Ultrastructure of Enteromyxum leei (Diamant, Lom, & Dyková, 1994) (Myxozoa), an Enteric Parasite Infecting Gilthead Sea Bream (Sparus aurata) and Sharpsnout Sea Bream (Diplodus puntazzo)

ABSTRACT. The ultrastructure of the developmental stages of the myxozoan Enteromyxum leei parasitizing gilthead seabream ( Sparus aurata ) intestine and sharpsnout sea bream ( Diplodus puntazzo ) intestine and gallbladder are described. The earliest stage observed was a small dense trophozoite located among enterocytes. Proliferative stages, observed intercellularly in the epithelium of the intestine and gallbladder as well as in the lumen, possessed the typical cell-in-cell configuration throughout their development. Secondary cells were seen undergoing division within a common vacuolar membrane that also encompassed pairs of tertiary cells. Cytochemical studies showed that primary cells stored mainly lipids whereas secondary cells stored abundant β-glycogen granules. Sporogonic development resembled that described for other disporous myxozoans. Within sporogonic stages, nonsporogonic secondary cells were observed accompanying two developing spores. Mature spores had a binucleated sporoplasm in which glycogen stores were abundant and no sporoplasmosomes were found. Our observations are discussed in relation to our knowledge on other myxozoans of the genus Enteromyxum .     

Geographic analysis of nucleotide diversity and song sparrow (Aves: Emberizidae) population history

Mitochondrial DNA (mtDNA) control-region (CR) sequences were analysed to address three questions regarding the evolution of geographical variation in song sparrows. (i) Are mtDNA sequences more informative about phylogenetic relationships and population history than previously published restriction fragment (RFLP) data? (ii) Are song sparrow CR sequences evolving in a selectively neutral manner? (iii) What do the haplotype cladogram and geographical pattern of nucleotide diversity (π) suggest about the recent evolutionary history of song sparrow populations? Results from phylogenetic analyses of CR sequences corroborate RFLP results and reveal instances in which haplotypes do not group by locality. Neutrality tests ( 51 ) suggest that song sparrow mtDNA is evolving in a selectively neutral manner, although exceptions are noted. A novel geographical pattern of π suggests a model of song sparrow population history involving multiple Pleistocene refugia and colonization of some formerly glaciated regions from multiple sources. Moreover, application of coalescence theory to the haplotype cladogram suggests that two different haplotypes (48NF and 151HA) may have predominated in different parts of the song sparrow's range. This model provides insight into the current distribution of song sparrow mtDNA haplotypes and may explain the discordance between evolutionary history inferred from mtDNA and morphology in this species.     

Early Triassic vertebrate burrows from the Katberg Formation of the south‐western Karoo Basin,South Africa

Bordy, E.M., Sztanó, O., Rubidge, B.S. & Bumby, A. 2010: Early Triassic vertebrate burrows from the Katberg Formation of the south‐western Karoo Basin, South Africa. Lethaia, Vol. 44, pp. 33–45. Very large (～30–35 cm), uniform diameter cylindrical burrows were found at two localities, ～100–110 m above Permo‐Triassic boundary in the fluvial Katberg Formation (main Karoo Basin, South Africa). Analysis of their morphology and stratigraphical distribution allows us to improve both the understanding of the ethology of burrowing, and also the reconstruction of the earliest Triassic ecosystems. These burrows have a single opening that leads, via a large, uniform diameter, semi‐horizontal tunnel, to a rounded terminus. These 3‐m‐long structures descend at angles of ～30° to a maximum of 1.5 m depth. They are devoid of chambers, branching, cross‐cutting, coiling or spiralling. Filled with coarse sediments, some have a <5‐mm clay lining, and most have subtle indentations and various scratch marks. These burrows were possibly excavated as resting, hiding or aestivating shelters, and are tentatively attributed to dicynodonts (i.e. Lystrosaurus murrayi and L. declivis). Data suggest that burrowing was widespread after the P/Tr boundary event, when in this part of Gondwana, dryland fluvial systems had large fluctuations in flow with extended low‐flow periods or drought punctuated by high‐discharge periods. We hypothesize that these constructed refuges played a role in the biodiversity recovery and maintenance in the Early Triassic (Induan) ecosystem. □Early Triassic, Karoo Basin, Katberg Formation, South Africa, Tetrapod Burrows.     

Elevationally biased avian predation as a contributor to the spatial distribution of geometrid moth outbreaks in sub‐arctic mountain birch forest

1. Population dynamics and interactions that vary over a species' range are of particular importance in the context of latitudinal clines in biological diversity. Winter moth (Operophtera brumata) and autumnal moth (Epirrita autumnata) are two species of eruptive geometrids that vary widely in outbreak tendency over their range, which generally increases from south to north and with elevation. 2. The predation pressure on geometrid larvae and pupae over an elevational gradient was tested. The effects of background larval density and bird occupancy of monitoring nest boxes on predation rates were also tested. Predation on larvae was tested through exclusion treatments at 20 replicate stations over four elevations at one site, while pupae were set out to measure predation at two elevations at three sites. 3. Larval densities were reduced by bird predation at three lower elevations, but not at the highest elevation, and predation rates were 1.9 times higher at the lowest elevation than at the highest elevation. The rate of predation on larvae was not related to background larval density or nest box occupancy, although there were more eggs and chicks at the lowest elevation. There were no consistent differences in predation on pupae by elevation. 4. These results suggest that elevational variation in avian predation pressure on larvae may help to drive elevational differences in outbreak tendency, and that birds may play a more important role in geometrid population dynamics than the focus on invertebrate and soil predators of previous work would suggest.     

Phylogeny and evolution of phytophagous ladybird beetles (Coleoptera: Coccinellidae: Epilachnini), with recognition of new genera

Phytophagous ladybird beetles of the tribe Epilachnini are a cosmopolitan, species‐rich group of significant economic importance as pests of agricultural crops. The tribe is well characterized morphologically and clearly monophyletic, but very little is known about its internal phylogenetic relationships and their genus‐level taxonomy. In order to infer the evolutionary history of Epilachnini, test its monophyly and provide a phylogeny‐based classification, we assembled a comprehensive dataset, consisting of four DNA markers (18S and 28S rRNA and 16S, COI mtDNA) and a matrix of 104 morphological characters for 153 species of Epilachnini representing all previously recognised genera, ～11% of the known species, and 14 outgroup taxa. Molecular, morphological and combined datasets were analysed using maximum likelihood, parsimony and Bayesian inference. Bayes factors and Approximately Unbiased tests (AU) were used to compare alternative phylogenetic hypotheses of unconstrained and backbone‐constrained analysis. Only 14 of the 25 included genera were recovered monophyletic, as originally defined. Afidentula Kapur, Afidenta Dieke, Afissula Kapur, Epilachna Chevrolat, Henosepilachna Li Toxotoma Weise and Mada Mulsant are shown to be poly‐ or paraphyletic; Chnootriba Chevrolat, Subafissa Bielawski, Lalokia Szawaryn & Tomaszewska and Papuaepilachna Szawaryn & Tomaszewska form monophyletic groups within larger clades of genus level. All of these genera are redefined here. The two largest genera of Epilachnini, Epilachna Chevrolat and Henosepilachna Li were represented by multiple monophyletic clades, which we described as new genera: Chazeauiana Tomaszewska & Szawaryn gen.n. ; Diekeana Tomaszewska & Szawaryn gen.n .; Fuerschia Tomaszewska & Szawaryn gen.n. and Ryszardia Tomaszewska & Szawaryn gen.n . The following new synonyms are proposed: Afissa Dieke (=Afissula Kapur); Henosepilachna Li in Li & Cook (=Subafissa Bielawski); Papuaepilachna Szawaryn & Tomaszewska (=Lalokia Szawaryn & Tomaszewska). This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:440E7FA4‐C859‐47E0‐8335‐30D478CBA8FA .     

Opportunities for mate choice in the fission‐performing ant Cataglyphis cursor

1. Sexual selection has been little studied in social insects. Nonetheless, because mating is generally for life, opportunities for selecting among mating partners should be exploited. 2. In some ants, males aggregate at nest entrances to mate with emerging gynes. Both males and females thus have access to multiple mates over a relatively protracted period, giving rise to opportunities for mate choice and multiple mating. 3. We provide data from field observations of the male mating biology of the ant, Cataglyphis cursor Fonscolombe. In this species, females mate with, on average, six males each at the nest entrance and found colonies with the help of workers. 4. Males were present at the field site for approximately 1 month in spring, with up to 40 males at a single nest entrance for, on average, 4.7 days. Individual males were observed to survive up to 3 days, and mate up to eight times. 5. Thus both males and females of this species have the ability to mate multiply and have a window permitting mate choice to occur. Workers actively attacked males and may take part in the mate choice process, making C. cursor an interesting model to study questions relating to sexual selection and male mating strategies.     

Plasticity of opsin gene expression in cichlids from Lake Malawi

Sensory systems play crucial roles in survival and reproduction. Therefore, sensory plasticity has important evolutionary implications. In this study, we examined retinal plasticity in five species of cichlid fish from Lake Malawi. We compared the cone opsin expression profiles of wild‐caught fish to lab‐reared F₁ that had been raised in a UV minus, reduced intensity light environment. All of the opsin genes that were expressed in wild‐caught fish were also expressed in lab‐reared individuals. However, we found statistically significant differences in relative opsin expression among all five species. The most consistent difference was in the SWS2B (violet) opsin, which was always expressed at higher levels in lab‐reared individuals. Estimates of visual pigment quantum catch suggest that this change in expression would increase retinal sensitivity in the light environment of the lab. We also found that the magnitude of plasticity varied across species. These findings have important implications for understanding the genetic regulation of opsin expression and raise many interesting questions about how the cichlid visual system develops. They also suggest that sensory plasticity may have facilitated the ecological diversification of cichlids in Lake Malawi.     

Monoclonal antibodies against tomato spotted wilt virus: Characterisation and application*

Mouse hybridoma cells, secreting monoclonal antibodies (MCA) against tomato spotted wilt virus, were produced and screened for virus specificity by an indirect triple antibody ELISA, using a rabbit polyclonal antiserum for antigen trapping. A Bulgarian virus isolate from tobacco was used for immunisation of mice and rabbits. One fusion eventually led to 10 stable hybridoma cell lines, all of which produced antibodies of IgG-type though of different subgroups. Since none of the MCAs reacted with TSWV structural proteins after electrophoresis and transfer to nitrocellulose, other methods were chosen to examine their protein specificity. Purified viral cores and detergent-solubilised envelope proteins were used as antigens for ELISA, or, alternatively, glycosylated viral envelope proteins were trapped onto microtitre plates coated with lectins in order to detect MCAs specific for them. Both methods, independently, led to the identification of two MCAs that were specific for envelope proteins of TSWV. Only these two antibodies reacted with intact TSWV particles when examined by immunogold labelling in the electron microscope. The reaction of all MCAs with 11 different TSWV isolates eventually led to the selection of one core- and one envelope-specific antibody for routine use. Core-specific MCAs revealed serological differences between isolates belonging to the common serotype (= lettuce serotype), but did not react with the serotype TSWV-I. When comparing different ELISA procedures, broadest reactivity and highest sensitivity with different isolates were obtained in an indirect test procedure, using goat anti-mouse antibody conjugates.     

The Response of the Primary Root Meristem of Zea mays L. to Various Periods of Cold

Primary roots of maize (Zea mays L.) grown in nutrient solutionat 5?C elongate at about 1% of the rate found at 20?C. The apicalmeristem becomes shorter and shows little proliferative activityat 5?C, but following transfer to 20?C mitoses increase in frequencyand the meristem regrows to its original length. Both the amountby which the meristem shortens and the time for its completeregrowth are related to the period spent at 5?C. The shorteningof the meristem suggests that at the lower temperature the balancewhich normally exists between cell production and differentiationis altered, the latter continuing at a relatively faster ratethan the former. A new, steady-state balance between the twoprocesses is re-established during the recovery period. Themeristem recovers as a result not only of its own mitotic activitybut also through stimulation of cell division in the quiescentcentre. The degree to which the quiescent centre is activated,as judged by its mitotic index and the number of nuclei labelledby feeding with tritiated thymidine, increases as the durationof the preceding cold treatment increases. The close relationshipbetween proliferative activity in the quiescent centre and theminimum length of the meristem following the cold treatmentsuggests that there is communication between these two zoneswhich co-ordinates their respective rates of cell productionand helps to maintain a normal meristem structure. The resultsemphasize the importance of the quiescent centre as a reservoirof cells that can re-establish a meristem rendered non-functionalthrough the impact of unfavourable environmental conditions. Key words: Meristem, quiescent centre, root, temperature, Zea mays