Universidade Nilton Lins

Studies determining the feeding habits of fish are essential for understanding the relationships between fauna components and other aquatic organisms. This study aimed to evaluate the feeding habits of the Arowana Osteoglossum bicirrhosum in the Piranha Sustainable Development Reserve, located in the middle Solimões River, Amazonas state. The research covered different phases of the flood pulse (recession, flooding, flood peak, and dry phase) from September 2015 to May 2016. One hundred stomach samples were collected, with an average standard weight and length of 684.81 ± 257.73g and 44.92 ± 5.91cm, respectively, showing a high Pearson correlation coefficient (p= 0.9373905). Stomach content analysis revealed that 76% of the samples contained food, with 72% consisting of arthropods, 13% plant remains, 10% fish, 3% reptiles, and 2% mammals. The alternation of periods influenced the bioavailability of food in the aquatic environment, with arthropods, mainly insects, being identified as the primary food source for the Arowana. This indicates a generalist and opportunistic feeding behavior with a diet tending towards insectivory.

BACKGROUND Truenat™ is a WHO-recommended rapid molecular test for diagnosing TB and detecting rifampicin resistance, whose performance has been evaluated in a few high TB burden countries. METHODS A prospective multicentre study was conducted in Brazil to estimate the sensitivity and specificity of Truenat MTB Plus compared to Xpert® MTB/RIF Ultra for detecting pulmonary TB. Liquid culture for Mycobacterium tuberculosis and drug susceptibility testing were used as reference. RESULTS Among 283 participants, 112 (39.6%) had culture-positive pulmonary TB. The sensitivity and specificity of Truenat MTB Plus were respectively 72.7% (95% CI 63.41–80.78) and 99.4% (95% CI 96.71–99.98), compared to 78.4% (95% CI 69.56–85.63) and 99.4% (95% CI 96.67–99.98) for Xpert MTB/RIF Ultra. In 89 people living with HIV (PLHIV), Truenat MTB Plus showed a sensitivity of 45.0% (95% CI 23.06–68.47) and specificity of 100.0% (95% CI 95.64–100.00). Among 71 patients previously treated for TB, Truenat MTB Plus showed sensitivity and specificity of respectively 79.3% (95% CI 60.28–92.01) and 97.5% (95% CI 86.84–99.94). Xpert MTB/RIF Ultra detected rifampicin resistance in 11/88 samples (12.5%) vs 9/72 (12.5%) with Truenat MTB Plus. CONCLUSION The Truenat MTB Plus performance was comparable to Xpert MTB/RIF Ultra. Both tests demonstrated lower sensitivity in PLHIV.

Feed restriction can be used as a management strategy to increase feed efficiency through compensatory growth (a higher growth rate after a period of restricted feeding). However, there is still a lack of information on the physiological mechanisms underlying the fish responses to feed restriction. Therefore, this study aimed at investigating the cycles of fasting and refeeding on the performance, cost feeding, health and physiological mechanisms of juvenile tambaqui (Colossoma macropomum). For this purpose, feeding protocols were tested for 60 days: continuous feeding (control); two days of fasting and refeeding for two days (F2R2); two days of fasting and refeeding for three days (F2R3) and two days of fasting and refeeding for four days (F2R4), on a total of 108 two-month-old tambaqui juveniles (29.53 ± 1.31 g), distributed in 300 L boxes. Weight gain (g) was lower for the F2R2 and F2R3 treatments compared to the control. Fish subjected to the F2R4 feeding strategy showed similar growth to the group of fish continuously fed. Only the restriction protocol F2R3 resulted in a reduction in blood glucose, while cholesterol was reduced in F2R2 and F2R3. There was mobilization of hepatic glycogen in the F2R3 and F2R4 treatments, while muscle lipids were not altered. The different fasting cycles did not affect leukocyte respiratory activity, hematocrit or hemoglobin. The lowest relative feed cost values were in the F2R2 and F2R4 treatments. The F2R4 protocol reduces feed cost and maintains the ability to adjust energy metabolism without causing stress in C. macropomum. Keywords: compensatory growth; metabolism; tambaqui

Infections with Flavobacterium oreochromis pose risks to the production of Colossoma macropomum. Since no therapeutic treatment exists for this disease in this aquatic host, prophylaxis through vaccination is one method for disease control. The enzyme-linked immunosorbent assay (ELISA) is widely used in aquaculture to assess animal immunity and, mainly, to validate vaccination protocols. The method based on the use of immunoglobulin Y (IgY) is an alternative to mammalian antibodies that should be considered due to its advantages over antibodies produced by small mammals. This study aimed to standardize an indirect ELISA (iELISA) protocol to validate the immunization of C. macropomum against F. oreochromis. For this, a hen and fish were immunized to obtain anti-C. macropomum and anti-F. oreochromis antibodies, respectively, which were used to standardize the test. Fish were inoculated with bacterin + adjuvant, bacterin alone, adjuvant alone, or phosphate-buffered saline, subjected to blood sampling, and monitored for up to 60 days. The iELISA was composed of the inactivated bacteria in the coating step, C. macropomum anti-Flavobacterium oreochromis as the primary antibody, and anti-C. macropomum IgY as the secondary antibody. The results demonstrate that the highest antibody titers were found in the organisms immunized with bacterin + adjuvant and bacterin. The iELISA enabled the detection of antibodies produced by C. macropomum, which were mediated by IgY specificity.

This study aimed to assess the impact of dietary supplementation with Schizochytrium sp. meal, a source of docosahexaenoic acid (DHA), on the growth, hemato-biochemical parameters, and fatty acid composition of juvenile pirarucu (Arapaima gigas). Two diets were used: a test diet (5%SZ) and a control diet (0 SZ). Juvenile pirarucu (561.3 ± 13.4 g; 47.5 ± 7.1 cm) were kept in recirculating aquaculture tanks and fed three times daily for 12 weeks. No significant differences in growth performance or adverse effects on hemato-biochemical parameters were found, except for hemoglobin and total protein. The fatty acid profile of the fillets from the fish fed the 5 SZ diet mirrored that of the Schizochytrium sp. meal, with increased levels of palmitic acid, DHA, and eicosapentaenoic acid (EPA), and decreased levels of linoleic and linolenic acids. The inclusion of Schizochytrium sp. meal reduced monounsaturated fatty acids from 39.6% to 32.0% and increased highly unsaturated fatty acids from 3.05% to 11.9% of total lipids. The DHA content was 9.45 times higher in the fillets of the fish fed 5 SZ, improving the n-3/n-6 ratio from 0.26 to 1.19. In conclusion, adding 5% Schizochytrium sp. meal enhances the nutritional quality of pirarucu fillets by increasing DHA and the n-3/n-6 ratio.

Edible mushrooms have been used as sustainable sources of proteases of industrial interest. The aim of this research was to investigate the influence of different culture media on mycelial growth and the potential of an Amazonian mushroom species, Auricularia fuscosuccinea DPUA 1624, in the biosynthesis of bovine milk coagulant enzymes. The species was cultivated on Sabouraud agar, malt, glucose, and peptone agar, malt extract agar, and glucose and peptone agar, supplemented with yeast extract for mycelial development. Enzyme biosynthesis was evaluated by submerged fermentation. Subsequently, the cultures were incubated at 28 °C for 8 days. Proteolytic and coagulant activities were determined using 1% azocasein solution and milk powder as substrates, respectively. In the results of radial growth speed of A. fuscosuccinea, the values were significant in the GYP and SAB + YE culture media. However, GYP agar favored the growth and mycelial vigor of A. fuscosuccinea; therefore, this medium was selected to obtain inoculum in the tests. In submerged fermentation, the MGYP medium favored the synthesis of proteases for A. fuscosuccinea and synthesized coagulant proteases in 100% of the media, in which significant activity was observed in SAB + YE. The significant production of coagulant proteases of A. fuscosuccinea was obtained under the following conditions: inoculum size 10%, 8 days of fermentation period, and 8 days of inoculum age. The results indicate that A. fuscosuccinea DPUA 1624 has potential for use in industrial manufacturing, especially in dairy products.

Background: We compared the enzymatic, coagulant, and neuromuscular activities of two variants (yellow—CDRy and white—CDRw) of Crotalus durissus ruruima venom with a sample of C. d. terrificus (CDT) venom and examined their neutralization by antivenom against CDT venom. Methods: The venoms were screened for enzymatic and coagulant activities using standard assays, and electrophoretic profiles were compared by SDS-PAGE. Neutralization was assessed by preincubating venoms with crotalic antivenom and assaying the residual activity. Results: SDS-PAGE showed that the venoms had similar electrophoretic profiles, with the main bands being phospholipase A2 (PLA2), serine proteinases, L-amino acid oxidase (LAAO), and phosphodiesterase. CDRy venom had the highest proteolytic and LAAO activities, CDRw venom had greater PLA2 and esterolytic activities at the highest quantity tested, and CDT had greater PLA2 activity than CDRy. CDRw and CDT venoms had similar proteolytic and LAAO activities, and CDRy and CDT venoms had comparable esterolytic activity. None of the venoms altered the prothrombin time (PT), but all of them decreased the activated partial thromboplastin time (aPPT); this activity was neutralized by antivenom. The minimum coagulant dose potency was CDRw >> CDRy > CDT. All venoms had thrombin-like activity that was attenuated by antivenom. CDRy and CDRw venoms showed α-fibrinogenolytic activity. All venoms partially cleaved the β-chain. CDRy and CDT venoms caused neuromuscular facilitation (enhanced muscle contractions) followed by complete blockade, whereas CDRw venom caused only blockade. Antivenom neutralized the neuromuscular activity to varying degrees. Conclusions: These findings indicate that while CDR and CDT venoms share similarities, they also differ in some enzymatic and biological activities and in neutralization by antivenom. Some of these differences could influence the clinical manifestations of envenomation by C. d. ruruima and their neutralization by the currently used therapeutic antivenom.

This study evaluated the performance of the lambari-do-rabo-amarelo Astyanax bimaculatus fed diets containing BSF adult fly meal, replacing fishmeal. Two hundred juveniles were distributed in 20 tanks, with five levels of substitution (0%, 12.5%, 25%, 37.5%, and 50%) for 45 days. The diets were isoproteic and isoenergetic, provided to the animals three times a day. The results showed that the increased substitution impaired the fish's performance, with the highest weight gain in the treatment without substitution (0%). Feed conversion, protein efficiency, and energy efficiency decreased due to the high chitin content of the adult fly. It is concluded that BSF fly meal is not advantageous for the lambari-do-rabo-amarelo.

Extreme temperature events brought on by climate change are occurring more frequently and with greater intensity, which has an impact on all economic activities, including aquaculture. The chapter brings insights into the effect of climate change on the aquaculture industry as well as future research on the topic, exploring specific questions: What possible repercussions can climate change have on the parasite–host dynamic in aquaculture? How is the relationship between the host, biological agents, and environment? Climate change induces alterations in the physical–chemical parameters of the water, impacting all current ecological interactions and maybe limiting fish physiology and development throughout the whole aquaculture process. Through hosts and/or biological agents, fish health is predicted to be more impacted by climate change.

Background Bothrops venom consists primarily of metalloproteinase and phospholipase A2 toxins, which are responsible for the acute inflammatory, coagulant and hemorrhagic action following snakebite. The local effects of snakebite envenomation by Bothrops species are particularly prevalent yet poorly studied, but include pain, edema, erythema, blistering, bleeding, and ecchymosis. Methods and findings In this study, we describe the dermatopathological findings observed in a series of 22 patients diagnosed with Bothrops envenomation treated in a tertiary hospital of Manaus, in the Brazilian Amazon. Clinically, pain and edema were observed in all patients, followed by fang marks (63.6%), secondary infection (36.3%), ecchymosis (31.8%), erythema (22.7%), blister (13.6%), and necrosis (4.5%). Regarding histopathological findings, epidermal alterations such as spongiosis, acanthosis and hyperkeratosis were the most observed characteristics in our cases series, with isolated cases of hyperplasia, hemorrhagic intraepidermal blister and severe necrosis. Changes in dermis and hypodermis consisted mainly of hemorrhage, inflammatory infiltrate, edema, congestion, and vascular damage, whereas cases of collagen damage, necrosis, abscess, and signs of tissue repair, indicated by the presence of granulation tissue, were also observed, with a persistence of inflammatory and hemostatic alterations even days after antivenom administration. Therefore, the tissue damage resulting from Bothrops envenomation could be related to both direct venom activity as well as inflammatory response or presence of infectious process. The histopathological analysis of human skin injury can enlighten the pathological and endogenous effects of local envenomation and could underpin new strategies, including novel treatments, adjuvants or changes in clinical management, that lead to better outcomes in snakebite patients.

Background Despite government efforts, tuberculosis (TB) remains a major public health threat in Brazil. In 2023, TB incidence was 39.8 cases per 100,000 population, far above the WHO’s target of 6.7 cases per 100,000. Using national-level datasets, we investigated and forecasted the potential impact of proposed public health interventions aimed at reducing TB incidence in Brazil. Methods Monthly TB surveillance data (January 2018–December 2023) were collected from Brazilian national reporting systems: SINAN-TB (TB cases), SITE-TB (TB drug resistance), and IL-TB (preventive therapy). These data were used to create a multivariable Bayesian Structural Time-Series (BSTS) model, with 5000 Monte-Carlo simulations, which identified key predictors of TB incidence and forecasted these rates from 2024 to 2030 under various scenarios. Findings Vulnerabilities including incarceration, TB-HIV coinfection and TB-diabetes mellitus, as well as coverages of directly observed therapy (DOT), contact investigation and preventive treatment (TPT) completion rates, were identified as key predictors of TB incidence. Under current trends, we forecasted TB incidence in Brazil to be 42.1 [34.1–49.8] per 100,000 person-years by 2030 (mean [95% prediction intervals]). A scenario considering decreases in TB cases among vulnerable populations resulted in an absolute reduction of −10.6 [−9.4 to −12.0] in projected TB incidence. Additional reductions were seen with increased coverage of DOT, TPT adherence, and contact investigation rates (−14.4 [−13 to −16.2]), and by combining these with efforts to reduce TB cases among vulnerable populations (−23.6 [−26.3 to −41.4]), potentially lowering incidence to 18.5 [7.8–28.4] per 100,000, though still above WHO targets. Interpretation Our findings demonstrate that interventions focused on enhancing health policies focused on decreasing TB cases among vulnerable populations, such as individuals with TB-HIV coinfection, incarcerated populations, and those with TB-diabetes comorbidity, along with improvements in health management indicators such as DOT implementation, contact investigation coverage, and TPT completion rates, are effective in reducing TB incidence nationwide. Funding 10.13039/501100006507Oswaldo Cruz Foundation.

The study investigates the economic aspects of red tilapia (Oreochromis sp.) production using biofloc technology under different electrical energy sources. Conducted at the El Vergel Fish Farming Association in Arauca, Colombia, the study examines four energy treatments: conventional energy (CE), combined conventional and photovoltaic energy (CPVE), full photovoltaic energy (PVE), and simulation of photovoltaic energy generating surplus for nighttime use (PVES). The water quality and zootechnical performance met the species requirements, with dissolved oxygen decreasing as fish size increased. The PVE treatment had the highest initial investment due to solar panels and battery costs, but it also had the lowest operating energy costs. However, the overall costs of the PVE treatment increased due to depreciation and maintenance. Feed was the largest production cost, followed by labor in most treatments, while depreciation was a major cost for the PVE treatment. The total operating cost (TOC) of the photovoltaic energy systems (PVE and PVES) was lower compared to that of conventional energy (CE), with PVES showing the highest cost savings. The reduction in energy costs highlights the potential for solar energy systems to enhance the economic viability of aquaculture production, making these systems a favorable option for sustainable production in the long term.

Nile tilapia (Oreochromis niloticus) and tambaqui (Colossoma macropomum) are the two most produced freshwater fishes in Brazil. This study investigated the potential pathogenicity of Streptococcus agalactiae and Francisella orientalis, previously isolated from diseased Nile tilapia, to tambaqui. Experimental infection trials were conducted in juvenile tambaqui at a dose of approximately 10⁷ CFU fish⁻¹, assessing clinical signs, mortality, bacterial recovery, and histopathological changes. Results demonstrated that S. agalactiae exhibited high pathogenicity to tambaqui, causing rapid disease progression, high mortality (83.33%) within 48 h post-infection, and severe lesions in multiple organs, under the experimental conditions. In contrast, F. orientalis infection did not result in mortality or clinical signs, despite bacterial recovery and granulomatous inflammation observed in the tissues. This study highlights the need to consider the potential impact of these pathogens in tambaqui farming.

Leishmaniasis, a disease caused by protozoan Leishmania spp., exhibits a broad range of clinical manifestations. Host resistance or susceptibility to infections is often influenced by the genetic make-up associated with natural immunity. Caspase-1, a key component of the NLRP3 inflammasome, is critical for processing pro-IL-1β into its active form, IL-1β, while CARD8 functions as an NLRP3 inflammasome inhibitor. We conducted a case–control study comparing L. guyanensis-cutaneous leishmaniasis (Lg-CL) patients with healthy individuals (HCs) by analyzing the CASP1 genetic variants rs530537A>G, rs531542C>T, rs531604A>T and rs560880G>T. Additionally, a combined analysis of CARD8rs2043211A>T with CASP1rs530537 was performed. The genotype distribution for the four variants showed no significant differences between Lg-CL patients and HCs. However, the haplotype analysis of the four CASP1 variants identified the GTTT haplotype as associated with a 19% decreased likelihood of Lg-CL development, suggesting a protective effect against disease progression. The combined analysis of CARD8 with CASP1 variants indicated that individuals homozygous for both variants (GG/TT) exhibited a 38% reduced risk of developing Lg-CL (OR = 0.62 [95%CI:0.46–0.83]) in comparison to individuals with other genotype combinations. No correlation was found between the CASP1 variant genotypes and plasma IL-1β levels. CASP1 may act as a genetic modifier in Lg-CL.

Lactococcus spp. has emerged as a pathogen that is affecting global aquaculture, with L. garvieae, L. petauri, and L. formosensis causing piscine lactococcosis. While antimicrobials are commonly used to treat diseases in aquaculture, reports of antimicrobial resistance in fish isolates are increasing. However, little is known about the susceptibility patterns of Lactococcus spp. strains isolated from native fish species in Brazil. This study aimed to assess the antimicrobial susceptibility of these strains and establish a provisional epidemiological cutoff value for L. garvieae using the normalized resistance interpretation approach. A total of 47 isolates were tested: 17 L. garvieae, 24 L. petauri, and 6 L. formosensis. The isolates were classified as wild-type (WT) or non-wild-type (NWT) based on inhibition zone diameters. Isolates classified as NWT for three or more antimicrobial classes were considered multidrug-resistant, and the multiple antibiotic resistance (MAR) index was calculated. The results revealed heterogeneity in antimicrobial resistance profiles, with higher resistance to trimethoprim/sulfamethoxazole and norfloxacin. Resistance to other antimicrobials, including florfenicol and oxytetracycline (approved for use in Brazil), varied according to the bacterial species. Lactococcus petauri (87.5%) and L. formosensis (66.7%) showed the highest multidrug resistance, compared to L. garvieae (11.7%), along with higher MAR index values. These findings suggest that multidrug-resistant strains could pose future challenges in the production of native species, underscoring the need for ongoing monitoring of antimicrobial resistance and responsible use of antimicrobials in aquaculture.

Flavobacterium oreochromis, is associated with high mortality rates in the early stages of tambaqui (Colossoma macropomum) production. This study investigated the genetic effects caused by F. oreochromis infection in tambaqui juveniles by comparing gene expression levels between symptomatic (IS) and asymptomatic (IA) individuals. A bacterial challenge was conducted by intraperitoneal infection of F. oreochromis. A control group (CT) was established where individuals were injected with PBS. During the bacterial challenge, 5 skin samples from IA animals and 4 samples from the IS group were extracted for transcriptome sequencing (RNA-Seq). A pool formed from samples of 5 CT individuals was also sequenced. Approximately 21 million reads per library were aligned to the tambaqui genome (GCA_904425465.1). A differential expression analysis was performed to compare gene expression levels between IA and IS. To control false discovery rates, p-values were adjusted to q-values < 0.05. A total of 2,470 overexpressed genes and 1,305 underexpressed genes were identified in IS, while 1,358 overexpressed genes and 488 underexpressed genes were generated in IA. Genes overexpressed in both conditions were related to autophagy (ATG4B and ULK2) and oxidative stress (KLF9, DDT1, and TXNIP) regulated by the proteasome mechanism. The results suggest that autophagy and oxidative stress are important components of homeostasis and immune defense in tambaqui during the acute phase of F. oreochromis infection. We suggest that the progression of efficient immune mechanisms is limited, possibly due to an imbalance of molecular mechanisms. Further studies are needed to better understand the host-pathogen interaction.

Aim: The study examined how different dry and lubricated polishing protocols impact the gloss, roughness, and material loss of nanoparticle resin composites, before and after simulated toothbrushing. Methods: One hundred cylindrical resin composite specimens were prepared and divided into an unpolished group and three test groups: Dimanto (DIM), Sof-Lex Pop-On (SOF), and Astrobrush (ASTRO). These groups underwent polishing dry, with water, or with or petroleum jelly. Surface parameters including gloss (Novo-Curve – Rhopoint TM, England), roughness, and material loss (MaxSurf XT 20, MahrGoettingen, Germany) were evaluated at four stages: baseline, polishing, simulated toothbrushing, and repolishing. Data were submitted to repeated measures ANOVA (P<0.05). Results: Lubrication did not affect the studied parameters after polishing with DIM. SOF showed improved performance without lubricants, whereas ASTRO achieved higher gloss and lower roughness when lubricated. In terms of surface material loss, DIM exhibited less material loss when used with petroleum jelly, SOF had reduced material loss when used with water, and ASTRO showed the most material loss when lubricated with petroleum jelly. Conclusion: The gloss, roughness, and surface material loss of the nanoparticle resin composite are influenced by the type of polisher used and the choice of lubricant. However, none of the differences observed surpassed the established thresholds for roughness or gloss perception, suggesting that these protocols are potentially viable for clinical application. Despite detectable differences among the polishing systems and lubricant combinations, all tested options are clinically acceptable. None of them exceeded the thresholds for biofilm accumulation or perceptible differences in surface gloss.