Free Radicals in the Root System and Stem of Zea mays

The concentration of free radicals in different parts of theroot system and the stem of 130, 158 and 165 d old maize plantswere measured. The highest concentrations of free radicals werefound in the tissue of the primary root and in the adventitiousroots of the 1st and 2nd nodes. In the stem tissues, the highestconcentration of free radicals was found in the tissues of the14th to 15th internode. The concentration of free radicals inthe tissues of the nodal roots decreased with increasing nodenumber, whereas in the tissues of the overground stem it increasedwith internode number. This pattern may be correlated with themetabolic activity of tissues.     

A comparison of sampling methods with respect to cattle-visiting Muscidae and their nematode infections

Abstract. Cattle-visiting Muscidae were sampled with a handnet from a blood-smeared Masonite panel as well as grazing heifers and dairy cows in south-central Sweden. All flies were examined in search of nematodes. Only Musca autumnalis was infected with nematodes (Parafilaria bovicola, Thelazia spp. and Hetero-tylenchus autumnalis). The only mixed infections found involved P.bovicola and Thelazia spp. Most M.autumnalis infected with P.bovicola and Thelazia spp. were found during the two first months of the grazing season, whereas the prevalence of specimens infected with H.autumnalis remained about the same throughout the sampling period. Musca autumnalis was caught in significantly smaller numbers from heifers (P< 0.05) than from panel and cows. The catches of nematode-infected M.autumnalis were similarly distributed. Catches of other cattle-visiting Muscidae did not differ significantly among the methods used. Handnet sampling off a panel is therefore considered to be a convenient and accurate method when investigating the abundance of cattle-visiting Muscidae and the prevalence of their nematode infections.     

The external morphology of the parasitic copepod Holobomolochus confusus (Stock)

Holobomolochus confusus is reported for the first time from the western Atlantic coasts. The external morphology, especially that of the male, of specimens from the nasal cavities of cod, Gadus morhua , from the west coast of Sweden is described and discussed. Sexual dimorphism occurs in the maxillipeds, abdomen, first antenna and in the armature of the legs. The results indicate that the species has a good swimming ability and that this may allow the male especially to change hosts.     

Comparison of male and female olfactory cell response to pheromone compounds and plant volatiles in the turnip moth, Agrotis segetum

ABSTRACT. Pheromone and plant volatile perception was studied with electroantennogram and single sensillum techniques in male and female turnip moths, Agrotis segetum Schiff. Lepidoptera, Noctuidae. The female is insensitive to the pheromone components and her receptors are specialized for plant volatile reception. The specific pheromone receptors on the male antenna are also sensitive to plant volatiles. The male was in addition found to have specialized plant volatile receptors. The biological significance of the different response profiles in males and females, and a possible hypothesis for the evolutionary specialization of olfactory receptors are discussed.     

Metazoan evolution–a new model

Within their limits of resolution, different methods to reveal biochemical evolution appear to give reliable results where they can be controlled, as in the case of the Vertebrata. Compounds such as cytochrome c, SS rRNA and globins yield closely comparable results, which further strengthens the reliability. When the methods are applied to biochemical data from as many metazoan phyla as possible, the result is a phylogenetic tree which contrasts in certain respects with phylogenetic trees based on comparative zoology data. Important conclusions seem to include the following: (1) many metazoan phyla appear to have branched off from a shared, very conservative spiralian/protostome ancestral stock through the adoption of basically new feeding and locomotory strategies; (2) this origination makes it almost impossible to use a comparative zoology approach to solve problems of interphylum (in contrast to intraphylum) affinities, as similarities tend to be due only to shared derived Characters and similar life strategies, while dissimilarities are due to different basic life strategies; (3) protostome characters constitute a synapomorphy for triploblastic metazoans, and where absent they are secondarily lost, which means that protostome and deuterostome characters are irregularly distributed and mixed; (4) true deuterostomes form a sister group of the Mollusca, and they are only a top branch of the evolutionary tree.     

The Life Cycle of Rotaliella elatiana N. Sp.: A Tiny Macroalgavorous Foraminifer from the Gulf of Elat1

ABSTRACT. A new foraminiferan species, Rotaliella elatiana n. sp., was isolated in the Gulf of Elat, where it lives in association with a macrophytic green alga, Enteromorpha. The agamont of this tiny new species has a transparent test composed of a bilocular embryonic chamber followed by six to seven trochospirally coiled inflated chambers. The spiral sutures are undulated. The umbilical side has numerous denticules and has radial grooves. The gamont has only one inflated chamber. Rotaliella elatiana has a classical, heterophasic life cycle, with a regular alternation of diploid agamontic phase and haploid gamontic phase. The gamontic phase of the life cycle is exceptionally reduced and the uninucleated gamonts pair immediately after they build their first chamber. A few cases of autogamic reproduction were observed. R. elatiana is a heterocaryotic species; agamonts have one somatic and two to three generative nuclei.