Regressive astogenese beiNudonychocella n.g.n.sp. und anderen bryozoen aus der tuffkreide von maastricht

Nudonychocella nuda n.g.n.sp. from the Maastrichtian chalk tuff is a cheilostome bryozoan species which shows totally opened “membranimorph” zooecia and avicularia. Its ancestrula, however, displays — likeOnychocella Jullien — semicircular opesiae and normally formed calcified frontal walls (cryptocysts), revealing its lineage from this genus which belongs to the Coilostega. This is suggested to be a matter of regressive astogeny, unknown until now in bryozoology, during which the calcareous cryptocyst, being characteristic for that genus, was totally reduced.Onychocella cyclostoma (Goldf.) andO. koninckiana (v. Hagenow) also show the tendency to reduce their calcareous frontal walls which are still widely normal during the neonastic stage of the colony. InCastanopora bipunctata (GOLDF.), however, the cribrimorph frontal shield may disappear totally. A satisfactory explanation of this phenomenon may be that the neonastic stage characterising the peripheral growing tip of the colony with its incompletely calcified frontal walls of the zooids dominated the whole colony, induced by a stop of the calcification of the cryptocyst, with the exception of the ancestrula, the result of which being a secondary membranimorph stage, characteristic for the Malacostega. The reduction of the calcification does not contradict to Dollo’s rule concerning the irreversibility of the evolution. Consequences arising for taxonomic questions and phylogenetic research are discussed.     

FMRF-amide immunoreactivity pattern in the planula and colony of the hydroid Gonothyraea loveni

Gonothyraea loveni (Allman, 1859) is a colonial thecate hydrozoan with a life cycle that lacks a free-swimming medusa stage. The development from zygote to planula occurs within meconidia attached to the female colony. The planula metamorphosis results in the formation of a primary hydranth. The colony then grows by development of new colony elements. In the present work, we studied the temporal pattern of the formation of FMRF-amide-positive cells during embryogenesis, in larvae and during early colony ontogeny. FMRF-amide-positive cells appear in the planula only after its maturation. However, they disappear after planula settlement. For the first time, we show that neural cells are present in the coenosarc of the hydroid colony. We also trace the process of neural net formation during the development of a new shoot internode of the G. loveni colony.     

Arabinose-rich polymers as an evolutionary strategy to plasticize resurrection plant cell walls against desiccation

A variety of Southern African resurrection plants were surveyed using high-throughput cell wall profiling tools. Species evaluated were the dicotyledons, Myrothamnus flabellifolia and Craterostigma plantagineum; the monocotyledons, Xerophyta viscosa, Xerophyta schlecterii, Xerophyta humilis and the resurrection grass Eragrostis nindensis, as well as a pteridophyte, the resurrection fern, Mohria caffrorum. Comparisons were made between hydrated and desiccated leaf and frond material, with respect to cell wall composition and polymer abundance, using monosaccharide composition analysis, FT-IR spectroscopy and comprehensive microarray polymer profiling in combination with multivariate data analysis. The data obtained suggest that three main functional strategies appear to have evolved to prepare plant cell walls for desiccation. Arabinan-rich pectin and arabinogalactan proteins are found in the resurrection fern M. caffrorum and the basal angiosperm M. flabellifolia where they appear to act as ‘pectic plasticizers’. Dicotyledons with pectin-rich walls, such as C. plantagineum, seem to use inducible mechanisms which consist of up-regulating wall proteins and osmoprotectants. The hemicellulose-rich walls of the grass-like Xerophyta spp. and the resurrection grass E. nindensis were found to contain highly arabinosylated xylans and arabinogalactan proteins. These data support a general mechanism of ‘plasticising’ the cell walls of resurrection plants to desiccation and implicate arabinose-rich polymers (pectin-arabinans, arabinogalactan proteins and arabinoxylans) as the major contributors in ensuring flexibility is maintained and rehydration is facilitated in these plants.     

Wachstums- und Knospungsstrategie vonGrammothoa filifera Voigt & Hillmer (Bryozoa,Cheilostomata, Ob. Kreide)

The genusGrammothoa, growing on the interior walls ofThalassinoides burrows in the Maastrichtian Chalk-tuff, has developed a special growth strategy for spatial competition with other encrusting species which has not been previously recorded in bryozoans. The zoarium consists of auto-zooecia, gynozooecia and chains of smaller zooeciules, the latter forming stolon-like outgrowths from the distal edge of the colony. New areas of substratum are explored and colonized by the growth of these zooeciules. At the branching points of the zooeciules, autozooecia and gynozooecia are budded and may coalesce to form the main part of the colony.     

Field observation of predation on paper wasp nests by introduced terrestrial slugs

Nest predation is an important factor in the colony mortality of paper wasps. Although a variety of animals are known to prey on paper wasp nests, colony failure of unknown cause often occurs in the field, and the existence of still-unknown predators is possible. Here, I report predation on nests of paper wasps, Polistes chinensis antennalis, by introduced terrestrial slugs, Lehmannia valentiana. The slugs were found on the wasps’ nests despite the presence of the owners on the nests and ate eggs, larvae, and presumably cell walls of the nests. This is the first report of predation on paper wasp nests by slugs.     

Multizooidal Budding in Parasmittina trispinosa (Johnston) (Bryozoa,Cheilostomata)

Two principally different wall types occur in the bryozoan colony: Exterior walls delimiting the super-individual, the colony, against its surroundings and interior walls dividing the body cavity of the colony thus defined into units which develop into sub-individuals, the zooids. In the gymnolaemate bryozoans generally, whether uniserial or multiserial, the longitudinal zooid walls are exterior, the transverse (proximal and distal) zooid walls interior ones. The radiating zooid rows grow apically to form “tubes” each surrounded by exterior walls but subdivided by interior (transverse) walls. The stenolaemate bryozoans show a contrasting mode of growth in which the colony swells in the distal direction to form one confluent cavity surrounded by an exterior wall but internally subdivided into zooids by interior walls. In the otherwise typical gymnolaemate Parasmittina trispinosa the growing edge is composed of a series of “giant buds” each surrounded by exterior walls on its lateral, frontal, basal and distal sides and forming an undifferentiated chamber usually 2–3 times as broad and 3 or more times as long as the final zooid. Its lumen is subdivided by interior walls into zooids 2–3, occasionally 4, in breadth. This type of zooid formation is therefore similar to the “common bud” or, better-named, “multizooidal budding” characteristic of the stenoleamates but has certainly evolved independently as a special modification of the usual gymnolaemate budding.     

Attack or retreat: contrasted defensive tactics used by Cyprian honeybee colonies under attack from hornets

This study describes the tactics used by Cyprian honeybees (Apis mellifera cypria) to defend their colonies against hornet (Vespa orientalis orientalis) attacks. We use simulated hornet attacks and a combination of video recordings and image analysis to reveal, for the first time, contrasted intra-subspecies defensive tactics that operate at the colony level during predation. In some colonies, when attacked, the numbers of guards at the hive entrance increases rapidly to attack, engulf, and kill invading hornets. In other colonies, guards avoid conflicts with hornets by retreating gradually and by forming a defensive line of honeybees at the hive entrance. Retreater colonies have propolis walls at the hive entrances with small apertures that are too narrow to allow the hornet to access the hive and that therefore reinforces entrance protection. On the contrary, attacker colonies have propolis walls with large openings through which the hornet can pass; these bees block the hornet's access by intensively guarding the hive entrance. We experimentally destroy propolis walls to test whether colonies consistently rebuild walls with the same intrinsic characteristics and we also monitor the survival rate of each anti-predator tactic after massive natural predation by hornets.     

Bacteriocin-Related Siblicide in Clinical Isolates of Enterococci

Siblicide is a phenomenon defined in the present context as an Enterococcus strain that, while growing as a colony on solid media, exhibits an inhibitory effect on a lawn composed of the identical strain. It was shown to occur in seven clinical isolates of enterococci (one E. faecalis and six E. faecium). Four involve inhibitory anti-listerial activities consistent with class II bacteriocins, two of which appear to be up-regulated by extracellular autoinducers.     

Extracytoplasmic phosphatases of selected species of Saccharomyces, Kluyveromyces and Rhodotorula

Phosphatase activities of yeasts belonging to the genera Saccharomyces, Kluyveromyces and Rhodotorula were studied. Rhodotorula rubra exhibited activities at acid, neutral and alkaline pH; the other yeasts only had activity at acid pH. Growing yeasts in a constant pH (4.5) medium decreased phosphatase activities in Saccharomyces and Kluyveromyces, while neutral activity was enhanced in Rhodotorula rubra which excreted more enzyme under these conditions. Washing cells with sucrose solutions lowered phosphatase activities in all yeasts, due to enzyme liberation. Acid phosphatase activities in isolated and purified cell walls were very small. Phosphatases thus appear not to be strongly bound to yeast cell walls.     

Changes of RNA virus infection rates and gut microbiota in young worker Apis mellifera (Hymenoptera: Apidae) of a chalkbrood-infected colony after a pollination task in a greenhouse

Western honey bee (Apis mellifera Linnaeus) populations recently have been in decline worldwide owing not only to colony collapse disorder but also other infectious diseases. The problem is neither decreasing nor has it been resolved. Chalkbrood (Ascosphaera apis, Maassen ex Claussen) is a well-known fungal brood disease that is now found throughout the world, and there are indications that the incidence of chalkbrood may be on the rise. Here, we conducted comparative studies to analyze infection rates of pathogenic RNA viruses and gut microbiota of young worker honey bees in two colonies: a healthy control colony raised in an open field and a test colony showing the chalkbrood symptom after a 2-month pollination task in a strawberry greenhouse. We found that the number of young worker bees with deformed wing virus (DWV) RNA was significantly elevated in the chalkbrood-infected colony, and two kinds of gut γ-proteobacteria, Frischella perrara gen. nov. and Pasteurellaceae bacterium Trm1, were especially increased in DWV-infected animals. These results showed that the DWV infection rates of worker honey bees were enhanced when their brood was infected with chalkbrood disease and that the gut microbiota in worker bees was significantly affected by the virus infection.     

Evaluation of the Distribution and Impacts of Parasites,Pathogens, and Pesticides on Honey Bee (Apis mellifera) Populations in East Africa

In East Africa, honey bees (Apis mellifera) provide critical pollination services and income for small-holder farmers and rural families. While honey bee populations in North America and Europe are in decline, little is known about the status of honey bee populations in Africa. We initiated a nationwide survey encompassing 24 locations across Kenya in 2010 to evaluate the numbers and sizes of honey bee colonies, assess the presence of parasites (Varroa mites and Nosema microsporidia) and viruses, identify and quantify pesticide contaminants in hives, and assay for levels of hygienic behavior. Varroa mites were present throughout Kenya, except in the remote north. Levels of Varroa were positively correlated with elevation, suggesting that environmental factors may play a role in honey bee host-parasite interactions. Levels of Varroa were negatively correlated with levels of hygienic behavior: however, while Varroa infestation dramatically reduces honey bee colony survival in the US and Europe, in Kenya Varroa presence alone does not appear to impact colony size. Nosema apis was found at three sites along the coast and one interior site. Only a small number of pesticides at low concentrations were found. Of the seven common US/European honey bee viruses, only three were identified but, like Varroa, were absent from northern Kenya. The number of viruses present was positively correlated with Varroa levels, but was not correlated with colony size or hygienic behavior. Our results suggest that Varroa, the three viruses, and Nosema have been relatively recently introduced into Kenya, but these factors do not yet appear to be impacting Kenyan bee populations. Thus chemical control for Varroa and Nosema are not necessary for Kenyan bees at this time. This study provides baseline data for future analyses of the possible mechanisms underlying resistance to and the long-term impacts of these factors on African bee populations.     

Honeybee (Apis cerana) guards do not discriminate between robbers and reproductive parasites

A hopelessly queenless honeybee colony has only one reproductive option: some workers must produce sons before the colony dies. This requires the workers to curtail egg policing (removal of worker-produced eggs), rendering the colony vulnerable to non-natal reproductive parasitism. In the Western honeybee, Apis mellifera, guarding (prevention of foreign workers from entering a colony) increases in queenless colonies, providing a defence against non-natal parasitism. However, in the closely related Eastern honeybee A. cerana, queenless colonies appear to be more tolerant of bees from other colonies. We presented guards of four A. cerana colonies with three types of workers: nestmate returning foragers, non-nestmate returning foragers and non-nestmates from a laying-worker colony. The latter are likely to have active ovaries, allowing us to test whether guard bees can detect which potential invaders are more likely to be reproductive parasites. After assessing guards’ reactions, we recaptured test bees and dissected them to determine levels of ovary activation. We found that nestmates were accepted significantly more frequently than the other two types of workers. However, there was no difference in the overall acceptance rates of non-nestmate returning foragers and bees from within laying-worker colonies. In addition, ovary-activated workers were no less likely to be accepted than those with inactive ovaries. Interestingly, colonies were more accepting of all three types of test bee after being made queenless. We conclude that, as has been previously suggested, guarding has no specific role in the prevention of non-natal parasitism in A. cerana.     

The cell wall of Chlamydomonas eugametos. Immunological aspects

An antiserum was raised against the major cell wall glycoprotein of Chlamydomonas eugametos which after purification reacted specifically with all individual wall components but not with intact cell walls. The antigenic sites in intact walls appear to be cryptic but become exposed on partial enzymatic degradation or in situ during daughter-cell release when the insoluble component is digested. Using the antiserum as a specific label for cell walls in various stages of disintegration, cell wall digestion during asexual and sexual reproduction was studied. It is also shown that while cell wall material is associated with isolated flagella, it is not normally associated with the flagella of intact cells.     

Pachyteichopora n. g. (Bryoz. Cyclostomata) aus der oberen Kreide

The cyclostome Bryozoan speciesPustulopora verrucosa, described by Roemer 1840, is combined with two other congeneric species within the new genusPachyteichopora (type-speciesP. verrucosa [Roemer]). This new genus characterized by its extremely highly calcified external walls of the erect massive cylindrical and dichotomously branched zoaria possessing maculae. The similarity of its gonozooid to that ofLeiosoecia counts for its provisional attribution to the Fam. Leiosoeciidae Canu & Bassler (1920).P. bugei n. g. n. sp. from the French Coniacian andP. punctata n. g. n. sp. from the Swedish Campanian are described.     

The alanine ester content and magnesium binding capacity of walls of Staphylococcus aureus H grown at different pH values

Recent studies have shown that teichoic acids are functionally involved in the uptake of Mg²⁺ and that their ability to bind Mg is reduced by the presence of alanine ester substituents. Walls of Staphylococcus aureaus H grown at pH 5 contain more ester alanine and bind less magnesium than do walls of S. aureaus grown under similar conditions at pH 6 and 7. The differences in alanine content are largely due to its removal by base catalysed hydrolysis of the labile ester linkages during growth in media of pH 6 and 7 and the incorporation of alanine esters into the walls does not appear to be influenced by the pH of the medium in which the bacteria are grown under the conditions described. The decreased magnesium binding capacity of walls of S. aureus grown at pH 5 correlates with their increased alanine ester content but there is no proportional relationship between these two quantities.     

Molecular phylogenetic evidence supports a new family of octocorals and a new genus of Alcyoniidae (Octocorallia,Alcyonacea)

Molecular phylogenetic evidence indicates that the octocoral family Alcyoniidae is highly polyphyletic, with genera distributed across Octocorallia in more than 10 separate clades. Most alcyoniid taxa belong to the large and poorly resolved Holaxonia–Alcyoniina clade of octocorals, but members of at least four genera of Alcyoniidae fall outside of that group. As a first step towards revision of the family, we describe a new genus, Parasphaerasclera gen. n., and family, Parasphaerascleridae fam. n., of Alcyonacea to accommodate species of Eleutherobia Pütter, 1900 and Alcyonium Linnaeus, 1758 that have digitiform to digitate or lobate growth forms, completely lack sclerites in the polyps, and have radiates or spheroidal sclerites in the colony surface and interior. Parasphaerascleridae fam. n. constitutes a well-supported clade that is phylogenetically distinct from all other octocoral taxa. We also describe a new genus of Alcyoniidae, Sphaerasclera gen. n., for a species of Eleutherobia with a unique capitate growth form. Sphaerasclera gen. n. is a member of the Anthomastus–Corallium clade of octocorals, but is morphologically and genetically distinct from Anthomastus Verrill, 1878 and Paraminabea Williams & Alderslade, 1999, two similar but dimorphic genera of Alcyoniidae that are its sister taxa. In addition, we have re-assigned two species of Eleutherobia that have clavate to capitate growth forms, polyp sclerites arranged to form a collaret and points, and spindles in the colony interior to Alcyonium, a move that is supported by both morphological and molecular phylogenetic evidence.     

The long engagement of the emperor penguin

In birds, courtship is generally short relative to the whole breeding cycle. Emperor penguins (Aptenodytes forsteri), however, are an exception as their courtship period is much longer (ca. 6 weeks) than the courtship of other penguin species. This strategy may appear surprising, as it is especially costly to fast and endure drastic climatic conditions for long periods at the colony (1.5 and up to 4 months for females and males, respectively). We examined here the reasons of this extended courtship period and found that emperor penguins returned earlier to the colony when primary oceanic production before breeding was high. This suggests that emperor penguins return to the colony as soon as primary oceanic production in summer allows them to replenish their body reserves. The extended period of time spent at the colony during courtship may therefore result from an evolutionary process that confers advantages to emperor penguins that arrive earlier at the colony by reducing predation risks and offering better chances of securing a partner.     

Identification of polysaccharide hydrolases involved in autolytic degradation of zea cell walls

Cell walls of Zea mays (cv L.G.11) seedlings labeled with ¹⁴C were treated with α-amylase from Bacillus subtilis to remove starch and mixed linkage glucans. These walls released arabinose, xylose, galactose, and galacturonic acid in addition to glucose when they were allowed to autolyze. Methylation analysis was performed on samples of wall which had been incubated autolytically and the results indicated that degradation of the major polymer of the wall, the glucoarabinoxylan, had occurred. A number of glycanases could be dissociated from the wall by use of 3 m LiCL. The proteins which were released were found to contain a number of exoglycosidase activities in addition to being effective in degrading the polysaccharide substrates, araban, xylan, galactan, laminarin, mannan, and polygalacturonic acid. The effects of these enzymes on the wall during autolysis appear to result from endo-activity in addition to exo-activity. The structural changes that occurred in the cell walls during autolysis were found to be related to the changes previously found to occur in cell walls during auxin induced extension.     

Description of Pella maoershanensis sp. n. (Coleoptera,Staphylinidae, Aleocharinae) associated with Lasius spathepus from Guangxi,South China

Pellamaoershanensis Song & Li, sp. n., collected from a colony of Lasius (Dendrolasius) spathepus in Maoershan Natural Reserve, Guangxi, is diagnosed, described and illustrated. The discovery represents the first record of the genus in South China.     

Distribution of cellulosic wall in the anthers of Arabidopsis during microsporogenesis

Key message

Cellulose-specific staining revealed that tapetal cells and microsporocytes lose cellulosic walls before the onset of meiosis. Cellulosic wall degradation in microsporocytes might be independent of tapetal cells (or TPD1).

Abstract

Some cell types in a variety of angiosperms have been reported to lack cell walls. Here, we report that the tapetal cells of the anther of Arabidopsis thaliana did not appear to have a cellulosic wall based on staining with Calcofluor and Renaissance 2200. During sporogenous cell formation, cellulosic wall was present in all anther tissues. However, before meiosis it was almost absent on the tapetal cells and on the microsporocytes. In a sporocyteless/nozzle (spl/nzz) mutant, which lacks several components (microsporocytes, tapetum, middle layer and endothecium), cellulosic wall was detected in all anther cells. In another mutant, tapetum determinant1 (tpd1), which lacks tapetum and has more microsporocytes, cellulosic wall was almost absent on the microsporocytes before meiosis, similar to the wild type. These results suggest that the tapetum cells and microsporocytes lose cellulosic walls during microsporocyte formation, and that cell wall degradation occurs downstream of SPL/NZZ and is independent of TPD1.