Differences in the isodesmin pattern between the electric organs of Electrophorus electricus L.

Desmin, the intermediate filament protein of muscle, is present in the electric organs of Electrophorus electricus L. as five isovariants, instead of the one to two isovariants found in muscle. We analyzed the isodesmin pattern in the three different electric organs using densitometry of Coomassie blue-stained bands in electrofocusing polyacrylamide gel electrophoresis. We were able to compare the relative amount of each of the five desmin isovariants in an isodesmin pattern characteristic of each electric organ. These patterns proved to be, in some cases, statistically different. Desmin in each electric organ could have slightly different functions in order to correlate with the organ-specific isovariant patterns.     

Morphological and physiological differences of the auditory system in three related bushcrickets (Orthoptera: Phaneropteridae, Poecilimon)

Abstract. The auditory system of three closely related bushcrickets was investigated with respect to morphological and physiological differences. The size of the acoustic vesicle in the prothorax cavity and the size of the acoustic spiracle were compared to differences in auditory tuning of the tympanic nerve and differences in the directionality. The results indicate that a small auditory vesicle and auditory spiracle provide reduced sensitivity in the high frequency range (above 10—15 kHz), but increase sensitivity at low frequencies (below 10 kHz). The directionality of the hearing system deteriorates at frequencies between 10 and 25 kHz in species with a small spiracle and trachea. The evolutionary implications of these differences of the auditory systems are discussed. They are considered to be influenced more by ecological factors than bioacoustical ones.     

Functional innovation through vestigialization in a modular marine invertebrate

Few studies show how morphological vestigialization may facilitate functional innovation. Fewer still describe the co‐occurrence of the derived and more ancestral structures in the same genetic individual. In the present study, we explore that rare instance in a modular (colonial) marine invertebrate. Using laser scanning confocal microscopy with fluorescent staining and behavioural observations, we describe homologous structures in polymorphic modules (zooids) in the bryozoan Bugula flabellata and document the occurrence of previously unreported retractor and circular muscles in the more derived module, the bird's‐head avicularium. In the evolution of a sessile feeding zooid to a moveable nonfeeding zooid with sensory and grasping functions, transformations were effected in the food‐capture apparatus, orificial structures, musculature, and sensory structures. We expand on and clarify previous reports of homologies between ancestral and derived modules in bryozoans and argue that vestigialization and augmentation of homologous structures were coincident with functional innovations in the avicularium. The present study offers rare evidence for the evolution of functional innovation through vestigialization. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104 , 63–74.     

Effects of exposure to imidacloprid contaminated feed on the visceral organs of adult male rabbits (Oryctolagus cuniculus)

The best-known and often used systemic, broad-spectrum neonicotinoid pesticide is imidacloprid (IMI). This study was carried out on adult male rabbits (n = 12) to assess the residual effects of exposure to IMI-contaminated diet on the liver, lung, heart, and kidney. Pesticide-exposed rabbits (n = 6) received IMI contaminated green grass (Bildor® 0.5 ml (100 mg)/L water) every alternative day once daily for up to 15 days. The remaining rabbits were fed a standard diet free of pesticides as a control. During routine monitoring of the rabbits throughout the experiment, there were no apparent toxic symptoms identified. On days 16, after deep anesthesia blood and visceral organs were collected. The levels of hepatic serum aspartate transaminase and alanine transaminase were considerably elevated in IMI-exposed rabbits (p ≤ 0.05). Thin layer chromatography revealed that the residue of IMI was at the detectable level in the liver and stomach. Histopathologically, the liver revealed coagulation necrosis with granulomatous inflammation and congestion in portal areas with dilated and congested central veins. The lungs showed congestion of blood vessels and granulomatous inflammation around the terminal bronchiole. Accumulations of inflammatory cells were observed in the cortico-medullary junction in the kidney. The heart showed necrosis and infiltration of mononuclear cells within the cardiac muscles. The findings of the current study emphasize that IMI-contaminated feed exposure causes toxicity into the cellular level of different visceral organs of adult male rabbits and it may also cause the similar toxic effects of the other mammals specially the occupationally exposed persons.     

Ultrastructural demonstration of the model of Litopenaeus vannamei (Crustacea,Penaeidae) male sexual maturation and spermatozoal capacitation

The present study demonstrates ultrastructurally the model of Litopenaeus vannamei male sexual maturation and spermatozoal capacitation. The results show that phase 1 of the model occurred in the seminiferous tubules and includes spermatogenesis. In this phase, throughout differentiation of spermatogonia into late spermatids the following processes were observed: (1) decondensation of chromatin; (2) rupture of the nuclear envelope; (3) reduction of the cytoplasm and degeneration of organelles; (4) formation of the acrosome via fusion of cytoplasmic vesicles. Phase 2 comprised of spermatozoal maturation, a process that started with the transfer of late spermatids into the seminiferous ducts and ended with the formation of the acrosomal spike in the terminal ampoules. During this phase, development of the subacrosomal region and lateral electron-dense particles occurred in the seminiferous ducts, which is a novel finding of this species. Phase 3 was observed after spermatophore placement on the female thelycum and was mainly characterized by ultrastructural changes in the nucleus and the subacrosomal region. These results are in agreement with the model of male sexual maturation and spermatozoal capacitation proposed for L. vannamei.     

Nitrogen redistribution during grain growth in wheat (Triticum aestivum L.)

The activity of a range of endo- and exopeptidase enzymes have been measured in the glumes, flag leaf and stem during the period of grain development in wheat. The enzymes show a sequential pattern of appearance with activity peaks occurring at a number of intervals from anthesis until just prior to the cessation of grain growth. Of the enzymes studied only the haemoglobin- and casein-degrading activity and alanylglycine-dipeptidase activity increased during the period of rapid protein loss, while aminopeptidase, carboxypeptidase and leucyltyrosine dipeptidase reached maximum activity prior to this period.     

Theophrastus on geophytes

NEGBI, M., 1989. Theophrastus on geophytes . The nature of the geophilous organs of the geophytes described by Theophrastus (371-287 B.C.) in Historia Planiarum and De Causis Planlarum is presented and discussed. Most of the geophytes and the hydrogeophytes mentioned in these books (excluding species of Allium , biennial vegetables, and a few others) are critically reviewed. Certain lost agricultural practices mentioned by Theophrastus are strengthened and made explicable by comparisons from Pliny's Natural History , and Hebrew literature of the first centuries A.D.: Mishnah and Talmud. Theophrastus's interest in plants is shown to be of a pure nature although most of his examples are cultivated or otherwise useful plants. The possible sources of his knowledge of Egyptian plants are discussed.     

From humoral fever to neuroimmunological control of fever

Fever is a part of the acute phase response to infection or systemic inflammation. It is thus a part of a complex physiological defence strategy against micro-organisms invading the body of the host, or against non-microbial agents recognized as foreign by mobile immune cells of the body. The fever is induced by inflammatory mediators (prostaglandins, cytokines) released by immune cells activated by contacts with foreign molecules (exogenous pyrogens). These fever-inducing mediators, produced by the host cells (endogenous pyrogens), were originally thought to be distributed by means of the bloodstream (similarly to hormones) to different tissues of the body. Although the details of their transport across the blood–brain-barrier have not been clarified, it has been assumed that they activate the local production of inflammatory mediators within the brain, inducing a change in the thermoregulatory set-range and resulting in fever (humoral theory of fever). This concept has apparently changed in the past few years. Evidence has recently been presented supporting the possibility of the transport of immune signals to the brain via vegetative and peripheral nerves. In this review an attempt is made to describe the events leading to a fever response accompanying the systemic inflammation against a background of microbiological, immunological and physiological data. The experimental evidence published during the last five years has been reviewed, and a new concept of neuroimmunological control of fever is presented. This concept suggests that the host immune defence is coordinated through an integration of the neural, immune, hemopoietic and endocrine systems. The brain seems to be informed of any damage or antigenic challenge in the periphery of the body by a sensory host-monitoring system, and this information is confirmed by immune signals delivered by the humoral transport. The combination of these signals would allow the brain to recognize the nature of the challenge, and to activate an appropriate defence strategy. Fever as a part of many successful defence strategies against infections may thus be beneficial.