Aggressive behaviour traits predict physiological stress responses in Nile tilapia (Oreochromis niloticus)

This study tested whether aggressive behaviour can predict individual variation in stress responses of Nile tilapia Oreochromis niloticus. We used a mirror test to measure tendency to aggressive behaviour, and calculated the attack frequency and time until the first attack (latency) for each fish. One day later, we measured plasma cortisol and glucose, and two days later, we measured ventilatory frequency (VF) (pre-confinement responses). Immediately after the VF measure, we subjected the same fish to 30 min confinement, followed by measurements of cortisol, glucose, and VF (post-confinement responses). We found that post-confinement stress cortisol, glucose, and VF were higher than pre-confinement responses. Attack frequency was negatively correlated with VF and latency was positively correlated with baseline glucose and VF. Thus, we conclude that attack frequency and latency to a mirror reflection could be used to predict baseline levels of physiological stress indicators in Nile tilapia.

Fish ladders select fish traits on migration - still a growing problem for natural fish populations

We investigated the potential selective effect of fish ladders on physiological and morphological profiles of the curimbata, Prochilodus lineatus, during reproductive migration in Brazil. We registered sex, body weight and length, plasma glucose, hepatosomatic and gonadosomatic indices (HSI and GSI, respectively), hematocrit, leucocrit, blood cell and nucleus areas, and the diameter of white and red muscle fibers in fish sampled at the bottom (downstream) and at the top (upstream) of a fish ladder at a hydroelectric dam. Males and females at the top of the ladder showed higher size (weight and length), white muscle fiber diameters, plasma glucose levels and lower hematocrit when compared with those at the bottom. These size and muscle traits assist fish to overcome the ladder barrier and bypass the dam, an effort that might be reflected in the glucose levels. Females also showed higher GSI at the top of the fish ladder, a trait possibly facilitating their reproduction upstream. These results indicate that a dam system favors fish with specific morphological-physiological profile. This may have a strong influence upon upstream fish populations over generations and implies the presence of artificial selective pressure.

Chronic social stress in rainbow trout: Does it promote physiological habituation?

The effect of chronic social stress on growth, energetic substrates and hormones was tested in rainbow trout, Oncorhynchus mykiss. After a 14-day isolation period, the fish were paired for 8 days. In order to expose fish to chronic intermittent social contact during pairing, they were maintained in direct contact with each other during the first day. After that, a black plastic screen partition was introduced in each tank, preventing direct contact between animals. Every day the partition was removed for 30 min, allowing physical interaction between fish. At the end of pairing period, they were isolated again for 13 days. Fish were weighed and blood was sampled frequently during the experiment. Plasma levels of cortisol, growth hormone, glucose, total protein and free amino acids were quantified. Both dominants and subordinates had specific growth rate decreased during the pairing period, but only subordinates increased when the stressor was abolished (dominants: 0.32 +/- 0.21 and 0.24 +/- 0.41, subordinates: -0.77 +/- 0.29 and 0.37 +/- 0.31, respectively). Dominants showed a higher cortisol level one week after pairing condition had been abolished than subordinates (dominants: 56.76 +/- 13.26, subordinates: 31.89 +/- 13.36). We conclude that chronic condition of intermittent social stress represents a stressful condition for animals of both hierarchical ranks and a treatment of one daily short direct contact between conspecifics does not promote habituation in fish, as mentioned for other stressors. (C) 2007 Elsevier B.V. All rights reserved.

The 'club' cell and behavioural and physiological responses to chemical alarm cues in the Nile tilapia

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Morphological and physiological specialization for digging in amphisbaenians, an ancient lineage of fossorial vertebrates

Amphisbaenians are legless reptiles that differ significantly from other vertebrate lineages. Most species dig underground galleries of similar diameter to that of the animal. We studied the muscle physiology and morphological attributes of digging effort in the Brazilian amphisbaenid Leposternon microcephalum (Squamata; Amphisbaenia), which burrows by compressing soil against the upper wall of the tunnel by means of upward strokes of the head. The individuals tested (<72 g) exerted forces on the soil of up to 24 N. These forces were possible because the fibres of the longissimus dorsi, the main muscle associated with burrowing, are highly pennated, thus increasing effective muscle cross-sectional area. The muscle is characterized by a metabolic transition along its length: proximal, medial and distal fibres are fast contracting and moderately oxidative, but fibres closer to the head are richer in citrate synthase and more aerobic in nature. Distal fibres, then, might be active mainly at the final step of the compression stroke, which requires more power. For animals greater than a given diameter, the work required to compress soil increases exponentially with body diameter. Leposternon microcephalum, and probably some other highly specialized amphisbaenids, are most likely constrained to small diameters and can increase muscle mass and effective muscle cross-sectional area by increasing body length, not body diameter.

Locomotor performance of closely related Tropidurus species: relationships with physiological parameters and ecological divergence

Tropidurid lizards have colonized a variety of Brazilian open environments without remarkable morphological variation, despite ecological and structural differences among habitats used. This study focuses on two Tropidurus sister-species that, despite systematic proximity and similar morphology, exhibit great ecological divergence and a third ecologically generalist congeneric species providing an outgroup comparison. We quantified jumping capacity and sprint speed of each species on sand and rock to test whether ecological divergence was also accompanied by differences in locomotor performance. Relevant physiological traits possibly associated with locomotor performance metabolic scopes and fiber type composition, power output and activity of the enzymes citrate synthase, pyruvate kinase and lactate dehydrogenase of the iliofibularis muscle - were also compared among the three Tropidurus species. We found that the two sister-species exhibited remarkable differences in jumping performance, while Tropidurus oreadicus, the more distantly related species, exhibited intermediate values. Tropidurus psamonastes, a species endemic to sand dunes, exhibited high absolute sprint speeds on sand, jumped rarely and possessed a high proportion of glycolytic fibers and low activity of citrate synthase. The sister-species Tropidurus itambere, endemic to rocky outcrops, performed a large number of jumps and achieved lower absolute sprint speed than T. psamonastes. This study provides evidence of rapid divergence of locomotor parameters between sister-species that use different substrates, which is only partially explained by variation in physiological parameters of the iliofibularis muscle.

Action of permethrin on Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) semi-engorged females: Morpho-physiological evaluation of salivary glands

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Morpho-physiological analysis of the insect fat body: A review

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Morphological and physiological responses of the recalcitrant Euterpe edulis seeds to light, temperature and gibberellins

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Empirical diversity indices applied to forest communities in different successional stages

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Comparing three indices of catch per unit effort using Bayesian geostatistics

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

PHYSIOLOGICAL and NEUROMUSCULAR PROFILE DURING A BODYPUMP SESSION: ACUTE RESPONSES DURING A HIGH-RESISTANCE TRAINING SESSION

Oliveira, AS, Greco, CC, Pereira, MP, Figueira, TR, de Araujo Ruas, VD, Goncalves, M, and Denadai, BS. Physiological and neuromuscular profile during a Bodypump session: acute responses during a high-resistance training session. J Strength Cond Res 23(2): 579-586, 2009-The main purposes of this study were 1) to describe and to compare blood lactate ([La]), heart rate (HR), and electromyographic (EMG) parameters during high-repetition training sessions (HRTSs), 2) to analyze the influence of physical fitness levels in these parameters, and, 3) to analyze the relationship between metabolic ([La]) and neuromuscular (EMG) responses during the HRTS. Fifteen healthy untrained women (21.7 +/- 2.1 years) performed an HRTS called Bodypump for 1 hour, which incorporated the use of variable free weights and high repetitions in a group setting. This session involved 10 music selections (M1-M10) containing resistive exercises for different muscle groups. After music selections 2 (M2), 4 (M4), 6 (M6), 7 (M7), and 9 (M9), [La], HR, and EMG (vastus medialis [VM], vastus lateralis [VL], iliocostalis lumborum [IC], and longissimus thoracis <) were determined. The [La] (M2, 4.00 +/- 1.45 mM; M7, 5.02 +/- 1.73 mM) and HR (M2, 153.64 +/- 18.89 bpm; M7, 16.14 +/- 20.14 bpm) obtained at M2 and M7 were similar but were significantly higher than the other moments of the session. However, EMG (root mean square [RMS]) at M2 (VL, VM, and LT) was lower than at M7. There was no significant correlation of strength and aerobic physical fitness with [La], RMS. In the same way, there was no significant correlation of [La] with RMS at M2 and M7. on the basis of our data, we can conclude that metabolic, cardiovascular, and EMG variables present different and independent behavior during an HRTS. Accordingly, for neuromuscular conditions during HRTS, it seems to be enough to induce improvement in the muscular strength of inferior limbs in untrained subjects.

Psychological, biochemical and physiological responses of Brazilian soccer players during a training program

Aims of the study. - The aim of this study is to investigate the behavior of the physiological, biochemical and psychological parameters in Brazilian soccer players during a training program.Materials. - Fifteen athletes were evaluated at the beginning (T1), in the middle (T2) and at the end (T3) of the training program. on the first day, at 7:30 am, before the blood collecting at rest for the determination of serum creatine kinase (CK), serum creatinine and serum urea, the athletes had their psychological parameters assessed by the profile of mood state questionnaire (POMS). After 90 min, they performed a 250-m sprint. on the second day at 8:30 am, the athletes had their alactic anaerobic performance measured and, after 40 min, they completed the aerobic test. Friedman test was used to verify the behavior of overtraining markers.Results. - There was a decrease in vigor score in T3 (p=0.01) compared with T1 and T2. In T3 (p=0.01), the athletes also showed an increase in serum creatinine levels compared to T1. Furthermore, in the same period, we verified a diminishing in the team performance.Conclusion. - The training program developed between T2 and T3 led to the fall of the vigor score, the increase in serum creatinine concentrations and the diminishing in team performance. (c) 2007 Elsevier Masson SAS. All rights reserved.

PHYSIOLOGICAL and PERCEIVED EXERTION RESPONSES AT INTERMITTENT CRITICAL POWER and INTERMITTENT MAXIMAL LACTATE STEADY STATE

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Fish assemblage structure and aquatic pollution in a Brazilian stream: some limitations of diversity indices and models for environmental impact studies

The aim of this study was to describe and quantify the effect of aquatic pollution on the fish assemblage structure of the Corumbatai River (Brazil), by comparing two sites with different water quality characteristics. The results revealed that abundance of individuals was low at the polluted site (B). However, the two sites did not differ significantly in species richness (total and average). This fact contradicts theories stating that portions where the transverse area of the channel is larger should present a higher biological richness. It was also observed that the ichthyofauna of site B had higher evenness, and, consequently, a tendency to a higher diversity than that at site A. This demonstrates that diversity estimates should be used cautiously in environmental impact studies, as they do not necessarily indicate better conditions of communities living in more preserved environments.