the production of Kelpak and Afrikelp, which are plant-growth stimulants used in the agricultural sector. Additionally, Ulva is being investigated for large-scale biogas production. The South African seaweed industry provides a template that could be used by other coastal African nations to further their undeveloped aquaculture potential

Gene expression studies for the analysis of domoic acid production in the marine diatom Pseudo-nitzschia multiseries

Background: Pseudo-nitzschia multiseries Hasle (Hasle) (Ps-n) is distinctive among the ecologically important marine diatoms because it produces the neurotoxin domoic acid. Although the biology of Ps-n has been investigated intensely, the characterization of the genes and biochemical pathways leading to domoic acid biosynthesis has been limited. To identify transcripts whose levels correlate with domoic acid production, we analyzed Ps-n under conditions of high and low domoic acid production by cDNA microarray technology and reverse-transcription quantitative PCR (RT-qPCR) methods. Our goals included identifying and validating robust reference genes for Ps-n RNA expression analysis under these conditions. Results: Through microarray analysis of exponential- and stationary-phase cultures with low and high domoic acid production, respectively, we identified candidate reference genes whose transcripts did not vary across conditions. We tested eleven potential reference genes for stability using RT-qPCR and GeNorm analyses. Our results indicated that transcripts encoding JmjC, dynein, and histone H3 proteins were the most suitable for normalization of expression data under conditions of silicon-limitation, in late-exponential through stationary phase. The microarray studies identified a number of genes that were up- and down-regulated under toxin-producing conditions. RT-qPCR analysis, using the validated controls, confirmed the up-regulation of transcripts predicted to encode a cycloisomerase, an SLC6 transporter, phosphoenolpyruvate carboxykinase, glutamate dehydrogenase, a small heat shock protein, and an aldo-keto reductase, as well as the down-regulation of a transcript encoding a fucoxanthin-chlorophyll a-c binding protein, under these conditions. Conclusion: Our results provide a strong basis for further studies of RNA expression levels in Ps-n, which will contribute to our understanding of genes involved in the production and release of domoic acid, an important neurotoxin that affects human health as well as ecosystem function.Plymouth State University Graduate Programs OfficeWoods Hole Oceanographic Institution Academic Programs OfficeNew Hampshire IDeA Network of Biological Research Excellence (NH-INBRE)National Center for Research Resources (U.S.) (Grant 5P20RR030360-03)National Institute of General Medical Sciences (U.S.) (Grant 8P20GM103506-03

HIV infection is an independent risk factor for decreased 6-minute walk test distance.

BackgroundAmbulatory function predicts morbidity and mortality and may be influenced by cardiopulmonary dysfunction. Persons living with HIV (PLWH) suffer from a high prevalence of cardiac and pulmonary comorbidities that may contribute to higher risk of ambulatory dysfunction as measured by 6-minute walk test distance (6-MWD). We investigated the effect of HIV on 6-MWD.MethodsPLWH and HIV-uninfected individuals were enrolled from 2 clinical centers and completed a 6-MWD, spirometry, diffusing capacity for carbon monoxide (DLCO) and St. George's Respiratory Questionnaire (SGRQ). Results of 6-MWD were compared between PLWH and uninfected individuals after adjusting for confounders. Multivariable linear regression analysis was used to determine predictors of 6-MWD.ResultsMean 6-MWD in PLWH was 431 meters versus 462 in 130 HIV-uninfected individuals (p = 0.0001). Older age, lower forced expiratory volume (FEV1)% or lower forced vital capacity (FVC)%, and smoking were significant predictors of decreased 6-MWD in PLWH, but not HIV-uninfected individuals. Lower DLCO% and higher SGRQ were associated with lower 6-MWD in both groups. In a combined model, HIV status remained an independent predictor of decreased 6-MWD (Mean difference = -19.9 meters, p = 0.005).ConclusionsHIV infection was associated with decreased ambulatory function. Airflow limitation and impaired diffusion capacity can partially explain this effect. Subjective assessments of respiratory symptoms may identify individuals at risk for impaired physical function who may benefit from early intervention