Comparison of the shear bond strength of new and recycled metallic brackets using different adhesive materials : an in vitro study.

Purpose: To evaluate and compare shear bond strength (SBS) of new and recycled metallic brackets bonded to conditioned and reconditioned enamel, using two different adhesive materials. Materials and methods: 72 extracted sound human premolars were randomly divided into 6 groups. Transbond XT light cured composite (LCC) and Fuji Ortho LC resin-modified glass ionomer (RMGI), were used as adhesive materials. In groups 1 and 2 (control), new brackets were bonded to sound premolars using either LCC or RMGI, respectively. In Groups 3 and 4, new brackets were bonded to reconditioned enamel; and in groups 5 and 6, sandblasted recycled brackets were rebonded to reconditioned enamel. After 5.000 thermal cycles between 5ºC and 55ºC, SBS was evaluated and adhesive remnant on the enamel assessed using the ARI index. Statistical analyses included Shapiro-Wilk, ANOVA, Fligner-Killeen ANOVA and Tukey tests. Results: The statistical analysis showed no significant difference in SBS comparing control and experimental groups for either new or recycled brackets (p = 0.848). The SBS was significantly higher in brackets bonded with LCC (15.7 MPa) than RMGI (11.6 MPa) (p = 0.006). Adhesive failure was the most frequent, with the adhesive remnant covering more than 50% of the bracket base. Conclusion: No significant differences were observed in SBS using either new or recycled brackets, regardless of the dental surface treatment (conditioned or reconditioned). Significantly higher SBS values were obtained with LCC adhesive. Adhesive failure prevails in all groups.

Risk factors for infectious pancreatic necrosis in farmed Chilean Atlantic salmon (Salmo salar L.) from 2010 to 2013.

Infectious pancreatic necrosis (IPN) is a widespread and economically devastating fish disease caused by infection with a virus referred to as IPN virus (IPNv). In Chile, the disease is endemic and prevalent in both fresh- and salt-water farms affecting cultured salmonids, mainly Atlantic salmon. Here, we present the results of a retrospective cohort study of Atlantic salmon farms stocked between 2010 and 2013, aimed at quantifying the extent to which certain epidemiological factors influence the time interval between stocking and onset of IPN mortality (time to mortality, ttm) in marine farms. Six variables were retained in a final multivariable Cox proportional hazard model. Compared to the 2010 stocking year, ttm was shorter for salmon stocked in years 2012 (HR = 2.1; p = 0.005) and 2013 (HR = 4.3; p = 0.01). The number of salmon farms within a 10-km radius (HR = 1.07; p = 0.002), positive report of IPN in the previous production cycle (HR = 1.95; p = 0.006), three or more smolt batches (HR = 2.27; p < 0.001), and positive report of mortality attributable to BKD (HR = 2.02; p < 0.001) were also associated with low ttm; conversely, ttm was longer for farms that stocked heavier fish (HR = 0.94; p = 0.001). The results presented here were consistent with early studies of IPN epidemiology in Norway and Scotland. Some of the risk factors identified in this study also influenced the risk for other diseases, such as infectious salmon anemia, suggesting that implementation of selected management practices may help to mitigate the burden of important infectious diseases of salmon in Chile.

Melanoma cutáneo de la región dorsal. reporte de un caso / Cutaneous melanoma of the dorsal region.a case report

RESUMEN: El melanoma es una neoplasia que se origina de los melanocitos, células derivadas de la cresta neural. En el Ecuador, entre el 2001 y 2005 se diagnosticaron en Quito en promedio: 18 casos anuales de melanoma en hombres y 26 casos en mujeres, con una tasa de incidencia de 2.5 y 3.2 respectivamente, mientras queen Guayaquil, durante el período 2003-2006 fueron reportados 49 casos en total, con una incidencia de 0.9 por cada 100.000 habitantes en hombres y 0.1 en mujeres. Siempre que se pueda es preferible una biopsia escisional, extirpando la lesión entera. La determinación del ganglio centinela junto al nivel de Clark, el espesor de Breslow y la ulceración del tumor, son considerados los factores pronósticos más importantes del melanoma maligno.

SUMMARY: Melanoma is a neoplasm that originates from the melanocytes, cells derived from the neural crest. In Ecuador, between 2001 and 2005 an average of 18 cases in men and 26 cases in women were diagnosed in Quito, with an incidence rate of 2.5 and 3.2 respectively, while in Guayaquil, during the period 2003-2006, 49 cases were reported, with an incidence of 0.9 per 100.000 inhabitants in men and 0.1 in women. The exact etiology is not clear, it is considered a heterogeneous diseasewith multifactorial origin. Whenever possible, an excisional biopsy is preferable, removing the entire lesion. The determination of the sentinel lymph node along with the Clark level, the Breslow thickness and the ulceration of the tumor, are considered the most important prognostic factors of malignant melanoma.

Tool for predicting Caligus rogercresseyi abundance on salt water salmon farms in Chile.

Caligus rogercresseyi is a host-dependent parasite that affects rainbow trout and Atlantic salmon in Chile. Numbers of sea lice on fish increase over time at relatively predictable rates when the environment is conducive to the parasite's survival and fish are not undergoing treatment. We developed a tool for the salmon industry in Chile that predicts the abundance of adult sea lice over time on farms that are relatively isolated. We used data on sea louse abundance collected through the SalmonChile INTESAL sea lice monitoring program to create series of weekly lice counts between lice treatment events on isolated farms. We defined isolated farms as those with no known neighbors within a 10 km seaway distance and no more than two neighbors within a 20 km seaway distance. We defined the time between sea lice treatments as starting the week immediately post treatment and ending the week before a subsequent treatment. Our final dataset of isolated farms consisted of 65 series from 32 farms, between 2009 and 2015. Given an observed abundance at time t = 0, we built a model that predicted 8 consecutive weekly sea louse abundance levels, based on the preceding week's lice prediction. We calibrated the parameters in our model on a randomly selected subset of training data, choosing the parameter combinations that minimized the absolute difference between the predicted and observed sea louse abundance values. We validated the parameters on the remaining, unseen, subset of data. We encoded our model and made it available as a Web-accessible applet for producers. We determined a threshold, based on the upper 97.5% predictive interval, as a guideline for producers using the tool. We hypothesize that if farms exceed this threshold, especially if the sea lice levels are above this threshold 2 and 4 weeks into the model predictions, the sea louse population on the farm is likely influenced by sources other than lice within the farm.

Consenso Mexicano para el Tratamiento de la Hepatitis C / The Mexican consensus on the treatment of Hepatitis C

El objetivo del Consenso Mexicano para el Tratamiento de la Hepatitis C fue el de desarrollar un documento como guía en la práctica clínica con aplicabilidad en México. Se tomó en cuenta la opinión de expertos en el tema con especialidad en: gastroenterología, infectología y hepatología. Se realizó una revisión de la bibliografía en MEDLINE, EMBASE y CENTRAL mediante palabras claves referentes al tratamiento de la hepatitis C. Posteriormente se evaluó la calidad de la evidencia mediante el sistema GRADE y se redactaron enunciados, los cuales fueron sometidos a voto mediante un sistema modificado Delphi, y posteriormente se realizó revisión y corrección de los enunciados por un panel de 34 votantes. Finalmente se clasificó el nivel de acuerdo para cada oración. Esta guía busca dar recomendaciones con énfasis en los nuevos antivirales de acción directa y de esta manera facilitar su uso en la práctica clínica. Cada caso debe ser individualizado según sus comorbilidades y el manejo de estos pacientes siempre debe ser multidisciplinario.

The aim of the Mexican Consensus on the Treatment of Hepatitis C was to develop clinical practice guidelines applicable to Mexico. The expert opinion of specialists in the following areas was taken into account: gastroenterology, infectious diseases, and hepatology. A search of the medical literature was carried out on the MEDLINE, EMBASE, and CENTRAL databases through keywords related to hepatitis C treatment. The quality of evidence was subsequently evaluated using the GRADE system and the consensus statements were formulated. The statements were then voted upon, using the modified Delphi system, and reviewed and corrected by a panel of 34 voting participants. Finally, the level of agreement was classified for each statement. The present guidelines provide recommendations with an emphasis on the new direct-acting antivirals, to facilitate their use in clinical practice. Each case must be individualized according to the comorbidities involved and patient management must always be multidisciplinary.

Animal production, animal health and food safety: Gaps and challenges in the chilean industry.

This paper summarizes the gaps and challenges related to animal production, health, and food safety as discussed by a panel at the 1st International Symposium of Food Safety (ISFS) in Santiago, Chile, in December 2016. Participating representatives of academia, industry, and government and statements from the audience confirmed that food safety is essential for increasing food security. First, panelists identified the need for a science-based regulatory framework to implement effective regulations. Second, they highlighted the importance of a risk analysis framework to quantify the risk of the potential for antimicrobial resistance associated with the use of antimicrobials, and the need of studies to evaluate foodborne prevention/control strategies. Third, the challenges of filling the gaps between industry and academia were addressed, including examples of successful collaboration, opportunities, and weakness identified by industry. Finally, challenges in animal food production included issues related to changing consumer preferences, animal welfare, the use of antimicrobials, and sustainable animal production. The symposium provided a regional platform to share experiences from the implementation of methods and approaches for food safety. The roundtable successfully explored the future science and technology challenges that are of strategic importance for Chile and the region in animal health and food safety.

Assessing concentration of antibiotics in tissue during oral treatments against piscirickettsiosis.

The use of antimicrobials in aquaculture is increasingly being scrutinized. In Chile, piscirickettsiosis accounts for approximately 90% of the total volume of antibiotics used in marine aquaculture. Treatment failures are frequently reported, but there is limited information on why this occurs. Fish producers have started assessing the level of antibiotics in fish tissues during and immediately after in-feed treatments to determine if they are adequately medicating their fish. In this study, we evaluated the probability of finding antibiotic concentrations in muscle tissue above the minimum inhibitory concentration for 90% of the P. salmonis isolates (MIC90) recently tested in Chile, for two antibiotics commonly used in aquaculture. We found that the proportion of fish with antibiotic concentrations above the MIC90 varied, depending on the product used, species, day of sample collection, and size category of fish within a cage. The proportion of fish above the MIC90 was lower in fish treated with florfenicol than in fish treated with oxytetracycline. Using a mixed-effects logistic model, we modeled the probability of antibiotic concentrations above MIC90 when fish were treated with florfenicol. Our model suggested lower probabilities of having concentrations above MIC90 in Atlantic salmon than in rainbow trout when samples were collected 14 days after the treatment started compared to 7 days, and in the smaller fish within a cage. We discuss these findings and hypothesize about potential issues with treating large populations of fish with in-feed antimicrobials.

The Mexican consensus on the treatment of hepatitis C. / Consenso Mexicano para el Tratamiento de la Hepatitis C.

The aim of the Mexican Consensus on the Treatment of HepatitisC was to develop clinical practice guidelines applicable to Mexico. The expert opinion of specialists in the following areas was taken into account: gastroenterology, infectious diseases, and hepatology. A search of the medical literature was carried out on the MEDLINE, EMBASE, and CENTRAL databases through keywords related to hepatitisC treatment. The quality of evidence was subsequently evaluated using the GRADE system and the consensus statements were formulated. The statements were then voted upon, using the modified Delphi system, and reviewed and corrected by a panel of 34 voting participants. Finally, the level of agreement was classified for each statement. The present guidelines provide recommendations with an emphasis on the new direct-acting antivirals, to facilitate their use in clinical practice. Each case must be individualized according to the comorbidities involved and patient management must always be multidisciplinary.

Evaluating the effect of synchronized sea lice treatments in Chile.

The sea louse is considered an important ectoparasite that affects farmed salmonids around the world. Sea lice control relies heavily on pharmacological treatments in several salmon-producing countries, including Chile. Among options for drug administration, immersion treatments represent the majority of antiparasitic control strategies used in Chile. As a topical procedure, immersion treatments do not induce a long lasting effect; therefore, re-infestation from neighbouring farms may undermine their efficacy. Synchronization of treatments has been proposed as a strategy to improve immersion treatment performance, but it has not been evaluated so far. Using a repeated-measures linear mixed-effect model, we evaluated the impact of treatment synchronization of neighbouring farms (within 10km seaway distance) on the adult lice mean abundance from weeks 2 to 8 post-treatment on rainbow trout and Atlantic salmon farms in Chile, while controlling for external and internal sources of lice before the treatments, and also for environmental and fish-related variables. Results indicate that treatment synchronization was significantly associated with lower adult lice levels from weeks 5 to 7 after treatment. This relationship appeared to be linear, suggesting that higher levels of synchronization may result in lower adult sea lice levels during these weeks. These findings suggest that synchronization can improve the performance of immersion delousing treatments by keeping sea lice levels low for a longer period of time. Our results may be applicable to other regions of the world where immersion treatments are widely used.

Area contact networks and the spatio-temporal spread of infectious salmon anemia virus (ISAV) in Chile.

Area management, the coordination of production and biosecurity practices across neighboring farms, is an important disease control strategy in aquaculture. Area management in aquaculture escalated in prominence in response to outbreaks of infectious salmon anemia (ISA) internationally. Successes in disease control have been attributed to the separation achieved through area-level synchronized stocking, fallowing, movement restrictions, and fomite or pest control. Area management, however, is costly; often demanding extra biosecurity, lengthy or inconveniently timed fallows, and localization of equipment, personnel, and services. Yet, this higher-order organizational structure has received limited epidemiologic attention. Chile's National Fisheries and Aquaculture Service instigated area management practices in response to the 2007 emergence of ISA virus (ISAV). Longitudinal data simultaneously collected allowed retrospective evaluation of the impact of component tenets on virus control. Spatiotemporal analyses identified hydrographic linkages, shared ports, and fish transfers from areas with recent occurrence of ISAV as the strongest predictors of virus spread between areas, though specifics varied by ISAV type (here categorized as HPR0 for the non-virulent genotypes, and HPRv otherwise). Hydrographic linkages were most predictive in the period before implementation of enhanced biosecurity and fallowing regulations, suggesting that viral load can impact spread dynamics. HPR0 arose late in the study period, so few HPRv events were available by which to explore the hypothesis of HPR0 as progenitor of outbreaks. However, spatiotemporal patterns in HPRv occurrence were predictive of subsequent patterns in HPR0 detection, suggesting a parallel, or dependent, means of spread. Better data precision, breadth and consistency, common challenges for retrospective studies, could improve model fit; and, for HPR0, specification of diagnostic test accuracy would improve interpretation.

Sensitivity of Caligus rogercresseyi (Boxshall and Bravo 2000) to pyrethroids and azamethiphos measured using bioassay tests-A large scale spatial study.

The variety of antiparasitics that can be used against caligid copepods is limited and efforts are needed to maintain their efficacies. The objective of this study was to monitor the sensitivity of Caligus rogercresseyi, populations towards antiparasitics based on deltamethrin, cypermethrin and azamethiphos within and across geographic regions. The bioassay design consisted of exposing parasites collected from 23 farms to the different chemotherapeutants at the concentration and exposure times recommended for field treatment, under laboratory conditions, and evaluating the number of dead and live parasites 48h after exposure. Parasites were collected from 23 farms distributed in four macrozones in the Los Lagos region and three macrozones in the Aysén region. Parasite sensitivity was evaluated using a Generalized Linear Mixed Model of the Binomial family (Logit) fit by the maximum likelihood, using the lme4 package in R. Parasite gender, macrozone, and antiparasitics were used as fixed factors and farm was the random factor. The model including all the factors proved to be a useful tool for predicting parasite sensitivity. This approach identified (i) those macrozones with a greater likelihood of finding parasite populations which are more or less sensitive to the three antiparasitics, (ii) cases in which parasite sensitivity to the different antiparasitics varied within a given macrozone, (iii) differences in sensitivity between females and males and (iv) an important random effect associated with farm. The results indicate a spatial variability of parasite sensitivity to antiparasitics which, added to the continuous treatments applied on farms, suggest it is necessary to regularly update the sensitivity status in the macrozones. This would allow managers to improve their decision making processes regarding the type of antiparasitic to be used in a given situation. The one-concentration type bioassay performed in this study allowed us to perform a large spatial study with replicated tests of the sensitivity of C. rogercresseyi to pyrethroids and azamethiphos. Further studies should focus on the farm effects, the relationship between the sensitivity of parasites and field efficacy, as well as parasite population structure and connectivity with regard to parasite transmission between farms.

Risk factors perceived predictive of ISA spread in Chile: applications to decision support.

Aquaculture is anticipated to be a critical element in future solutions to global food shortage. However, diseases can impede industry efficiency and sustainability. Consequently, diseases can and have led to dramatic re-structuring in industry or regulatory practices. The emergence of infectious salmon anemia (ISA) in Chile is one such example. As in other countries, many mitigations were instituted universally, and many incurred considerable costs as they introduced a new layer of coordination of farming activities of marine sites within common geographic areas (termed 'neighborhoods' or 'barrios'). The aggregate response led to a strong reduction in ISA incidence and impact. However, the relative value of individual mitigations is less clear, especially where response policies were universally applied and retrospective analyses are missing 'controls' (i.e., areas where a mitigation was not applied). Further, re-focusing policies around disease prevention following resolution of an outbreak is important to renew sustainable production; though, again, field data to guide this shift in purpose are often lacking. Expert panels can offer timely decision support in the absence of empirical data. We convened a panel of fish health experts to weight risk factors predictive of ISA virus (ISAV) introduction or spread between Atlantic salmon barrios in Chile. Barrios, rather than sites, were the unit of interest because many of the new mitigations operate at this level and few available studies examine their efficacy. Panelists identified barrio processing plant biosecurity, fallowing strategies, adult live fish transfers, fish and site density, smolt quality, hydrographic connection with other neighborhoods, presence of sea lice (Caligus rogercresseyi), and harvest vessel biosecurity as factors with the greatest predictive strength for ISAV virulent genotype ('HPR-deleted') occurrence. Fewer factors were considered predictive of ISAV HPR0 genotype ('HPR0') occurrence, with greatest strengths assigned to fish and site density, adult live fish transfers, and smolt facility HPR0 status. Field validation based on ISAV and risk factor occurrence after panel completion generally supports expert estimates, and highlights a few factors (e.g., broodstock HPR0 status) less conclusive in the original study. Results inform legislation, industry best management practices and surveillance design.

Understanding sources of sea lice for salmon farms in Chile.

The decline of fisheries over recent decades and a growing human population has coincided with an increase in aquaculture production. As farmed fish densities increase, so have their rates of infectious diseases, as predicted by the theory of density-dependent disease transmission. One of the pathogen that has increased with the growth of salmon farming is sea lice. Effective management of this pathogen requires an understanding of the spatial scale of transmission. We used a two-part multi-scale model to account for the zero-inflated data observed in weekly sea lice abundance levels on rainbow trout and Atlantic salmon farms in Chile, and to assess internal (farm) and external (regional) sources of sea lice infection. We observed that the level of juvenile sea lice was higher on farms that were closer to processing plants with fish holding facilities. Further, evidence for sea lice exposure from the surrounding area was supported by a strong positive correlation between the level of juvenile sea lice on a farm and the number of gravid females on neighboring farms within 30 km two weeks prior. The relationship between external sources of sea lice from neighboring farms and juvenile sea lice on a farm was one of the strongest detected in our multivariable model. Our findings suggest that the management of sea lice should be coordinated between farms and should include all farms and processing plants with holding facilities within a relatively large geographic area. Understanding the contribution of pathogens on a farm from different sources is an important step in developing effective control strategies.

Prevalencia de neuropatía periférica en diabéticos tipo 2 en el primer nivel de atención / Prevalence of peripheral neuropathy among primary care type 2 diabetic patients

Background: Neuropathy is a common complication of diabetic patients. Aim: To determine the prevalence of diabetic peripheral neuropathy in Type 2 diabetic patients attended at a family medicine unit. Material and Methods: Cross-sectional assessment of 348 type 2 diabetic patients aged 34-89 years (60% females) with a disease duration of 5 to 15 years. Peripheral neurological status was evaluated using The Michigan Neuropathy Screening Instrument, a tool that includes a self-assessment of symptoms and a physical examination. Results: Diabetic neuropathy was found in 240patients (69%). The prevalence in males and females was 72 and 67% respectively. The prevalence in patients with a disease duration of 5, 10 and 15 years, was 59, 69 and 77%, respectively. Fifty percent of patients with neuropathy complained of dry skin, 2% had ulcers, 43% had an abnormal perception of vibration and 29% had an abnormal monofilament test. Conclusions: The overall prevalence of peripheral neuropathy in this group of patients was 69% and was directly associated with the duration of the disease.

"Familias fuertes" taller de fortalecimienmto para adolescentes: satisfacción con la educación recibida / "Strong families": a workshop to strengthen adolescent families. Outcome satisfaction

Objective: This study examined family satisfaction with the education they received in the Strong Families Workshop, whose purpose is risk behavior prevention in adolescents aged 10 to 14. Patients and Method: This was a descriptive, cross-sectional study involving 100 families (parents or guardians and adolescents) from five high schools in the Metropolitan Region of Santiago, Chile. The workshop consisted of seven sessions for parents, adolescents and families. An instrument was used on participants at 6 months post intervention. It included aspects relating to the structure, process and results of the workshop. Results: 100 percent of the families attended the complete workshop. The degree of satisfaction with the family sessions in both groups was greater than 90 percent, and greater than 80 percent with respect to the schedule, frequency, quality of videos, written program material, teacher quality and content completion achievements. Conclusions: There is great interest on the part of parents and adolescents to jointly participate in family strengthening workshops. This may justify the implementation of such at the school level, considering the role of educators as promoters of health and the family as a protective factor in healthy adolescent development.

Objetivo: Este trabajo estudió la satisfacción en familias con la educación recibida en el Taller Familias Fuertes, cuyo propósito es la prevención de conductas de riesgo en adolescentes de 10 a 14 años. Pacientes y Método: Estudio descriptivo, transversal, en 100 familias (padres o tutores y adolescentes) de cinco colegios de la Región Metropolitana de Santiago de Chile. El taller, constó de siete sesiones para padres, adolescentes y familia. Se aplicó un instrumento a los participantes a los 6 meses post intervención, que consideró aspectos de la estructura, proceso y resultados del taller. Resultados: El 100 por ciento de las familias asistió a la totalidad del taller. El grado de satisfacción en ambos grupos con la sesiones en familia fue mayor al 90 por ciento y mayor al 80 por ciento respecto del horario, frecuencia, vídeos, material escrito del programa, calidad docente y logros del cumplimiento de los contenidos. Conclusiones: Existe un gran interés de padres y adolescentes en participar en forma conjunta en talleres de fortalecimiento familiar, por lo tanto se justifica ampliar su implementación a nivel escolar considerando el rol de los educadores como agentes promotores de la salud y a la familia como un factor protector del desarrollo sano del adolescente.

Organophosphate pesticides increase the expression of alpha glutathione S-transferase in HepG2 cells.

Chlorpyrifos and methyl parathion are among the most widely used insecticides in the world. Human populations are constantly exposed to low doses of both due to their extensive use and presence in food and drinking water. Glutathione S-transferase (GST) catalyzes the conjugation of glutathione on electrophilic substrates and is an important line of defense in the protection of cellular components from reactive species. GST alpha1 (GSTA1) is the predominant isoform of GST expressed in the human liver; thus, determining the effect of insecticides on GSTA1 transcription is very important. In the present study, we analyzed the effects of methyl parathion and chlorpyrifos on GSTA1 gene expression in HepG2 cells using real time PCR, and activity and immunoreactive protein assays. The results demonstrated that exposure to methyl parathion and chlorpyrifos increased the level of GSTA1 mRNA, GSTA1 immunoreactive protein and GST activity relative to a control. These results demonstrated that these insecticides can increase the expression of GSTA1. In conclusion, HepG2 cell cultures treated with methyl parathion and chlorpyrifos could be a useful model for studying the function of GSTA1 and its role in the metabolism of xenobiotics in the liver.

Endohelminth parasites from salmonids in intensive culture from southern Chile.

A total of 228 salmonids (90 Oncorhynchus mykiss, 48 Oncorhynchus kisutch, and 90 Salmo salar) from 8 intensive aquaculture centers in the south of Chile were examined for endohelminths parasites between December 2008 and May 2009. The body cavities of 2 O. mykiss were infected by Diphyllobothrium sp. plerocercoids (prevalence: 6.7%, mean intensity: 1.0, mean abundance: 0.07) from the Lake Tarahuin hatchery on the south of Chiloé Island. Also, tetraphyllidean plerocercoids (prevalence: 3.3%, mean intensity: 1, mean abundance: 0.03) and fourth-stage larvae of Hysterothylacium aduncum (prevalence: 6.7%, mean intensity: 1, mean abundance 0.07) were observed in O. kisutch from a marine hatchery in Chiloé. The occurrences of Diphyllobothrium sp. in a lake and a tetraphyllidean plerocercoid from marine cultured salmonid in Chiloé are reported for first time. No muscular infection by helminths was recorded in the fish examined.

Daily cycle and body characteristics of mating Litopenaeus vannamei shrimps (Decapoda: Penaeidae) in the wild off southern Sinaloa, Mexico

Mating behavior has been described for very few species of penaeoid shrimps. We describe some of the environmental conditions under which mating of Litopenaeus vannamei took place in the ocean, as inferred by the presence of attached spermatophores on the thelycum of females, combined with the presence of mature males with empty ampulla terminalis, both evidence of recent copulation. Out of a total of twelve 24 hr samplings on board the research vessel B/O "EL PUMA", one was selected to examine mating. There were four periods of observation. The highest frequency of females with attached spermatophores were found during the daytime whilst the lowest was registered during the night. Females with attached spermatophore were mostly at stages IV and V of ovarian maturity and fell within the 30-50 mm of C.L. range. Copulating male size ranged between 30 and 40 mm of C.L. and there was a close relation between the percentage of mating females and males. Male to female ratio varied throughout the sampling period but it was never 1:1. The female mean size was, in all cases, bigger than the male mean size. Among the environmental factors, salinity and oxygen varied very slightly throughout the sampling period; temperature variation was more pronounced and those changes were attributed to the tidal oscillation.

Daily cycle and body characteristics of mating Litopenaeus vannamei shrimps (Decapoda: Penaeidae) in the wild off southern Sinaloa, Mexico.

Mating behavior has been described for very few species of penaeoid shrimps. We describe some of the environmental conditions under which mating of Litopenaeus vannamei took place in the ocean, as inferred by the presence of attached spermatophores on the thelycum of females, combined with the presence of mature males with empty ampulla terminalis, both evidence of recent copulation. Out of a total of twelve 24 hr samplings on board the research vessel B/O "EL PUMA", one was selected to examine mating. There were four periods of observation. The highest frequency of females with attached spermatophores were found during the daytime whilst the lowest was registered during the night. Females with attached spermatophore were mostly at stages IV and V of ovarian maturity and fell within the 30-50 mm of C.L. range. Copulating male size ranged between 30 and 40 mm of C.L. and there was a close relation between the percentage of mating females and males. Male to female ratio varied throughout the sampling period but it was never 1:1. The female mean size was, in all cases, bigger than the male mean size. Among the environmental factors, salinity and oxygen varied very slightly throughout the sampling period; temperature variation was more pronounced and those changes were attributed to the tidal oscillation.