Body musculature of Beauchampiella eudactylota (Gosse, 1886) (Rotifera: Euchlanidae) with additional new data on its trophi and overall morphology

This study presents the results of confocal laser scanning microscopy and fluorescence‐labelled phalloidin used to visualize the system of body musculature in Beauchampiella eudactylota. Moreover, the poorly known trophi of B. eudactylota are described based on scanning electron microscopy. In total, four paired longitudinal muscles (musculi longitudinales I–IV) and three circular muscles (musculi circulares I–III) were identified. Among these are the musculus longitudinalis ventralis, the musculus longitudinalis dorsalis and the musculus circumpedalis as documented in previous studies for other rotifer species. Compared to other species, B. eudactylota is characterized by the low number of lateral longitudinal muscles and the absence of some longitudinal muscles (musculi longitudinales capitum) and circular muscles (corona sphincter, musculus pars coronalis). Moreover, scanning electron microscopic data on the trophi of B. eudactylota reveal a number of striking similarities to the trophi in some species of Epiphanidae. This suggests that either (1) these similarities represent plesiomorphic characters present both in Epiphanidae and B. eudactylota or (2) they are synapomorphic features of B. eudactylota and some species of Epiphanidae, which would question the monophyly of Euchlanidae.     

The musculature of Squatinella rostrum (Milne, 1886) (Rotifera: Lepadellidae) as revealed by confocal laser scanning microscopy with additional new data on its trophi and overall morphology

Wilts, E.F., Wulfken, D., Ahlrichs, W.H. and Martínez Arbizu, P. 2012. The musculature of Squatinella rostrum (Milne, 1886) (Rotifera: Lepadellidae) as revealed by confocal laser scanning microscopy with additional new data on its trophi and overall morphology.—Acta Zoologica (Stockholm) 93 : 14–27. The monogonont rotifer Squatinella rostrum was investigated with light, scanning electron and confocal laser scanning microscopy to reveal new morphological data on its inner and outer anatomy. In total, the visualized somatic musculature displays five paired longitudinal muscles (musculi longitudinales I–V) and nine circular muscles (musculi circulares I–IX). Compared to other species, S. rostrum is characterized by the absence of several longitudinal and circular muscles (e.g. musculus longitudinalis capitis, corona sphincter and pars coronalis). A reconstruction of the mastax musculature revealed a total number of seven paired and two unpaired mastax muscles. Possibly homologous somatic and mastax muscles in other, thus far investigated rotifers are discussed. Moreover, we provide a phylogenetic evaluation of the revealed morphological characters and suggest possible autapomorphic characters supporting Squatinella and Lepadellidae. Finally, we refer to some striking similarities in the morphology, ecology and way of movement of Squatinella and Bryceella that may indicate a closer relationship of both taxa.     

The somatic musculature of Bryceella stylata (Milne, 1886) (Rotifera: Proalidae) as revealed by confocal laser scanning microscopy with additional new data on its trophi and overall morphology

The monogonont rotifer Bryceella stylata was investigated with light, electron and confocal laser scanning (CLSM) microscopy to provide detailed insights into its anatomy and new information for future phylogenetic analyses of the group. Results from CLSM and phalloidin staining revealed a total of six paired longitudinal muscles (musculi longitudinales I-VI) and eight circular muscles (musculi circulares I-VIII) as well a complex network of mostly fine visceral muscles. In comparison with other rotifer species that have been investigated so far, B. stylata shares the presence of the circular and longitudinal muscles: musculus longitudinalis ventralis, musculus longitudinalis lateralis inferior, musculus longitudinalis dorsalis, musculus longitudinalis capitis and musculus circumpedalis. However, the species lacks lateral and dorsolateral longitudinal muscles and some circular muscles (e.g., corona sphincter, musculus pars coronalis). With light and electron microscopy, we were able to document the precise number of pseudosegments and the arrangement of the chambers comprising the trophi elements. Furthermore, our observations revealed several new morphological characteristics, including a shield-like epidermal projection covering the dorsal antenna, an epidermal projection restricting the corona caudally and an unpaired hypopharynx with distinct shovel-like structures.     

Body musculature of Stylochaeta scirtetica Brunson, 1950 and Dasydytes (Setodytes) tongiorgii (Balsamo, 1982) (Gastrotricha: Dasydytidae): A functional approach

Species of the freshwater gastrotrich taxon Dasydytidae show a set of conspicuous structural and behavioural adaptations to a semi-planktonic life. Conspicuously, most dasydytids have several groups of strong, moveable spines that can actively be abducted to perform saltatory movements, change the overall direction of locomotion, or enable the animals to rest in a defensive position. So far, there are only vague ideas of how these spine movements are achieved in dasydytid species. In order to gain insight into the possible morpho-functional coupling of body musculature and motile spines, we have carried out a study targeting the muscular system in two species of Dasydytidae by means of phalloidin staining and confocal laser scanning microscopy.

For spine movements in both species studied, Stylochaeta scirtetica and Dasydytes (Setodytes) tongiorgii, we have identified an antagonistic system of segmented longitudinal and oblique somatic muscle pairs. In both species, contraction of the musculi obliqua abduct the paired groups of ventro-lateral spines; contraction of the segments of musculi laterales causes their adduction.

A comparison of the muscular system of the studied species to that of other gastrotrichs reveals several homologous muscle pairs, visceral as well as somatic, that might be features of the stem species of a clade comprising all Paucitubulatina exclusive of Xenotrichulidae. The pairs of oblique somatic muscles are most probably an autapomorphy of Dasydytidae.     

The formation of syncytia within the visceral musculature of the Drosophila midgut is dependent on duf, sns and mbc.

The visceral musculature of the Drosophila midgut consists of an inner layer of circular and an outer layer of longitudinal muscles. Here, we show that the circular muscles are organised as binucleate syncytia that persist through metamorphosis. At stage 11, prior to the onset of the fusion processes, we detected two classes of myoblasts within the visceral trunk mesoderm. One class expresses the founder-cell marker rP298-LacZ in a one- to two-cells-wide strip along the ventralmost part of the visceral mesoderm, whereas the adjacent two to three cell rows are characterised by the expression of Sticks-and-stones (SNS). During the process of cell fusion at stage 12 SNS expression decreases within the newly formed syncytia that spread out dorsally over the midgut. At both margins of the visceral band several cells remain unfused and continue to express SNS. Additional rP298-LacZ-expressing cells arise from the posterior tip of the mesoderm, migrate anteriorly and eventually fuse with the remaining SNS-expressing cells, generating the longitudinal muscles. Thus, although previous studies proposed a separate primordium for the longitudinal musculature located at the posteriormost part of the mesoderm anlage, our cell lineage analyses as well as our morphological observations reveal that a second population of cells originates from the trunk mesoderm. Mutations of genes that are involved in somatic myoblast fusion, such as sns, dumbfounded (duf) or myoblast city (mbc), also cause severe defects within the visceral musculature. The circular muscles are highly unorganised while the longitudinal muscles are almost absent. Thus the fusion process seems to be essential for a proper visceral myogenesis. Our results provide strong evidence that the founder-cell hypothesis also applies to visceral myogenesis, employing the same genetic components as are used in the somatic myoblast fusion processes.     

Histopathology and cellular response in Enteromyxum leei (Myxozoa) infections of Diplodus puntazzo (Teleostei)

Enteromyxum leei is an intestinal parasite responsible for serious outbreaks in Mediterranean sharpsnout sea bream Diplodus puntazzo. E. leei infection was experimentally transmitted to healthy D. puntazzo (R) by cohabitation with infected donor fish. Haematological changes and histopathological damage were evaluated in relation to the course of infection. The prevalence of infection in R fish was 100% from day 10 post-exposure (p.e.) onwards, and the infection intensity and histopathological damage increased progressively. Different developmental stages were found in the infected intestines, including proliferative (stages 1–3) and sporogonic (stages 4 and 5) stages. Intestinal damage consisted of vacuolation, necrosis, detachment and sloughing of epithelium, and was correlated with the progression of the infection and with the development of the parasite. Sporogonic stages appeared from day 20 p.e. onwards. Initially, D. puntazzo seems to counteract the infection through the increase in leucocyte numbers, respiratory burst activity, haematopoietic activity and MMC. Two types of eosinophilic granular cells (EGC1 and EGC2) were detected in the intestinal epithelium and lamina propria. EGC1 numbers decreased with the progression of infection, whereas an increase in EGC2 occurred, mainly in the lamina propria. The involvement of the cellular immunity in the response of D. puntazzo to E. leei was demonstrated. The depletion of this response at a certain point of the infection could contribute to the high virulence of this myxozoan in this fish species.     

Genetic evidence against a morphologically suggestive conspecificity of Dermacentor reticulatus and D. marginatus (Acari: Ixodidae)

Dermacentor reticulatus and D. marginatus exhibit overlapping phenotypes. The possibility of conspecificity was investigated on the nucleotide level by comparing DNA sequences of the second internal transcribed spacer (ITS 2) of the rDNA gene. The inter-specific polymorphism was more than 20-times greater than the intra-specific polymorphism of 3 D. reticulatus strains of different geographic origins. Furthermore, the degree of polymorphisms between D. reticulatus and D. marginatus was found to be of the same order of magnitude as that between D. andersoni and D. variabilis, for which separate species status is accepted. These genomic findings do not support a possible conspecificity of D. reticulatus and D. marginatus.     

Earthworms (Clitellata, Acanthodrilidae) of the mountains of Eastern Jamaica

Fourteen species new to science are described from material collected at several sites in the Blue Mountains and the John Crow Mountains of eastern Jamaica, doubling the known endemic Jamaican earthworm fauna. New data on Dichogaster montecyanensis (Sims) are provided. All species are placed in the genus Dichogaster Beddard, which is here treated sensu lato, i.e. including Eutrigaster Cognetti. Eight of the new species have lost the posterior pair of prostates and the seminal grooves of the male field. These are D. bromeliocola, D. crossleyi, D. davidi, D. garciai, D. harperi, D. haruvi, D. hendrixi, and D. johnsoni. D. sydneyi n. sp. has independently lost the posterior prostates but not the seminal grooves. The new species D. altissima and D. manleyi have the conventional dichogastrine prostatic battery and male field characteristics. Three species described here, D. farri, D. garrawayi, and D. marleyi, all have a third pair of prostates in the 20th segment, no seminal grooves, dorsal paired intestinal caeca in segment lxv, and lack penial setae.     

Distribution and habitat preferences of species within the genus Elaphoidella Chappuis, 1929 (Crustacea: Copepoda: Harpacticoida) in Slovenia

Twelve species of the harpacticoid genus Elaphoidella, most of them exclusively groundwater species, have been recorded in Slovenia (SE Europe). Their distribution and ecology are reviewed with the aim of evaluating distribution patterns, species preferences for groundwater habitats, ecological preferences and interactions with other copepod species at regional scale. Data on Elaphoidella species were obtained partly from the existing literature and partly from the author's (AB) own sampling campaigns carried out together with his co-workers. During the rich history of collecting copepods in Slovenia (from the 1920s to present), Elaphoidella species were recorded at 78 sampling sites altogether. The majority of collecting was conducted in the southern (Dinaric region) and north-western (Alpine region) Slovenia. The most intensively sampled habitats were porous aquifers of alluvial plains, springs in the karstic unsaturated zone and percolation water in caves. The highest species richness of Elaphoidella was recorded in the southern Slovenia, where 10 species were found. The strictly “Dinaric” species are E. charon, E. franci, E. karstica, E. stammeri, E. sp. 1 and E. sp. 2, while E. phreatica and E. bidens were found exclusively in the north-western Slovenia. From the latest data on the copepod distributions (2002–2004), where the environmental characteristics of sampling sites were also measured, the relationship between selected environmental characteristics of the habitats and the presence of Elaphoidella species was analysed. The distribution of Elaphoidella species in Slovenia was found to be related with the region, habitat type, altitude, conductivity and pH of the water.     

Chloroplast DNA and the determination of species status in the Disa tripetaloides complex (Orchidaceae), and its relationships to three species Racemosae, section Disa

Disa cardinalis and three populations within the D. tripetaloides species complex contain variation in their chloroplast DNA (cpDNA) variability. All four taxa possessed unique cpDNAs and sequence divergence values ranged from 0.34 to 1.03%. A phylogeny of these genomes was reconstructed, along with the genomes of three other species, D. racemosa, D. uniflora and D. venosa, all of which are also section Disa and series RAcemosae, to determine the relationship of these closely related species to the D. tripetaloides complex. A phylogeny of the taxa using morphological data was also reconstructed. Outgroup comparison was made with D. sagittalis, a member of section Coryphaea. Although the molecular and morphological data were not completely congruent, both data types revealed D. cardinalis, rather than D. tripetaloides ssp. aurata, to be more closely allied with D. tripetaloides ssp. tripetaloides, suggesting that D. tripetaloides ssp. aurata should be elevated to species rank. Additionally, the high sequence divergence observed between the Natal and Cape populations, coupled with their geographical isolation and alternate flowering seasons, suggests that these two D. tripetaloides ssp. tripetaloides populations may, in fact, be more appropriately ranked as subspecies.     

Evolution of body-wall musculature in the Platyhelminthes (Acoelomorpha, Catenulida, Rhabditophora)

In an effort to understand the phylogeny of the Platyhelminthes, the patterns of body-wall musculature of flatworms were studied using fluorescence microscopy and Alexa-488-labeled phalloidin. Species of the Catenulida have a simple orthogonal gridwork of longitudinal and circular muscles. Members of the Rhabditophora have the same gridwork of musculature, but also have diagonal muscles over their entire body. Although a few species of Acoelomorpha possessed a simple orthogonal grid of musculature, most species typically have distinctly different patterns of dorsal and ventral body-wall musculature that include sets of longitudinal, circular, U-shaped, and several kinds of diagonal muscles. Several distinct patterns of musculature were identified, including 8 patterns in 11 families of acoels. These patterns have proven to be useful in clarifying the phylogeny of the Acoelomorpha, particularly with regard to the higher acoels. Patterns of musculature as well as other morphological characters are used here for revisions of acoel systematics, including the return of Eumecynostomum sanguineum (Mecynostomidae) to the genus Aphanostoma (Convolutidae), the revision of the family Childiidae, and the formation of a new family, Actinoposthiidae.     

Phalloidin-rhodamine preparations of Macrostomum hystricinum marinum (Plathelminthes): morphology and postembryonic development of the musculature

Summary A whole-mount fluorescence technique using rhodamine-labeled phalloidin was used to demonstrate for the first time the whole muscle system of a free-living plathelminth, Macrostomum hystricinum marinum. As expected, the body-wall musculature consisted of circular, longitudinal, and diagonal fibers over the trunk. Also distinct were the musculature of the gut and of the mouth and pharynx (circular, longitudinal, and radial). Dorsoventral fibers where restricted in this species to the head and tail regions. Circular muscle fibers in the body wall were often grouped into bands of up to four parallel strands. Surprisingly, diagonal fibers formed two distinct sets, one dorsal and one ventral. Certain diagonal muscle fibers entered the wall of the mouth and were continuous with some longitudinal muscles of the pharynx. Dorsoventral fibers in the rostrum occurred partly in regularly spaced pairs, a fact not known for free-living Plathelminthes. All muscle fibers appeared to be mononucleated. During postembryonic development, the number of circular muscle fibers can be estimated to increase by a factor of 3.5 and that of longitudinal muscles by a factor of 2. Apparently as many as 700–800 circular muscle cells must be added in the region of the gut alone during postembryonic development. Stem cells (neoblasts), identified by TEM in the caudalmost region of the gut, lie along the lateral nerve cords. In the same body region most perikarya of circular muscle cells occurred in a similar position. This suggests that the nucleus-containing part of the cell remains in the position where differentiation starts.     

Bt水稻秸秆还田对赤子爱胜蚓生长发育和生殖的影响

Bt蛋白能通过转Bt基因作物的秸秆还田进入土壤,进而可能会对土壤动物如蚯蚓的生长发育和生殖造成影响.为评估Bt水稻对赤子爱胜蚓的影响,本文模拟秸秆还田,在土壤中添加2.5%、5%、7.5%和10% Bt水稻(b2B138)及其同源水稻(安丰A)秸秆,分别在饲养赤子爱胜蚓7、15、30、45、60、75和90 d后观测蚯蚓的存活率、相对生长率和生殖情况,以及秸秆土壤混合物和蚯蚓体内的Cry1Ab蛋白含量.结果表明:较高还田量(7.5%和10%)Bt水稻秸秆处理对赤子爱胜蚓存活率有抑制作用;Bt水稻秸秆还田对赤子爱胜蚓的相对生长率没有不利影响;还田量为5%、7.5%和10%时,Bt水稻秸秆还田能促进蚯蚓的生殖.酶联免疫吸附测定法(ELISA)结果表明: 在Bt水稻土壤混合物中,蚯蚓体内均能检测到Cry1Ab蛋白,且前者随着时间延长而显著减少.因此,还田量为2.5%和5%时,Bt水稻秸秆还田释放的Cry1Ab蛋白对赤子爱胜蚓的生长发育和生殖没有不利影响.     

Musculature of an illoricate predatory rotifer Asplanchnopus multiceps as revealed by phalloidin fluorescence and confocal microscopy

The pattern of muscles in the actively swimming predatory rotifer Asplanchnopus multiceps is revealed by staining with tetramethyl-rhodamine isothiocyanate (TRITC)-labelled phalloidin and confocal scanning laser microscopy (CSLM). The major components of the musculature are: prominent semicircular muscles of the corona; paired lateral, dorsal and ventral retractors in the trunk; a network of six seemingly complete circular muscles and anastomosing longitudinal muscles in the trunk; two short foot retractors, originating from a transverse muscle in the lower third of the trunk. The sphincter of the corona marks the boundary between the head and the trunk. The muscular patterns in rotifers with different lifestyles differ clearly, therefore, the muscular patterns seem to be determined by the mode of locomotion and feeding behaviour.     

Chemical composition of essential oils of seven species of Eugenia from Monteverde, Costa Rica

The leaf essential oils of seven species of Eugenia from Monteverde, Costa Rica (Eugenia austin-smithii, Eugenia cartagensis, Eugenia haberi, Eugenia monteverdensis, Eugenia zuchowskiae, Eugenia sp. A aff. haberi, and Eugenia sp. B aff. oerstediana) have been obtained by hydrodistillation and analyzed by GC–MS. The seven species were compared to determine the similarities and differences among their volatile chemical compositions. The major component in each of the seven species was as follows: E. austin-smithii and E. cartagensis was trans-2-hexenal, E. haberi and E. zuchowskiae was -pinene, E. monteverdensis was linalool, Eugenia sp. A was zingiberene, and Eugenia sp. B was 1,8-cineole. The following six components were present in all seven species: -copaene, β-caryophyllene, -humulene, δ-cadinene, trans-nerolidol, and torreyol. The complex array and differing abundances of these compounds among the Eugenia species studied suggest that they may provide useful characters in understanding the phylogenetic relationships among closely related species.     

Functional morphology of the muscles in Philodina sp. (Rotifera: Bdelloidea)

Whole-mounts of Philodina sp., a bdelloid rotifer, were stained with fluorescent-labeled phalloidin to visualize the musculature. Several different muscle types were identified including incomplete circular bands, coronal retractors and foot retractors. Based on the position of the larger muscle bands in the body wall, their function during creeping locomotion and tun formation was inferred. Bdelloid creeping begins with the contraction of incomplete circular muscle bands against the hydrostatic pseudocoel, resulting in an anterior elongation of the body. One or more sets of ventral longitudinal muscles then contract bringing the rostrum into contact with the substrate, where it presumably attaches via adhesive glands. Different sets of ventral longitudinal muscles, foot and trunk retractors, function to pull the body forward. These same longitudinal muscle sets are also used in `tun' formation, in which the head and foot are withdrawn into the body. Three sets of longitudinal muscles supply the head region (anterior head segments) and function in withdrawal of the corona and rostrum. Two additional pairs of longitudinal muscles function to retract the anterior trunk segments immediately behind the head, and approximately five sets of longitudinal retractors are involved in the withdrawal of the foot and posterior toes. To achieve a greater understanding of rotifer behavior, it is important to elucidate the structural complexity of body wall muscles in rotifers. The utility of fluorescently-labeled phalloidin for the visualization of these muscles is discussed and placed in the context of rotifer functional morphology.     

Population dynamics of the harmful diatom Eucampia zodiacus Ehrenberg causing bleachings of Porphyra thalli in aquaculture in Harima-Nada, the Seto Inland Sea, Japan

The diatom Eucampia zodiacus Ehrenberg is one of the harmful diatom species which indirectly cause bleachings of Nori (Porphyra thalli) in aquaculture through competitive utilizing of nutrients (especially nitrogen) and resultant nutrient depletion in water columns during the bloom events. The seasonal changes in environmental factors, cell density and cell size of E. zodiacus were investigated for 4 years (April 2002–December 2005) to understand the population ecology of this diatom in Harima-Nada, the eastern part of the Seto Inland Sea, Japan. Vegetative cells of E. zodiacus were usually detected year-round. Total cell densities of E. zodiacus annually peaked from mid-February to early April, and high cell densities were observed in the whole water columns during the bloom-period. Nutrient concentrations decreased with the increase of cell density of E. zodiacus, and low nutrients concentrations continued throughout the E. zodiacus bloom-period. The average cell size (length of apical axis) of E. zodiacus populations ranged from 10.8 μm to 81.2 μm, and the restoration of cell size occurred once in autumn every year just after reaching the minimum cell size. In addition, its great seasonal regularity was confirmed by the decrease and restoration of its cell size through 4-year study period. Temperature and nutrients were suitable in autumn for the growth of E. zodiacus, its blooms never occur in that season. These results strongly suggest that E. zodiacus did not have a resting stage, and it spends autumn for size restoration and starts to bloom thereafter in Harima-Nada in winter and spring, causing fishery damage to Nori aquaculture by resulting nutrient deprivation.     

Efficient plant regeneration from seedling explants of two commercially important temperate eucalypt species–Eucalyptus nitens and E. globulus

A reliable and reproducible method for plant regeneration in vitro of two important temperate eucalypts, Eucalyptus nitens and E. globulus, has been developed which utilises seedling explants. Highly regenerative callus was obtained from individual cotyledon and hypocotyledon explants of both species following cultivation on Murashige and Skoog’s (MS) basal nutrient medium supplemented with 30 g l⁻¹ sucrose, 5–10% (v/v) coconut water, 0.8% agar, 1 mg l⁻¹ -naphthalene-acetic acid (NAA) and 0.5 mg l⁻¹ N⁶ benzylaminopurine (BAP). Shoot differentiation was observed 7–8 weeks after transfer of callus onto regeneration medium containing 0.5 mg l⁻¹ NAA and 1 mg l⁻¹ BAP. In a few instances, direct shoot regeneration occurred without an intervening callus phase in both species. The frequency of plant regeneration was higher for callus derived from hypocotyl segments (30–35%) compared to cotyledonary explants (20–25%) though the average number of shoots per cotyledonary explant was generally higher than for hypocotyl explants. Somatic embryos were observed occasionally in E. nitens, arising from the surface of organogenic callus. Organised structures closely resembling somatic embryos were also observed in E. globulus. Regenerated shoots (30–40%) of both species could be rooted in modified MS media containing indole-3-butyric acid (IBA) and plantlets were successfully transferred to soil.     

The sex-peptide gene (Acp70A) is duplicated in Drosophila subobscura

A 3.1-kb region of Drosophila subobscura homologous to the Acp70A region of D. melanogaster, which contains the sex-peptide gene, was cloned and sequenced. This region contains an approximately 600-bp duplication that includes the sex-peptide and its 5′ and 3′ flanking regions. The preproteins are 54 and 56 amino acids long, respectively (as compared to 55 amino acids in D. melanogaster), and each includes a 19-amino-acid-long signal peptide. The C-terminal part of the mature peptide is highly conserved between D. melanogaster and the two copies of D. subobscura. In this species, both copies of the gene are transcribed and, like in D. melanogaster, only expressed in males. The duplicated region includes 300 bp upstream of the gene that would therefore seem sufficient for their expression in males. This region presents at its 5′ end a stretch 93-bp that has a high similarity with the corresponding region of D. melanogaster and could be part of a still unidentified regulatory element of these genes.