The expression of a hunchback ortholog in the polychaete annelid Platynereis dumerilii suggests an ancestral role in mesoderm development and neurogenesis

Orthologs of the Drosophila gap gene hunchback have been isolated so far only in protostomes. Phylogenetic analysis of recently available genomic data allowed us to confirm that hunchback genes are widely found in protostomes (both lophotrochozoans and ecdysozoans). In contrast, no unequivocal hunchback gene can be found in the genomes of deuterostomes and non-bilaterians. We cloned hunchback in the marine polychaete annelid Platynereis dumerilii and analysed its expression during development. In this species, hunchback displays an expression pattern indicative of a role in mesoderm formation and neurogenesis, and similar to the expression found for hunchback genes in arthropods. These data suggest altogether that these functions are ancestral to protostomes.Pierre Kerner and Fabiola Zelada González contributed equally to this work.     

Phylogenetic analysis of the thiolase family. Implications for the evolutionary origin of peroxisomes

Summary The thiolase family is a widespread group of proteins present in prokaryotes and three cellular compartments of eukaryotes. This fact makes this family interesting in order to study the evolutionary process of eukaryotes. Using the sequence of peroxisomal thiolase from Saccharomyces cerevisiae recently obtained by us and the other known thiolase sequences, a phylogenetic analysis has been carried out. It shows that all these proteins derived from a primitive enzyme, present in the common ancestor of eubacteria and eukaryotes, which evolved into different specialized thiolases confined to various cell compartments. The evolutionary tree obtained is compatible with the endosymbiotic theory for the origin of peroxisomes. Offprint requests to: J.E. Pérez-Ortín     

Noradrenergic and adrenergic systems in the brain of the urodele amphibian,Pleurodeles waltlii,as revealed by immunohistochemical methods

The distribution of noradrenaline and adrenaline in the brain of the urodele amphibian Pleurodeles waltlii has been studied with antibodies raised against noradrenaline and the enzymes dopamine--hydroxylase and phenylethanolamine-N-methyltransferase. Noradrenaline-containing cell bodies were found in the anterior preoptic area, the hypothalamic nucleus of the periventricular organ, the locus coeruleus and in the solitary tract/area postrema complex at the level of the obex. Noradrenergic fibers are widely distributed throughout the brain innervating particularly the ventrolateral forebrain, the medial amygdala, the lateral part of the posterior tubercle, the parabrachial region and the ventrolateral rhombencephalic tegmentum. Putative adrenergic cell bodies were found immediately rostral to the obex, ventral to the solitary tract. Whereas the cell bodies and their dendrites were Golgi-like stained, axons were more difficult to trace. Nevertheless, some weakly immunoreactive fibers could be traced to the basal forebrain. A comparison of these results with data previously obtained in anurans reveals not only several general features, but also some remarkable species differences.Abbreviations Acc Nucleus accumbens - AP area postrema - Apl amygdala, pars lateralis - Apm amygdala, pars medialis - ca commissura anterior - Cb cerebellum - cc central canal - Dp dorsal pallium - epl external plexiform layer - gl glomerular layer of the olfactory bulb - H ganglion habenulae - igl internal granular layer - Ip nucleus interpeduncularis - Lc locus coeruleus - Ll lateral line lobe - Lp lateral pallium - Ls lateral septum - ml mitral cell layer - Mp medial pallium - Ms medial septum - nPT nucleus pretectalis - NPv nucleus of the periventricular organ - nV nervus trigeminus - oc optic chiasm - Poa preoptic area - Ri nucleus reticularis inferior - SC nucleus suprachiasmaticus - sol solitary tract - Str striatum - thd thalamus dorsalis - thv thalamus ventralis - To tectum opticum - TP tuberculum posterius - V ventricle - VH ventral hypothalamic nucleus - III nucleus nervi oculomotorii - IXm nucleus motorius nervi glossopharyngei - Xm nucleus motorius nervi vagi     

The posibility of soil micromycetes produced the abscisic acid

The typical soil micromycetes Aspergillus niger and Cladosporium cladosporioides from the family moniliaceae were investigated with emphasis on production of ABA into the culture medium. The both fungi were cultivated in a static liquid Czapek — Dox medium and agar Czapek — Dox medium. Aspergillus niger and Cladosporium cladosporioides showed ability to produce ABA. Analytical detection of ABA from the culture medium was performed by TLC combinated with biotest and HPLC with spectroscopy.     

Tight Junctions and the Experimental Modifications of Lipid Content

Tight junctions (TJs) are cell-to-cell contacts made of strands, which appear as ridges on P faces and complementary furrows on E faces on freeze fracture replicas. Evidences and opinions on whether these strands are composed of either membrane-bound proteins or lipid micelles are somewhat varied. In the present work we alter the lipid composition of Madin-Darby canine kidney monolayers using a novel approach, while studying (i) their transepithelial electrical resistance, a parameter that depends on the degree of sealing of the TJs; (ii) the apical-to-basolateral flux of 4 kD fluorescent dextran (J_DEX), that reflects the permeability of the intercellular spaces; (iii) the ability of TJs to restrict apical-to-basolateral diffusion of membrane lipids; and (iv) the pattern of distribution of endogenous and transfected occludin, the sole membrane protein presently known to form part of the TJs. We show that changing the total composition of phospholipids, sphingolipids, cholesterol and the content of fatty acids, does not alter TER nor the structure of the strands. Interestingly, enrichment with linoleic acid increases the J_DEX by 631%. The fact that this increase is not reflected in a decrease of TER, suggests that junctional strands do not act as simple resistive elements but may contain mobile translocating mechanisms. Received: 7 November 1997/Revised: 20 March 1998     

In vitro insect-feeding bioassay to determine the resistance of transgenic rice plants transformed with insect resistance genes against striped stem borer (Chilo suppressalis)

Summary To determine the degree of insect resistance in transgenic plants, different bioassays are used which typically use either whole plant or small pieces of leaves or stems of transgenic plants, following culture under greenhouse conditions. An in vitro insect-feeding bioassay is presented which permits the infestation of transgenic plantlets with newly hatched larvae from the striped stem borer. The bioassay consists of the germination of rice seeds in vitro using Murashige and Skoog medium in test tubes, and then infestation of each 3–4 cm long seedling with one neonate larva obtained from surfacesterilized eggs of Chilo suppressalis. The infested in vitro plantlets are kept in culture rooms at 25°C for several days and then the seedling damage and the growth of the larvae are analyzed. Senia (japonica variety) homozygous transgenic rice plants were used for these experiments. The plants were transformed with either the cry1B or the maize proteinase inhibitor (mpi) genes. Both genes confer resistance to Chilo suppressalis. With non-transformed plants the larvae grew and developed normally, feeding on the small rice plantlets. In contrast, with cry1B plants, the neonate larvae died during the first days of the infestation. These plantlets recovered completely and developed similarly to the non-infested control plants. With transgenic plants transformed with the mpi gene, the neonate larvae did not die but grew more slowly compared with the controls. Thus, this in vitro insect-feeding bioassay is a rapid and easy method to detect the resistance of cry and mpi transgenic plants to stem borers such as Chilo suppressalis.     

Effects of protein deficiency on liver trace elements and antioxidant activity in carbon tetrachloride-induced liver cirrhosis

In liver cirrhosis, liver tissue becomes progressively substituted by fibrosis, ultimately leading to architectural distortion, liver circulatory changes, and liver failure. Some data support the hypothesis that protein undernutrition may play a role in the development and progression of nonalcoholic liver cirrhosis and that this progression is at least partially mediated by changes in glutathione peroxidase (GPX), superoxide dismutase (SOD), and other antioxidative systems, leading to an increase in lipid peroxidation. We analyzed the effects of protein deficiency on liver Cu, Fe, Zn, Mn, and Se in carbon tetrachloride (CCl₄)-induced liver cirrhosis, the relation of protein undernutrition and these trace elements with the activity of some hepatic antioxidative enzymatic mechanisms, and the relation of all of them with morphological and biochemical changes in 40 male adult Sprague-Dawley rats divided in four groups. Liver cirrhosis was induced by intraperitoneal injection of CCl₄ to 10 rats fed a 2% protein diet and another 10 fed a 18% protein control diet; two further groups included rats without cirrhosis fed the 2% protein and the 18% protein diets. The study period lasted 6 wk. GPX, SOD, and lipid peroxidation products as well as Zn, Cu, Mn, Se, and Fe were determined in liver samples. We found that liver GPX and Se were reduced in the cirrhotic animals, especially in the low-protein-fed ones, protein deficiency, but not cirrhosis, exerting the main effects. A close correlation was found between liver GPX and serum albumin and weight loss and an inverse one among GPX and hepatocyte ballooning, liver fibrosis, and fat, histomorphometrically determined. These results suggest a pathogenetic role of decreased GPX in the progression of liver disease, which may become enhanced by concomitant protein undernutrition. In addition to iron, the levels of which were increased in the malnourished rats, no differences were found regarding the other trace elements, SOD activity, and lipid peroxidation products.     

Phenotypic plasticity of invasive Carpobrotus edulis modulates tolerance against herbivores

The anthropogenic movement of species has favoured the introduction of invasive plants worldwide. Invasive plants are frequently released from their natural enemies; however, new associations with generalist herbivores may induce defence mechanisms of non-native plants. Defensive traits are often directly related to the highly competitive ability, but also to potential antagonisms and mutualisms that they can establish with soil microorganisms. Here, we examined whether the intraspecific competition and soil microorganisms influence the morphological and physiological traits of Carpobrotus edulis when is being attacked by the native generalist snail Theba pisana. To achieve this, we grew two C. edulis individuals in separate and same pots filled with live or sterile sand, and with or without T. pisana. Our results indicated that herbivory induced an increase of shoot biomass in attacked C. edulis individuals (i.e., treated donor plants), as well as in un-attacked neighbouring individuals co-growing in the same pot (i.e., untreated recipient plants). Nevertheless, intraspecific competition nor soil microorganisms did not affect the growth of C. edulis despite reduced physiological activity and damage caused by the herbivore. Overall, our findings revealed that C. edulis individuals tolerate snail attack by inducing a compensatory growth response. We conclude that phenotypic plasticity of invasive C. edulis favours tolerance against herbivores, but we also suggest that plant-plant interactions probably determine the plant growth of un-attacked neighbouring C. edulis individuals, thus favouring their invasion mechanisms.

     

Age and growth of invasive round goby <Emphasis Type="Italic">Neogobius melanostomus</Emphasis> from middle Danube

Age and growth of the invasive population of round goby Neogobius melanostomus from the Slovak stretch of River Danube was examined. The samples (n=1130) were collected soon after the invasion was recorded (2004–2005), and later, when the population was already established (2008–2010). Invasive round goby in newly-occupied areas were found to reach smaller body size (15–153 mm standard length) compared to native populations. Age from 0+ to 4+, determined from scales, was recorded in both sexes. Annulus formed in April–May, which varied with age. Growth of freshly established gobies was negative allometric, suggesting increased allocation of their sources to reproduction, which corresponds to less specialized life-history. However, positive allometric growth found in longer established individuals suggests a shift in allocation towards somatic growth, which corresponds to more specialized life-history typical for native populations. None of the three parameters predicted by the theory of alternative ontogenies and invasive potential met the expectations, though two parameters, i.e. growth rate and age at maturation remain equivocal. This can be explained by too short of a time span that has elapsed from the beginning of invasion, or by ecological disturbances that have broken up otherwise stable environment in the habitat studied.