Invasive electrical impedance myography at different levels of contraction of gastrocnemius muscle of rat.

Electrical impedance myography (EIM) is as an experimental technique that associates muscle impedance with muscular activity. Changes in muscle impedance during contraction occur mainly due to changes in the morphological and physiological characteristics of muscles that lead to different impeditivities in comparison with the resting condition. There is no consensus on the details of muscular impedance during muscle activity. EIM measurements on humans are also influenced by factors such as the electrode-skin interface, layers of skin and fat, and the connective tissue that can generate undesirable effects in the impedance signal. These effects can be avoided if EIM measurements are carried out directly on the muscle by using the models of animals. This study investigates changes in the EIM signal in the gastrocnemius muscles of Wistar rats during different levels of muscular contraction. In vivo experiments were conducted on 19 male rats. The muscle was exposed, fixed on a load cell, and electrically stimulated to evoke different levels of muscle contraction. Signals of the components of impedance were analyzed against the muscular force signal. The results show moderate correlations (p < 0.05) among the impedance-related parameters of resistance (r = -0.76), reactance (r = 0.57), and phase (r = 0.53). In addition to providing an experimental protocol for the invasive collection of data on electrical impedance to minimize problems associated with surface electrodes, this study shows that of the components of impedance, resistance is most affected by the intensity of muscular contractions and that morphological changes influence impedance mainly at low intensities.

Quantitative and qualitative variables of semen from surubim do Iguaçu, Steindachneridion melanodermatum Garavello, 2005 (Siluriformes: Pimelodidae) / Variáveis quantitativas e qualitativas de sêmen de Surubim do Iguaçu Steindachneridion melanodermatum Garavello, 2005 (Siluriformes: Pimelodidae)

Abstract The objective of the present work was to assess the qualitative and quantitative characteristics of semen from the surubim do Iguaçu (Steindachneridion melanodermatum). Induced spermiation was achieved in eleven males with mean weight of 1.76 ± 0.48 kg and average age of two years and semen was collected by stripping. The average volume was 1.34 ± 0.73 mL. The duration of sperm motility was 154.4 ± 72.6 and 149.0 ± 77.5 seconds after activation with hatchery water and distilled water, respectively. The sperm concentration estimated by hemocytometer was 5.423 ± 2.155 x 1010 spermatozoa/mL. The results indicate that S. melanodermatum semen is easily obtained during the spawning season and the seminal characteristics are adequate insemination and subsequent in vitro fertilization.

Resumo O objetivo do presente trabalho foi avaliar características qualitativas e quantitativas do sêmen de surubim do Iguaçu (Steindachneridion melanodermatum). Para as análises, utilizaram-se onze machos com peso médio de 1,76±0,48 kg e idade média de dois anos, submetidos ao tratamento de hipofisação. O volume médio de sêmen coletado foi de 1,34 ± 0,73 mL. O tempo médio de motilidade dos espermatozoides após a coleta foi de 154,4 ± 72,6 e 149,0 ± 77,5 segundos para ativação com água do tanque e água destilada, respectivamente. Para a concentração espermática, a média foi de 5,423 ± 2,155 x1010 espermatozoides/mL. Os resultados indicam que o sêmen de S. melanodermatum é facilmente obtido no período reprodutivo analisado, e que as características seminais avaliadas são adequadas para reprodução induzida.

Quantitative and qualitative variables of semen from surubim do Iguaçu, Steindachneridion melanodermatum Garavello, 2005 (Siluriformes: Pimelodidae).

The objective of the present work was to assess the qualitative and quantitative characteristics of semen from the surubim do Iguaçu (Steindachneridion melanodermatum). Induced spermiation was achieved in eleven males with mean weight of 1.76 ± 0.48 kg and average age of two years and semen was collected by stripping. The average volume was 1.34 ± 0.73 mL. The duration of sperm motility was 154.4 ± 72.6 and 149.0 ± 77.5 seconds after activation with hatchery water and distilled water, respectively. The sperm concentration estimated by hemocytometer was 5.423 ± 2.155 x 1010 spermatozoa/mL. The results indicate that S. melanodermatum semen is easily obtained during the spawning season and the seminal characteristics are adequate insemination and subsequent in vitro fertilization.

Quantitative and qualitative variables of semen from surubim do Iguaçu, Steindachneridion melanodermatum Garavello, 2005 (Siluriformes: Pimelodidae) / Variáveis quantitativas e qualitativas de sêmen de Surubim do Iguaçu Steindachneridion melanodermatum Garavello, 2005 (Siluriformes: Pimelodidae)

The objective of the present work was to assess the qualitative and quantitative characteristics of semen from the surubim do Iguaçu (Steindachneridion melanodermatum). Induced spermiation was achieved in eleven males with mean weight of 1.76 ± 0.48 kg and average age of two years and semen was collected by stripping. The average volume was 1.34 ± 0.73 mL. The duration of sperm motility was 154.4 ± 72.6 and 149.0 ± 77.5 seconds after activation with hatchery water and distilled water, respectively. The sperm concentration estimated by hemocytometer was 5.423 ± 2.155 x 1010 spermatozoa/mL. The results indicate that S. melanodermatum semen is easily obtained during the spawning season and the seminal characteristics are adequate insemination and subsequent in vitro fertilization.(AU)

O objetivo do presente trabalho foi avaliar características qualitativas e quantitativas do sêmen de surubim do Iguaçu (Steindachneridion melanodermatum). Para as análises, utilizaram-se onze machos com peso médio de 1,76±0,48 kg e idade média de dois anos, submetidos ao tratamento de hipofisação. O volume médio de sêmen coletado foi de 1,34 ± 0,73 mL. O tempo médio de motilidade dos espermatozoides após a coleta foi de 154,4 ± 72,6 e 149,0 ± 77,5 segundos para ativação com água do tanque e água destilada, respectivamente. Para a concentração espermática, a média foi de 5,423 ± 2,155 x1010 espermatozoides/mL. Os resultados indicam que o sêmen de S. melanodermatum é facilmente obtido no período reprodutivo analisado, e que as características seminais avaliadas são adequadas para reprodução induzida.(AU)

Decreased serum T3 after an exercise session is independent of glucocorticoid peak.

Physical exercise increases serum glucocorticoids, which is believed to be involved in the fall of T3 after high intensity exercise. The objective was to evaluate whether a physical exercise session alters the thyroid economy and adrenal axis in humans, and the possible role of corticosteroids in thyroid function disturbance. Active but not athlete subjects were enrolled in an open field competition and cortisol, TSH, T3, and T4 were measured before and after the race. To give new insights into the mechanisms underlying the changes in thyroid economy after exercise, we used a rat model to evaluate the impact of blocking corticosterone synthesis during treadmill exercise by metyrapone administration. Cortisol levels increased 1.5-fold (from 28.2±3.8 to 42.2±2.2 µg/dl; p<0.05), while serum T3 decreased by 13% (from 115±5 to 99±5 µg/dl; p<0.05) 6 h after the race in humans. Also, in rats, glucocorticoid increased by 2-fold while T3 decreased 15% after exercise session (p<0.05). However, the complete blockage of corticosterone peak did not impair serum T3 decrease observed in rats submitted to exercise. Interestingly, the lack of corticosterone peak led not only to lower serum T3, but also to decreased serum T4, indicating that corticosterone might be fundamental for the maintenance of serum thyroid hormone levels after high intensity exercise. Although cortisol increases and T3 decreases after high intensity exercise in both humans and rats, it does not seem to be a cause-effect response since pharmacological blockage of corticosterone peak does not modulate T3 response.

Blunted response of pituitary type 1 and brown adipose tissue type 2 deiodinases to swimming training in ovariectomized rats.

Ovariectomy leads to significant increase in body weight, but the possible peripheral mechanisms involved in weight gain are still unknown. Since exercise and thyroid hormones modulate energy balance, we aimed to study the effect of swimming training on body weight gain and brown adipose tissue (BAT) type 2 iodothyronine deiodinase responses in ovariectomized (Ox) or sham-operated (Sh) rats. Rats were submitted to a period of 8-week training, 5 days per week with progressive higher duration of exercise protocol. Swimming training program did not totally prevent the higher body mass gain that follows ovariectomy in rats (16.5% decrease in body mass gain in Ox trained rats compared to 22% decrease in sham operated trained animals, in relation to the respective sedentary groups), but training of Ox animals impaired the accumulation of subcutaneous fat pads. Interestingly, swimming training upregulates pituitary type 1 (p<0.001 vs. all groups) and BAT type 2 iodothyronine deiodinases (p<0.05 vs. ShS and OxS) in sham operated but not in Ox rats, indicating an impaired pituitary and peripheral response to exercise in Ox rats. However, BAT mitochondrial O2 consumption significantly increased by swimming training in both sham and Ox groups, indicating that Ox BAT mitochondria responds normally to exercise stimulus, but does not result in a significant reduction of body weight. In conclusion, increased body mass gain produced by Ox is not completely impaired by 8 weeks of high intensity physical training, showing that these animals sustain higher rate of body mass gain independent of being submitted to higher energy expenditure.

Soluble factors from multipotent mesenchymal stromal cells have antinecrotic effect on cardiomyocytes in vitro and improve cardiac function in infarcted rat hearts.

The mechanisms underlying the functional improvement after injection of multipotent mesenchymal stromal cells (MSCs) in infarcted hearts remain incompletely understood. The aim of this study was to investigate if soluble factors secreted by MSCs promote cardioprotection. For this purpose, conditioned medium (CM) was obtained after three passages from MSC cultures submitted to 72 h of conditioning in serum-free DMEM under normoxia (NCM) or hypoxia (HCM) conditions. CM was concentrated 25-fold before use (NCM-25X, concentrated normoxia conditioned medium; HCM-25X, concentrated hypoxia conditioned medium). The in vitro cardioprotection was evaluated in neonatal ventricular cardiomyocytes by quantifying apoptosis after 24 h of serum deprivation associated with hypoxia (1% O(2)) in the absence or presence of NCM and HCM (nonconcentrated and 25-fold concentrated). The in vivo cardioprotection of HCM was tested in a model of myocardial infarction (MI) induced in Wistar male rats by permanent left coronary occlusion. Intramyocardial injection of HCM-25X (n = 14) or nonconditioned DMEM (n = 16) was performed 3 h after coronary occlusion and cardiac function was evaluated 19-21 days after medium injection. Cardiac function was evaluated by electro- and echocardiogram, left ventricular catheterization, and treadmill test. The in vitro results showed that HCM was able to decrease cardiomyocyte necrosis. The in vivo results showed that HCM-25X administered 3 h after AMI was able to promote a significant reduction (35%) in left ventricular end-diastolic pressure and improvement of cardiac contractility (15%) and relaxation (12%). These results suggest that soluble factors released in vitro by MSCs are able to promote cardioprotection in vitro and improve cardiac function in vivo.

Ultrasound biomicroscopy for biomechanical characterization of healthy and injured triceps surae of rats.

This work describes the use of ultrasound biomicroscopy (UBM) to follow up the degeneration-regeneration process after a laceration injury induced in the lateral gastrocnemius (LG) and soleus (SOL) muscles of rats. UBM (40 MHz) images were acquired and used for biomechanical characterization of muscular tissue, specifically using pennation angle (PA) and muscle thickness (MT). The animals were distributed in three groups: the variability group (VG; N=5), the gastrocnemius injured group (GG; N=6) and the soleus injured group (SG; N=5). VG rats were used to assess data variability and reliability (coefficients of variation of 9.37 and 3.97% for PA and MT, respectively). GG and SG rats were submitted to the injury protocol in the LG and SOL muscles of the right legs, respectively. UBM images of muscles of both legs were acquired at the following time points: before and after injury (immediately, 7, 14, 21 and 28 days). We observed an increase in PA for the non-injured leg 28 days after injury for both GG and SG rats (GG=10.68 to 16.53 deg and SG=9.65 to 14.06 deg; P<0.05). Additionally, MT presented a tendency to increase (GG=2.92 to 3.13 mm and SG=2.12 to 2.35 mm). Injured legs maintained pre-injury PA and MT values. It is suggested that a compensatory hypertrophic response due to the overload condition imposed to healthy leg. The results indicate that UBM allows qualitative and quantitative muscle differentiation among healthy and injured muscle at different stages after lesion.

Human umbilical cord blood cells in infarcted rats.

Therapy with bone marrow-derived cells has been used in ischemic patients with reported success. The aim of this study was to determine the therapeutic efficacy of fresh and frozen human umbilical cord blood cells (hUCB) in Wistar rats submitted to permanent occlusion of the left coronary artery. Three hours after myocardial infarction, 2 x 10(7) hUCB cells or vehicle were administered by intramyocardial injection. The animals were divided into five groups: control (N = 10), sham operated (N = 10), infarcted that received vehicle (N = 9), infarcted treated with cryopreserved hUCB (N = 7), and infarcted treated with fresh hUCB (N = 5). Cardiac function was evaluated by electrocardiogram (ECG) and echocardiogram (ECHO) before cell therapy, and by ECG, ECHO, cardiopulmonary test, and left ventricular pressure measurements 3 weeks later. After 3 weeks, both groups treated with hUCB still had Q wave present in L1, âQRS >90 degrees and reduced shortening fraction (less than 50%). In addition, cardiac indexes of left ventricular contractility and relaxation were 5484 +/- 875 and -4032 +/- 643 mmHg (cryopreserved hUCB) and 4585 +/- 955 and -2862 +/- 590 mmHg (fresh hUCB), respectively. These values were not statistically different from those of saline-treated animals. Cardiopulmonary exercise test profile was typical of infarcted hearts; exercise time was about 14 min and maximal VO2 was 24.77 +/- 5.00 mL.kg-1.min-1. These data show that hUCB therapy did not improve the cardiac function of infarcted animals or prevent cardiac remodeling.

Human umbilical cord blood cells in infarcted rats

Therapy with bone marrow-derived cells has been used in ischemic patients with reported success. The aim of this study was to determine the therapeutic efficacy of fresh and frozen human umbilical cord blood cells (hUCB) in Wistar rats submitted to permanent occlusion of the left coronary artery. Three hours after myocardial infarction, 2 x 10(7) hUCB cells or vehicle were administered by intramyocardial injection. The animals were divided into five groups: control (N = 10), sham operated (N = 10), infarcted that received vehicle (N = 9), infarcted treated with cryopreserved hUCB (N = 7), and infarcted treated with fresh hUCB (N = 5). Cardiac function was evaluated by electrocardiogram (ECG) and echocardiogram (ECHO) before cell therapy, and by ECG, ECHO, cardiopulmonary test, and left ventricular pressure measurements 3 weeks later. After 3 weeks, both groups treated with hUCB still had Q wave present in L1, âQRS >90° and reduced shortening fraction (less than 50 percent). In addition, cardiac indexes of left ventricular contractility and relaxation were 5484 ± 875 and -4032 ± 643 mmHg (cryopreserved hUCB) and 4585 ± 955 and -2862 ± 590 mmHg (fresh hUCB), respectively. These values were not statistically different from those of saline-treated animals. Cardiopulmonary exercise test profile was typical of infarcted hearts; exercise time was about 14 min and maximal VO2 was 24.77 ± 5.00 mL·kg-1·min-1. These data show that hUCB therapy did not improve the cardiac function of infarcted animals or prevent cardiac remodeling.

Inhibition of brain renin-angiotensin system improves diastolic cardiac function following myocardial infarction in rats.

1. Recently, we demonstrated that oral captopril treatment improved diastolic function and attenuated cardiac remodelling after myocardial infarction (MI) in rats. Considering the feasible role of the brain renin-angiotensin system (RAS) in heart failure, in the present study we investigated the role of the captopril injected intracerebroventricularly (i.c.v.) on the progression of cardiac dysfunction. 2. Male Wistar rats underwent experimental MI or sham operation. Infarcted animals received daily i.c.v. injections of captopril (approximately 200 mg/kg; MI + Cap) or saline (MI) from 11 to 18 days after infarction. Electro- and echocardiogram assessments were performed before and after i.c.v. treatment (10 and 18 days after MI, respectively). Water and hypertonic saline ingestion were determined daily between 12 and 16 days after MI. 3. Electrocardiograms from the MI and MI + Cap groups showed signs that resembled large MI before and after i.c.v. treatment. However, despite similar systolic dysfunction observed in both groups, only captopril-treated rats exhibited reduced left ventricular (LV) dilatation and improved LV filling, as assessed by echocardiograms, and low levels of water ingestion compared with the saline-treated control group. 4. The results of the present study suggest that the brain RAS may participate in the development of cardiac dysfunction induced by ischaemia and that inhibition of the brain RAS may provide a new strategy for the prevention of diastolic dysfunction.

High-intensity ultraendurance promotes early release of muscle injury markers.

OBJECTIVE: To evaluate the impact of high-intensity ultraendurance (HIU) cycling, using it as a possible way to understand muscle injury kinetics and blood immune cells' release during high-intensity prolonged exercise DESIGN: Male amateur triathletes enrolled during a cycling race of the International Bike Championship 800 km cycling relay (approximately 23 h). Each athlete alternately cycled 20-25 minutes until exhaustion and performed a total of approximately 200 km. RESULTS: Creatine kinase levels in blood reached a 300% rise in a sigmoidal pattern, while lactate dehydrogenase levels increased by 30-40% following a hyperbolic pattern. Aspartate aminotransferase and alanine aminotransferase levels increased by up to 250% and 140%, respectively. Liver injury markers such as alkaline phosphatase and gamma-glutamyltransferase remained stable. Platelets increased by 20-30% from pre-exercise, and there was no change in haematocrit during the race. White blood cells rose by nearly 200%. Leucocytes rose 210% during the race, with a major component coming from neutrophils, which increased more than 300%. Triacylglycerol levels were decreased at the finish and total cholesterol levels remained unchanged. Urate increased (by up to 35%) during the first half of the race, and urea levels increased with a different pattern, increasing by 45% in the second half. CONCLUSIONS: This study showed the blood appearance kinetics of muscle injury markers and some metabolites. It is suggested that the increase in these enzymes came primarily from muscle damage, rather than liver damage, and that white blood cells are selectively mobilised independently of haemoconcentration. The early appearance of muscle injury markers in this kind of exercise was also shown.

Glutamine protects against increases in blood ammonia in football players in an exercise intensity-dependent way.

OBJECTIVE: High-intensity and prolonged exercise significantly enhances the levels of plasma ammonia, a metabolite with toxic effects on the central nervous system. The main purpose of the present study was to evaluate the metabolic response of athletes to glutamine (Gln) and alanine (Ala) supplementation, since these amino acids have a significant influence on both anaplerosis and gluconeogenesis. METHODS: Professional football players were assigned to groups receiving either Gln or Ala supplementation (100 mg kg(-1) body weight); this supplementation was either short-term or long-term and was given immediately before exercise. The players were evaluated using two exercise protocols, one with intervals (n = 18) and the other with continuous intensity (n = 12). RESULTS: Both types of exercises increased ammonia, urate, urea and creatinine in blood. Chronic Gln supplementation partially protected against hyperammonemia after a football match (intermittent exercise: Gln -140 (SEM 13)% vs Ala -240 (SEM 37)%) and after continuous exercise at 80% of the maximum heart rate (Gln -481 (SEM 44)% vs placebo -778 (SEM 99)%). Urate increased by 10-20% in all groups, independently of supplementation. Glutamine once a day supplementation induced a greater elevation in urate as compared to alanine at the end of the game; however, long-term supplementation provoked a lesser increment in urate. Exercise induced similar increases in creatinine as compared to their respective controls in either acute or chronic glutamine administration. CONCLUSIONS: Taken together, the results suggest that chronically supplemented Gln protects against exercise-induced hyperammonemia depending on exercise intensity and supplementation duration.

Cardiac effects of oxytocin: is there a role for this peptide in cardiovascular homeostasis?

Oxytocin is well known for its role in reproduction. However, evidence has emerged suggesting a role in cardiovascular and hydroelectrolytic homeostasis. Although its renal effects have been characterized, the cardiac ones have not been much studied. Therefore, we aimed to investigate the cardiac effects of oxytocin both in vivo and in vitro. In unanesthetized rats (n=6) intravenous oxytocin (1 mug) decreased dP/dt(max) by 15% (P<0.05) and heart rate by 20% (P<0.001), at the first minute after injection. dP/dt(max) was still lower in OT-treated rats than in controls (n=8) after 15 min (P<0.05), while heart rate returned to control values after 5 min. In isolated hearts, oxytocin was able to promote negative inotropic and chronotropic effects. Perfusion with 10(-5), 10(-6) and 10(-7)M oxytocin resulted in approximately 60% (P<0.01), 25% (P<0.01) and 10% (P<0.05) reduction of left ventricle developed pressure, without effect in lower concentrations (10(-10) to 10(-8) M). Also, dP/dt(max) was reduced by 45 and 20% (10(-5) e 10(-6) M; P<0.01), while diastolic pressure raised and heart rate fell only with 10(-5)M oxytocin (P<0.05). Intravenous oxytocin (1 mug; n=6) increased arterial pressure by 22% at the first minute (+23+/-3 mm Hg; P<0.001), returning to control value thereafter. Thus, oxytocin is able to promote directly negative inotropic and chronotropic effects, but its in vivo effect also involves a reflex mechanism, originated from its pressor effect.

Effects of long-term continuous exposure to light on memory and anxiety in mice.

The studies on the relationship between the light/dark cycle and memory function mostly used protocols of acute disruption of the circadian rhythm. The aim of the present study is to verify the effects of long-term continuous exposure to light on memory, anxiety and motor parameters of mice tested in the plus-maze discriminative avoidance task. Mice were conditioned to choose between the two enclosed arms (one aversive and one non-aversive) while avoiding the open arms of a modified elevated plus-maze apparatus. Memory was evaluated by the time spent in the aversive enclosed arm, anxiety was evaluated by the time spent in the open arms and locomotor behavior was evaluated by number of entries in the arms of the maze. The results showed that long-term (35-42 days) continuous light exposure did not modify memory or anxiety parameters but increased locomotor activity. While the increase in locomotor behavior is in line with previous studies, the unexpected absence of alterations in memory and anxiety (reported to be influenced by the circadian rhythm) is discussed.

Evaluation of the courtship and of the hybrid male sterility among Drosophila buzzatii cluster species (Diptera, Drosophilidae)

In the Drosophila repleta group the establishment of subgroups and complexes made on the basis of morphological and cytological evidences is supported by tests of reproductive isolation. Among species in the repleta group, the buzzatii cluster, due to its polymorphism and polytipism, is an excellent material for ecological and speciation studies. Some interspecific crosses involving Drosophila seriema, Drosophila sp. B, D. koepferae and D. buzzatii strains were completely sterile while others involving strains from these species produced F1 hybrids that did not yield F2. In the present work, data on courtship duration and copula occurrence obtained in the analysis of flies from parental sterile crosses and on spermatozoon mobility observed in F1 hybrids that did not yield F2 are presented. Copula did not occur during one hour of observation and the spermatozoon also did not show mobility at any of the analyzed stages (3, 7, 9 and 10 days old). There was a high variation in courtship average duration and in the percentage of males that courted the females. The reproductive isolation mechanisms indicated by these observations were pre and post-zygotic, as supported by the absence of copula and male sterility. Data obtained also showed the occurrence of different degrees of reproductive compatibility among the strains classified as the same species but from distinct geographic localities

Intramedullary nailing of humeral shaft fractures.

From 1996 until 2000 we treated 52 humeral shaft fractures with AO unreamed nailing. Mean patient age was 35.8 years and the average follow-up 29.6 months. There were 31 type A fractures, 15 type B, and 6 type C. Closed retrograde nailing was performed in 46 cases and open nailing in six. Functional results were excellent in 48 cases, moderate in three, and poor in one.

Ecografía realizada por cirujanos en el manejo de pacientes con trauma / Echography performed by surgeons in the management of patients with trauma

BACKGROUND: Ultrasonography is useful in trauma patients to detect pleural effusions or peritoneal fluid. AIM: To assess the value of ultrasonography performed by surgeons in the assessment of trauma patients. MATERIAL AND METHODS: A retrospective review of ultrasonography reports and clinical history of 284 trauma patients. RESULTS: One hundred fifty six patients had blunt trauma and 128 had penetrating trauma. Ultrasonography detected peritoneal fluid in 20 per cent, pericardial effusion in 1 per cent and pleural effusion in 1 per cent. Eight percent had visceral damage or hematomas, without peritoneal fluid. None of the patients with a normal ultrasonography required surgery for hemoperitoneum; however, four patients had intestinal perforations and required surgery. CONCLUSIONS: Ultrasonography had a 100 per cent sensitivity and specificity for the detection of clinically significant hemoperitoneum. Emergency ultrasonography performed by surgeons is useful and accurate.

Evaluation of the courtship and of the hybrid male sterility among Drosophila buzzatii cluster species (Diptera, Drosophilidae).

In the Drosophila repleta group the establishment of subgroups and complexes made on the basis of morphological and cytological evidences is supported by tests of reproductive isolation. Among species in the repleta group, the buzzatii cluster, due to its polymorphism and polytipism, is an excellent material for ecological and speciation studies. Some interspecific crosses involving Drosophila seriema, Drosophila sp. B, D. koepferae and D. buzzatii strains were completely sterile while others involving strains from these species produced F1 hybrids that did not yield F2. In the present work, data on courtship duration and copula occurrence obtained in the analysis of flies from parental sterile crosses and on spermatozoon mobility observed in F1 hybrids that did not yield F2 are presented. Copula did not occur during one hour of observation and the spermatozoon also did not show mobility at any of the analyzed stages (3, 7, 9 and 10 days old). There was a high variation in courtship average duration and in the percentage of males that courted the females. The reproductive isolation mechanisms indicated by these observations were pre and post-zygotic, as supported by the absence of copula and male sterility. Data obtained also showed the occurrence of different degrees of reproductive compatibility among the strains classified as the same species but from distinct geographic localities.