Development and silk production by silkworm larvae after topical application of methoprene

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

Silk formation mechanisms in the larval salivary glands of Apis mellifera (Hymenoptera : Apidae)

The mechanism of silk formation in Apis mellifera salivary glands, during the 5th instar, was studied. Larval salivary glands were dissected and prepared for light and polarized light microscopy, as well as for scanning and transmission electron microscopy. The results showed that silk formation starts at the middle of the 5th instar and finishes at the end of the same instar. This process begins in the distal secretory portion of the gland, going towards the proximal secretory portion; and from the periphery to the center of the gland lumen. The silk proteins are released from the secretory cells as a homogeneous substance that polymerizes in the lumen to form compact birefringent tactoids. Secondly, the water absorption from the lumen secretion, carried out by secretory and duct cells, promotes aggregation of the tactoids that form a spiral-shape filament with a zigzag pattern. This pattern is also the results of the silk compression in the gland lumen and represents a high concentration of macromolecularly well-oriented silk proteins.

Efeito de diferentes intervalos de recuperação entre as séries sobre o desempenho muscular no exercício leg-press em idosas não treinadas

OBJETIVO: Verificar a influência de dois diferentes intervalos de recuperação (IR) entre as séries no exercício leg-press sobre o número e sustentabilidade das repetições e no volume total, em idosas não treinadas. MÉTODOS: Onze idosas (66,5 ± 5,0 anos; 59,2 ± 9,1kg; 146,4 ± 34,9cm) foram submetidas a duas sessões experimentais de exercícios com pesos com intensidade de 15 repetições máximas. Cada sessão experimental foi composta por três séries realizadas até a fadiga muscular utilizando IR de um (IR-1) ou três minutos (IR-3). As sessões experimentais foram separadas por, no mínimo, 48 horas. Todas as participantes realizaram ambos os protocolos e um delineamento cross-over balanceado foi utilizado para determinar a ordem das sessões experimentais. RESULTADOS: Para ambos os IR entre as séries, reduções significativas (P < 0,05) no número e na sustentabilidade das repetições foram observadas da primeira para a segunda e terceira séries e da segunda para a terceira séries. Diferenças significativas (P < 0,05) entre os IR foram observadas nas duas séries finais. O volume total da sessão realizada com IR-3 foi estatisticamente superior (20,4%; P < 0,05) quando comparada a sessão IR-1. CONCLUSÃO: O número e a sustentabilidade das repetições e o volume total de treino de idosas não treinadas são influenciados pelo IR empregado entre as séries. Maiores IR devem ser utilizados quando a finalidade for otimizar o volume de treino por meio da sustentabilidade das repetições. Em contrapartida, menores IR devem ser utilizados quando a meta for obter maiores níveis de fadiga muscular.

Ultrastructure of the excretory duct in the silk gland of the sugarcane borer Diatraea saccharalis (Lepidoptera : Pyralidae)

The excretory duct in the silk gland of the sugarcane borer Diatraea saccharalis consists of two morphologically distinct regions, recognized by scanning and transmission electron microscopy. The thin posterior region, adjacent to the glandular region, presents a regular surface. Secretory vesicles containing either electron-dense or fibrillar cuticular-like materials are observed in their apical cytoplasm; the same cuticular materials were detected as extracellular deposits among the microvilli. The short anterior region, near the common duct, exhibits surface protrusions; there are no secretory vesicles in their apical cytoplasm. These results show that only the duct cells at the posterior region are involved in the secretion of the cuticular intima elements. Desmosome-like structures were visualized linking together adjacent microvillar membranes only in the cells of anterior duct region, with unknown function. The transition between the duct and the glandular region is abrupt; the cells of the glandular and posterior duct regions present large amounts of microtubules. Nerve fibers can be observed between the duct cells in their two regions, suggesting that control of silk secretion may occur in the excretory duct via neurotransmitter liberation. (C) 2002 Elsevier B.V. Ltd. All rights reserved.

Efficient Distributed Feedback Dye Laser in Silk Fibroin Films

We observed longitudinal single-mode operation in a distributed feedback dye laser consisting of silk fibroin films doped with Rhodamine 6G dye and infiltrated with silica or silver nanoparticles.

Politics, press and military participation in the abdication of d. Pedro I

This work seeks to contribute to a better understanding of the Abdication, analyzing how and why sections of the army joined the liberal groups against the emperor, focusing on the period that immediately preceded this event. The argument is that the alliance between sections of the army and the liberal groups in 1831 was possible because the expansion of the "public space" in the city of Rio de Janeiro, a process in which newspapers such as "O Republico" played a key role as they became a privileged locus for political disputes. The article shows that that newspaper helped to build a political identity based on the defense of Brazilian interests against Portuguese despotism, giving momentum to internal conflicts around this subject that were already taking place among sections of the army and hence triggering the process that would lead to the Abdication.

Electromyographic evaluation of the rectus femoris muscle during exercises performed on the leg press

The rectus femoris was analysed in 10 volunteers during knee flexion and extension with the feet in normal, plantar flexion and dorsal flexion positions. Hewlett-Packard surface electrodes, an electromyographic signal amplifier, a computer equipped with an A/D conversion plaque (Model CAD 10/26), software specially designed to record and analyse the signals, Horizontal Leg Press, and electrogoniometers were used. The rectus femoris muscle showed strong potentials at the beginning of knee extension. In the simultaneous bendings of the knee and hip the activity was strong toward the end of the movement. The rectus femoris showed a similar activity both in the upper and lower platforms. As for foot positions, the rectus femoris showed the smallest potentials with the foot in plantar flexion and the largest ones with the foot in dorsal flexion.

Electromyographic behaviour of the gastrocnemius muscle during knee extension and flexion performed on the leg press

The gastrocnemius was analysed in 10 male volunteers during knee flexion and extension with the foot in normal, plantar flexion and dorsal flexion positions. Hewlett-Packard surface electrodes, an electromyographic signal amplifier, a computer equipped with an AID conversion plaque (Model CAD 10/26), a software specially designed to record and analyse the signals, a horizontal leg press, and electrogoniometers were used. The gastrocnemius muscle showed strong potentials at the end of knee extension and beginning of knee flexion. The muscle presented a similar activity both in the zipper and lower platforms. As to bilateral action, the right gastrocnemius presented stronger potentials on the upper platforms, whereas the potentials were bilaterally similar on the lower platforms. As for foot position, the gastrocnemius presented strong potentials when the foot was in plantar flexion. The remaining positions had no effect on the work of the muscle.

Electromyographic validation of the trapezius and serratus anterior muscles in military press exercises with open grip.

It was studied the trapezius muscle and serratus anterior muscle in 24 male volunteers using a 2-channel TECA TE 4 electromyograph and Hewlett Packard surface electrodes, during the execution of four different modalities of military press exercises with open grip. The results showed that TS acted significantly in the modalities standing and sitting press behind neck, while SI acted in all the modalities, i.e., standing and sitting press behind neck and forward, justifying their inclusion as basic exercises for physical conditioning programmes.

Electromyographic validation of the trapezius and serratus anterior muscles in military press exercises with open and middle grip

Electromyographic activity of the trapezius muscle and serratus anterior muscle was analysed in 4 different modalities of military press exercises, each of them with 2 grips: open and middle. It was analyzed 24 male volunteers using a 2-channel TECA TE 4 electromyograph and Hewlett Packard surface electrodes. The TS and SI muscles acted with high and very high activity in all the modalities of military press exercises. Statistically, they did not show significative difference in the performance of the exercises with open and middle grip, justifying the inclusion of this group of exercises with both grips for the physical conditioning programmes.

Electromyographic validation of the trapezius and serratus anterior muscles in military press exercises with middle grip

Electromyographic activity of the trapezius muscle and serratus anterior muscle was analysed in 24 male volunteers using a 2-channel TECA TE 4 electromyograp, during the execution of four different modalities of military press exercises with middle grip. The trapezius acted preferentially in the modalities standing press behind neck; and sitting forward and press behind neck, while SI did not show any significative difference among the modalities. The high levels of action potentials with which TS and SI acted justify the inclusion of these exercises in physical programmes.

Macromolecular array patterns of silk gland secretion in social Hymenoptera larvae

The cocoon, produced by most holometabolous insects, is built with silk that is usually produced by the larval salivary gland. Although this silk has been widely studied in the Lepidoptera, its composition and macromolecular arrangement remains unknown in the Hymenoptera. The macromolecular array patterns of the silk in the larval salivary gland of some meliponids, wasps, and ants were analyzed with polarized-light microscopy, and they were compared with those of Bombyx mori (Lepidoptera). There is a birefringent secretion in the glandular lumen of all larvae, due to filamentous structural proteins that display anisotropy. The silk in the distal, middle and proximal regions of the secretory portion of Formicidae and Vespidae glands presented a lattice optical pattern. We found a different pattern in the middle secretory portion of the Meliponini, with a zigzag rather than a lattice pattern. This indicates that the biopolymer fibers begin their macromolecular reorganization at this glandular region, different from the Formicidae and the Vespidae, in which the zigzag optical pattern was only found at the lateral duct. Probably, the mechanism of silk production in the Hymenoptera is a characteristic inherited from a common ancestor of Vespoidea and Sphecoidea; the alterations in the pattern observed in the Meliponini could be a derived characteristic in the Hymenoptera. We found no similarity in the macromolecular reorganization patterns of the silk between the Hymenoptera species and the silkworm.

Histochemical and ultrastructural evidence of lipid secretion by the silk gland of the sugarcane borer Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae)

The silk gland in Lepidoptera larvae is responsible for the silk production used for shelter or cocoon construction. The secretion of fibroin and sericin by the different silk gland regions are well established. There are few attempts to detect lipid components in the insect silk secretion, although the presence of such element may contribute to the resistance of the shelter to wet environment. This study characterizes the glandular region and detects the presence of lipid components in the secretion of the silk gland of Diatraea saccharalis (Fabricius). The silk gland was submitted to histochemical procedure for lipid detection or conventionally prepared for ultrastructural analyses. Lipid droplets were histochemically detected in both the apical cytoplasm of cell of the anterior region and in the lumen among the microvilli. Ultrastructural analyses of the anterior region showed lipid material, visualized as myelin-like structures within the vesicular Golgi complex and in the apical secretory globules, mixed up with the sericin; similar material was observed into the lumen, adjacent to the microvilli. Lipids were not detected in the cells neither in the lumen of the posterior region. Our results suggest that the silk produced by D. saccharalis has a minor lipid content that is secreted by the anterior region together with the sericin.

Electromyographic validation of the muscles deltoid (anterior portion) and pectoralis major (clavicular portion) in military press exercises with open grip

It was analized the deltoid muscle anterior portion and the pectoralis major clavicular portion in 24 male volunteers using a two-channel electromyograph TECA TE 4, and Hewllet Packard surface electrodes, in 4 modalities of military press exercises with open grip. The results showed high inactivity for PMC in almost all the modalities while DA developed very high levels of action potentials in all the modalities assessed.