Chemotactically-induced redistribution of CD43 as related to polarity and locomotion of human polymorphonuclear leucocytes

Leukocyte motility involves pseudopods extension at the leading edge and uropod contraction at the cell rear. Previous studies have shown that the glycoprotein CD43 redistributes to the uropod, when the cells develop polarity and locomotion. The present study addresses the question whether the accumulation of specific membrane molecules, such as CD43 at the contracted uropod precedes or follows development of polarity and locomotion. PMNs were labeled with fluorescent anti-CD43 antibodies and guided to polarize in the direction of a chemoattractant-containing micropipette or, once polarized, they were forced to reverse polarity and movement direction by placing the micropipette behind the uropod. This chemotactically-induced reversal of polarity was used as an efficient tool to analyse the sequence of events. CD43, but not another abundant surface glycoprotein CD45, was concentrated at the uropod. This documents that CD43 redistribution is a selective phenomenon. During reversal of polarity and of locomotion direction, the geometric center of the cell clearly changed direction earlier than the center of anti-CD43 fluorescence intensity. Thus, CD43 redistribution to the new uropod follows rather than precedes reversal of polarity, suggesting that CD43 redistribution is a consequence rather than a prerequisite for polarity and locomotion. PMNs making a U-turn maintained the pre-existing polarity and CD43 remained concentrated at the uropod, even when the front was moving in the opposite direction. Our data show that anterior pseudopod formation, rather than capping of CD43 at the uropod or the position of the uropod determines the direction of locomotion.     

Three new species of Hyalella from Chile (Crustacea: Amphipoda: Hyalellidae)

Hyalella is the only epigean freshwater amphipod present in Chile . H. chiloensis, H. costera and H. kochi are here described and illustrated. H. kochi is distributed in highland areas of the Andes in northern Chile; it is characterized by a short ramus on uropod 3 and a hammer-shaped gnathopod 1. H. costera and H. chiloensis are present in lowland areas, the latter restricted to the southern part of the country. These two species have a long ramus on uropod 3, but they differ in the shape and length of the palp on maxilla 1, the setation of peraeopods 3, 4, and telson. The presence in Chile of H. fossamancinii Cavalieri, 1959 is also reported here.     

Doxomysis algoaensis, a new mysid species (Crustacea: Mysidacea) from Algoa Bay (South Africa)

Doxomysis algoaensis sp.nov. is described from Algoa Bay, South Africa where it is common in nearshore marine waters just beyond the breaker line. D. algoaensis sp.nov. is morphologically similar to D. australiensis, but can readily be distinguished by the shape and armature of the telson and the length of the exopod of the fourth male pleopod. The apical cleft is one fifth the telson length in the former species and one third the length in D. australiensis. The telson apex on each side of the cleft is also armed with five and four stout spines in the two species, respectively. In D. australiensis, the exopod of the fourth male pleopod is almost three times the length of the endopod; in D. algoaensis sp.nov., the exopod is only slightly longer than the endopod. Other distinctive features of D. algoaensis sp.nov. include the maxillary palp, which is only slightly broader than long and the greater number of spines on the endopod of the uropod.     

Gating behaviors of a voltage-dependent and Ca2+-activated cation channel of yeast vacuolar membrane incorporated into planar lipid bilayer

Summary A voltage-dependent and Ca²⁺-activated cation channel found in the vacuolar membrane of the yeast,Saccharomyces cerevisiae, was incorporated into planar lipid bilayer and its gating characteristics were studied at the macroscopic and single-channel levels. The open-channel probability at steady state, which was estimated by the macroscopic current measurement, gave a maximum value at –10 mV and decreased in a graded fashion as the voltage became more positive or more negative. The steady-state voltage dependence was explained by assuming two independent gates, which had different rate constants and opposite voltage dependence. The fast-responding gate opened when the voltage of thecis side (the side to which the vesicles were added) was made more negative and the slow-responding gate behaved in the opposite direction. Relatively high concentrations of Ca²⁺, about 1mm, were required on thecis side for opening the slow gate in a voltage-dependent manner. DIDS increased the open-channel probability of the fast gate when added to thecis side, but was ineffective on the slow gate.     

Ethylene evolution changes in the stems of<Emphasis Type="Italic"> Metasequoia glyptostroboides</Emphasis> and<Emphasis Type="Italic"> Aesculus turbinata</Emphasis> seedlings in relation to gravity-induced reaction wood formation

Two-year-old Metasequoia glyptostroboides and 3-month-old Aesculus turbinata seedlings were tilted at a 45° angle to induce compression wood formation on the lower side of the former species and tension wood on the upper side of the latter. Two weeks later, the seedlings were tilted in an opposite direction at 45° so that the upper and lower sides changed to each other. This reverse tilting was kept for 7 weeks for M. glyptostroboides and 6 weeks for A. turbinata. The seedlings were sampled and analyzed at intervals throughout each experimental period so that an ethylene evolution kinetic was monitored. Ethylene evolution from the cambial region of the upper and lower sides of tilted stems was measured separately by gas chromatography with a flame ionization detector. Xylem production expressed as wood area during each experimental period was microscopically determined. In both tilting and reverse tilting periods, the rates of ethylene evolution from the lower side of M. glyptostroboides and the upper side of A. turbinata, where xylem production was accelerated and compression or tension wood formation was induced, had increased to high levels, whereas those from the opposite sides had either remained low (in tilting period) or rapidly recovered to low levels (in reverse tilting period). The cambial activity quantified by wood formation, including reaction wood, in both species showed the same tendency as ethylene evolution. The stem side with vigorous ethylene evolution, xylem development and reaction wood formation reversed with the reversal of tilting orientation. The roles of accelerated ethylene evolution in reaction wood formation in the tilted seedlings of gymnosperm and angiosperm trees are compared and discussed.This work was presented at the 5th Pacific Region Wood Anatomy Conference, Yogyakarta, Indonesia, 9–14 September 2002     

Habrobathynella nagarjunai n. sp., the second representative of Bathynellacea (Crustacea, Syncarida) from groundwaters of South India

A new species of the genus Habrobathynella Schminke, 1973, i.e. H. nagarjunai n.sp., is described from the groundwater of the Nagarjuna University campus near Guntur town, South India. One of the principal criteria in the original definition of Habrobathynella is amended to accommodate the new species. H. nagarjunai n.sp. differs from its three congeners, i.e. H. milloti (Delamare & Paulian, 1954), H. jeanneli (Delamare & Paulian, 1954) from Madagascar, and H. schminkei Reddy, 2002 from India, in several essential morphological details: the sympodite of uropod bears 8–10 similar spines; the apophysis on segment 4 of the antennule is short; of the two setae on the exopodite of uropod, one is apical and the other subapical in position; the basal segment of maxilla has three unequal setae; the male thoracopod VIII is relatively elongate. H. nagarjunai n. sp. is the second representative of the groundwater (eustygobiont) Bathynellacea in South Asia. Furthermore, a key to the identification of Habrobathynella spp. is given.     

Ultrastructure of the flagellar apparatus inPyramimonas octopus (Prasinophyceae)

Summary While green algae usually lack one of the outer dynein arms in the axoneme, flagella of the octoflagellated prasinophytePyramimonas octopus possess dynein arms on all peripheral doublets. The outer dynein arm on doublet no. 1 is modified, and additional structures are associated with doublets no. 2 and 6. The flagellar scales are asymmetrically arranged. Thus the two rows of thick flagellar hairscales are displaced towards doublet no. 6,i.e., in the direction of the effective stroke of each flagellum. The underlayer of small scales includes two nearly opposite double rows scales, arranged in the longitudinal direction of the flagellum. The hairscales emerge from these rows. The double rows are separated on one side by 9, on the other by 11 rows of helically arranged scales. The central pair of microtubules twists, but the axoneme itself (represented by the 9 peripheral doublets), does not seem to rotate. The flagella are arranged in two groups, showing modified 180° rotational symmetry. The effective strokes of the two central flagella are exactly opposite, while the other flagella beat in six intermediate directions.     

Reassessment of the isopod crustacean Aega deshaysiana (Milne Edwards, 1840) (Cymothoida: Aegidae): a world-wide complex of 21 species

Aega deshaysiana (Milne Edwards, 1840) and A. antillensis Schioedte & Meinert, 1879, have long been confounded, with all records eventually becoming regarded as belonging to one globally distributed species, namely A. deshaysiana. These two species are redescribed and differentiated, with A. schioedteana Bovallius, 1885 remaining in synonymy with A. deshaysiana. Aega deshaysiana occurs only in the eastern North Atlantic and Mediterranean, while A. antillensis is known only from the Caribbean and Gulf of Mexico. A further two named species are redescribed: A. excisa Richardson, 1910, previously placed in synonymy with A. deshaysiana, and A. magnifica (Dana, 1852). A neotype is designated for A. magnifica. This ‘complex’ or group of Aega species is distinguished from the others by their large eyes, which are usually medially united and occupy most of the head, their large adult size (20–60 mm), a posteriorly acute and defined pleotelson apex, and the uropod rami not extending posteriorly beyond the pleotelson, with exopod held at an oblique angle to the endopod and deeply notched endopod lateral margin. The group is not necessarily monophyletic, as there is a gradation in the depth of the uropod notch from deep to scarcely evident, and in eye size from entirely occupying the head to just separate (though the eyes are always large). Twelve new species in the group are described. All species are considered to be micropredators of fishes and elasmobranches, although prey records are few and unreliable owing to the readiness of these isopods to detach. Species of the group have been recorded from depths varying between 10 m and 600 m and occasionally deeper. Several have extensive distributions ranging from the Southern Ocean to tropical waters. The group is represented in all oceans. © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society, 2004, 142 , 135–232.     

The terminus of the Escherichia coli chromosome is flanked by several polar polar replication pause sites

Replication of two small ‘constrained’ regions of the Escherichia coli chromosome, one bordered by replication terminator T1 and the other by T2, displays normal velocity in the normal direction whereas it is much slower in the opposite direction (de Massy et al., 1987). The presence of multiple polar terminators has been investigated, using a bacteriophage λ derivative which provides a replication origin movable to predetermined loci and inducible on demand. The amount of DNA made from this induced origin was determined by in vivo labelling and hybridization to probes of the surrounding region. A redundancy of terminator-like sequences, or pause sites, has been disclosed. So far, two polar pause sites, in the same orientation and separated by 50 or 80 kb, have been localized on each side of the terminus region. The results are discussed in relation to previously observations indicating that these regions are refractory to genomic inversions.     

Seedling morphology ofLespedeza (Leguminosae)

Seedling morphology was studied in 22 species ofLespedeza, of which six belong to subgenusMacroles-pedeza and 16 to subgenusLespedeza. Two seedling types were recognized: 1) those with opposite leaves at the first node; 2) those having the first and subsequent leaves alternate. The two types are distinguished in the number of leaf primordia in the plumule of the seed: the opposite type has two leaf primordia, but the alternate type has only one primordium. Most species exhibited one of the two types, but rarely both types were observed in several species. In species having two types, one type always far outnumbers the other. The opposite type was common in Asian species, while the alternate type was common in North American ones. Because seedlings are of the opposite type inKummerowia which is the most closely related genus withLespdeza, the alternate type is considered to be apomorphic inLespedeza. The apomorphic seedling morphology is, there-fore, dominantly occurred in North American species ofLespedeza. This fact may be an evidence which suggests a monophyletic origin for North American species from an Asian ancesfor.     

Oviposition by Aedes aegypti and Aedes albopictus: Influence of congeners and of oviposition site characteristics

We investigated the oviposition behavior of Ae. aegypti and Ae. albopictus. In particular we examined whether small‐scale site characteristics and the presence of conspecifics or congeners altered oviposition by these mosquitoes. Various combinations of females of the two species were allowed to oviposit inside cages among either vegetation (potted plants) or structural components (wood and concrete blocks). Numbers of eggs deposited per female were compared between species, sides, and treatments. Most significant differences between treatments and species involved differences between single species and mixed species treatments. Ae. aegypti deposited more eggs/female in the vegetation side than in the structure side whereas the opposite pattern was evident for Ae. albopictus. Ae. aegypti females had higher frequency of skip oviposition than Ae. albopictus. An average of 63% of the containers in the two‐species treatments contained eggs of both species, with more frequent joint occurrences observed in the treatment with three females of each species than in the treatments with one of each. Our results point to the existence of various interactions between gravid Ae. aegypti and Ae. albopictus females at or near the oviposition sites but further experimental work is necessary to fully characterize the interactions and their specific mechanisms.     

Coordination between the legs and tail during digging and swimming in sand crabs

Rhythmic leg movements and tailflipping are mutually exclusive behaviours in most decapod crustaceans, but sand crabs (Anomura: Hippoidea) combine leg movements with simultaneous tailflipping or uropod beating for both digging and swimming. We examined the coordination between the legs and tail (abdomen and tailfan) of Blepharipoda occidentalis, Lepidopa californica (Albuneidae), and Emerita analoga (Hippidae). When either albuneid swims, the tail cycles at a higher frequency than the legs, and the two rhythms are not coupled. When albuneids begin digging, the tail's frequency drops to that of the legs, and its rhythm becomes phase coupled to the legs. In E. analoga the legs seldom move during swimming by uropod beating. During digging the frequency of the uropods and fourth legs starts at about double that of the second and third legs, but drops to that of the second and third legs as digging progresses. The fourth legs in E. analoga are coupled with the uropods; their outward movement (= power stroke) is concurrent with the uropod return stroke. The familial differences in leg coordination and in the coordination of the legs and tail account for the smooth descent of E. analoga beneath sand compared to the stepwise descent of the albuneids. Accepted: 23 August 1996     

VALVE MORPHOGENESIS AND THE MICROTUBULE CENTER IN THREE SPECIES OF THE DIATOM NITZSCHIA1

The relationship of cell organelles to valve morphogenesis was investigated in three species of Nitzschia. One, N. sigmoidea (Nitzsch) W. Sm., showed consistent ability to generate both nitzschioid and hantzschioid symmetry in daughter cells following cytokinesis; the other two maintained nitzschioid symmetry stably. From previous work with Hantzschia, a certain sequence of events could be anticipated in the cytoplasm. In two significant areas–the behavior of the Microtubule Center (MC) and its microtubule (MT) system, and the central origin of the silicalemma–not only were the results unexpected, but the three species showed fundamental differences among themselves. In N. sigmoidea, the silicalemma (and the future raphe region) arises centrally on the cleavage furrow, and after some lateral expansion, the silicalemmas and their associated organelles move in opposite directions in daughter cells, so that the raphe and the raphe canals end up along the girdle side of the cell as expected. However, the MCs never become associated with their silicalemma, remaining throughout near the girdle bands. In N. sigma (Kütz) W. Sm., the silicalemmas arise centrally and after lateral growth, move in opposite directions to generate nitzschioid symmetry. In this case, the MCs move to the vicinity of but never close to the silicalemmas, and follow them distantly during their lateral movement. In N. tryblionella Hantzsch, the new silicalemmas arise opposite one another, on one side of the daughter cells; each MC soon moves very close to its silicalemma, and remains thus through most of valve morphogenesis. Later, only one silicalemma/MC complex moves laterally, establishing the nitzschioid symmetry in both daughter cells. In all three species, as in Hantzschia, linear arrays of mitochondria aligned along MTs occupy the forming raphe canal, and microfilaments line the outer edge of the expanding silicalemma. The fibulae (the wall struts arching across the raphe canal) in Hantzschia always grow from the valve surface to the girdle surface of the forming valves. In these three Nitzschiae, this invariably happens in only one daughter cell of any pair; in the other, all the fibulae grow from the girdle surface to the valve surface. An explanation of these variations is proposed: that the morphogenetic machinery of Nitzschia and Hantzschia have a common origin, with present Nitzschiae having undergone considerable diversification at the intracellular level, causing the unstable cell symmetry exhibited by several modern species. Perhaps a taxonomic distinction between Hantzschia and Nitzschia lies in whether the morphogenetic machinery associated with valve morphogenesis moves laterally in the same or in opposite directions.     

A new species of Ampelisca (Crustacea, Amphipoda) from NW Iberian Peninsula: Ampelisca troncosoi sp. nov.

A new species of Ampelisca (Crustacea, Amphipoda) is described from samples collected in shallow subtidal fine and very fine sand in the inlet of Baiona (Galicia, NW Iberian Peninsula). Ampelisca troncosoi sp. nov. is closely related to A. brachyceras and A. heterodactyla by having a rostrum between antenna 1 pair and one lateral angle at each side of the head. The new species may be distinguished by the following combination of characters: a distally rounded rostrum between the antenna 1 pair, one laterodorsal pair of corneal lenses, antenna 1 longer than antenna 2 peduncle, antenna 2 never reaching half of the body length, epimeral plates with rounded posterodistal angle, a prominent rounded urosomal carina and two rows of minute spines on the outer rami of the uropod 3.     

Escape trajectories of the rockpool prawn (Palaemon elegans) in response to visual and mechanosensory stimuli

Small crustaceans, such as the rockpool prawn Palaemon elegans Rathke, respond to the approach of predators by executing a version of the crustacean tail-flip response, known as the ‘jack-knife’. We used two types of stimulus to investigate the escape behaviour of P. elegans, specifically the escape trajectories taken by individual prawns. The first stimulus consisted of mechanosensory cues, while the second stimulus included visual and mechanosensory cues. Responses to the two stimulus types differed, with the combined cues from the second stimulus type resulting in escapes over longer distances, and with greater directionality, compared to those following purely mechanosensory stimulation. Altering the direction of approach of the ‘predator’ affected the proportion of escapes that were to the side opposite from the eliciting stimulus and strongly influenced escape trajectories. Such unpredictability in the escape direction of P. elegans may be an example of so-called ‘Protean’ behaviour.     

Morphometric study of the red shrimp Aristeus antennatus in the Eastern Mediterranean

The relative growth of body parts (abdomen, uropod, scaphocerite, telson, rostrum and the third pereiopod) of both sexes of red shrimp Aristeus antennatus was studied in the Greek and Italian Ionian Sea (Eastern Mediterranean), at a depth range from 546 to 1,047 m. Morphometric relationships in the sexes showed similar patterns of relative growth in the two study areas. Although, morphological characters (abdomen, carapace length, pereiopod, rostrum, scaphocerite, telson, uropod and weight) of female were significantly greater than males, in both areas the observed differences between sexes could also attributed to the seasonal mobility pattern of females and to their reproductive activity. A negative allometry of swimming morphological characters (uropod, scaphocerite, telson) and of abdomen (related to the rapid locomotion, reproduction) was found in both sexes and areas. In contrast to this, the growth the third pereiopod (involved in walking ability) in both sexes and areas was isometric. Males showed no correlation of rostrum length with size. Some morphological characters (pereiopod, scaphocerite, uropodal exopodite) were proportionally longer in juvenile females than in adult females, indicating that the allometry differs for this species during its life cycle. A clear increasing trend of females’ size, including all the morphological characters, was shown with decreasing temperature and increasing depth.     

Base Composition Skews, Replication Orientation, and Gene Orientation in 12 Prokaryote Genomes

Variation in GC content, GC skew and AT skew along genomic regions was examined at third codon positions in completely sequenced prokaryotes. Eight out of nine eubacteria studied show GC and AT skews that change sign at the origin of replication. The leading strand in DNA replication is G-T rich at codon position 3 in six eubacteria, but C-T rich in two Mycoplasma species. In M. genitalium the AT and GC skews are symmetrical around the origin and terminus of replication, whereas its GC content variation has been shown to have a centre of symmetry elsewhere in the genome. Borrelia burgdorferi and Treponema pallidum show extraordinary extents of base composition skew correlated with direction of DNA replication. Base composition skews measured at third codon positions probably reflect mutational biases, whereas those measured over all bases in a sequence (or at codon positions 1 and 2) can be strongly affected by protein considerations due to the tendency in some bacteria for genes to be transcribed in the same direction that they are replicated. Consequently in some species the direction of skew for total genomic DNA is opposite to that for codon position 3. Received: 2 February 1998 / Accepted: 15 June 1998     

Speciation history of three closely related oak gall wasps,Andricus mukaigawae,A. kashiwaphilus,and A. pseudoflos (Hymenoptera: Cynipidae) inferred from nuclear and mitochondrial DNA sequences

The Andricus mukaigawae complex of oak gall wasps is composed of cyclically parthenogenetic species: A. mukaigawae and Andricus kashiwaphilus, and a parthenogenetic species, Andricus pseudoflos. The component species differ in life history, host plant, karyotype, and asexual gall shape, although little difference is found in the external morphology of asexual adults. To understand the speciation history of this species complex, DNA sequences of one mitochondrial region and nine nuclear gene regions were investigated. The genetic relationship among the species suggested that a loss of sex occurred after host shift. Unexpectedly, two or three distinct groups in the parthenogenetic species, A. pseudoflos, were revealed by both mitochondrial and nuclear DNA data. Gene flow in nuclear genes from the species not infected by Wolbachia (A. kashiwaphilus) to the species infected by it (A. mukaigawae) was suggested by a method based on coalescent simulations. On the other hand, gene flow in mitochondrial genes was suggested to be in the opposite direction. These findings indicate possible involvement of Wolbachia infection in the speciation process of the A. mukaigawae complex.     

Reproductive system of the genus <Emphasis Type="Italic">Crasiella</Emphasis> (Gastrotricha,Macrodasyida)

Crasiella diplura from Sweden and Crasiella sp. from Italy were studied alive and with transmission electron microscopy (TEM). The two species are simultaneous hermaphrodites and share the same reproductive system lay-out: paired ovaries extend along the posterior part of the intestine and join mid-dorsally, while bilateral, club-shaped testes lie at the sides of the anterior gut, extending as deferentia that fuse on the mid-ventral plane and open into a single pore; gametes mature in a caudocephalic and centripetal direction. The bulky, sac-like, frontal organ is lined by a simple epithelium and lies dorsolaterally to the intestine, on the left side of the body. The spindle-shaped caudal organ is musculo-glandular and is located ventrolaterally to the gut on the right side. It is characterized by the presence of a roughly Y-shaped internal channel that opens into two pores close to each other, which function for the intake and outlet of the (auto)sperm, respectively. The spermatozoa, which are peculiar and similar in the two species, are characterized by a long and complex acrosome consisting of four ultrastructurally distinct regions, three of which find equivalence in other gastrotrich species. The flagellum lacks a striated cylinder. Anatomy and ultrastructure enable us to hypothesize a modality of sperm transfer in Crasiella that is similar to that observed in Macrodasys.     

Protognathia n. gen. bathypelagica (Schultz, 1977) rediscovered in the Weddell Sea: A missing link between the Gnathiidae and the Cirolanidae (Crustacea,Isopoda)

Summary A new genus (Protognathia) and family (Protognathiidae) are described for Cirolana bathypelagica Schultz, 1977. The morphology of this unique species proves that the Gnathiidae are closely related to the Cirolanidae. The characters of P. bathypelagica are intermediate between the carnivorous cirolanids and the highly specialized gnathiid fish parasites.Abbreviations used in text and figures A 1,2 antenna 1,2 - Md mandible - Mx1 maxilla 1 - Mxp maxilliped - P 1-6 pereopods 1-6 - Plp 1-5 pleopods 1-5 - Tel telson - Urp uropod