Case building behaviour of the caddis fly larva, Lepidostoma hirtum

On hatching from the egg, a larva of Lepidosroma hirtum Curtis constructed a tubular, sand grain case. As the larva became older it periodically added new material to the anterior of the case and, once in every instar except the 1st, cut off ⅓ to ¼ of the posterior of the case. In the 3rd instar the larva changed from adding sand grains to cutting out and attaching almost rectangular leaf panels. By the 5th instar the case was composed entirely of leaf panels. The case was then square in section and composed of one row of panels for each of the sides. The panels were not truly rectangular but convex on the leading edge and sides and concave at the back, so that the anterior convexity of one panel fitted into the posterior concavity of the panel in front. Panels were arranged with their long axes across the case. The seams between panels in the roof were half a panel length out of phase with those in the sides but in phase with those in the floor. The convex sides of a panel allowed it to overlap the seams between panels on the two adjacent sides. If a 5th instar larva was removed from its case it first built a sand grain case followed by a leaf panel case. The animal cut panels from the leaf with its mandibles and then further shaped them by chewing round the edge. Just prior to pupation, the case was modified by the attachment of further panels to the anterior; these included panels which for the first time in the life of the larva were arranged with their long axes along the case.     

Regionalisation of the endoderm progenitors and morphogenesis of the gut portals of the mouse embryo

This fate-mapping study reveals that the progenitors of all major parts of the embryonic gut are already present in endoderm of the early-head-fold to early-somite stage (1-9 somites) mouse embryo. The anterior endoderm contributes primarily to the anterior intestinal portal of the early-organogenesis stage (16-19 somites) embryo. Endoderm cells around and lateral to the node are allocated to the open “midgut” region of the embryonic gut. The posterior (post-nodal) endoderm contributes not only to the posterior intestinal portal but also the open “midgut”. Descendants of the posterior endoderm span a length of the gut from the level of the 3rd-5th somites to the posterior end of the embryonic gut. The formation of the anterior and posterior intestinal portals is accompanied by similar repertoires of morphogenetic tissue movement. We also discovered that cells on contralateral sides of the anterior endoderm are distributed asymmetrically to the dorsal and ventral sides of the anterior intestinal portal, heralding the acquisition of laterality by the embryonic foregut.     

Halalaimus algeriensis n. sp. (Nematoda) from the Sahara

During a trans-Saharan expedition in 1980 a number of samples were collected from stagnant and running fresh and slightly saline water bodies. One of them, collected from the Oued En-Namous in a small oasis yielded several interesting nematodes, among which was a newHalalaimus species described herein asHalalaimus algeriensis n. sp. It comes close toH. minusculus Tchesunov, 1978, but differs in tailshape, absence of males and habitat. It also resembles the marine speciesH. gracilis de Man, 1888, but differs in the relative length of the anterior setae, the absence of a lateral field and absence of males. The new species can be differentiated fromH. stammeri Schneider, 1940, the only fresh water species found hitherto, by its shorter body, more anterior and wider fovea, and the length and position of the anterior setae. The various juvenile stages can be separated on the basis of body length, foveal length and genital primordium.     

The transmission and effect on yield of ryegrass mosaic virus in a filtered air environment

The eriophyid mite vectors of ryegrass mosaic virus (RMV) were excluded from ryegrass by covering plots with a polyethylene film house ventilated by filtered air. Initially plots were manually inoculated to give different levels of RMV. During two seasons no mites were found within the house so that all transmission of virus was by sap. Rolling and frequent cutting of uninfected plots decreased yields, but surprisingly, increasing virus infection did not decrease yields significantly. Cutting transmitted virus within infected plots but not from infected to healthy plots, whereas combined rolling and cutting did transfer virus to healthy plots.     

Physiological regulation of long-term oviposition in the house cricket, Acheta domesticus

In house crickets [Acheta domesticus (L.)] a single mating early in adult life sufficed to induce egg laying for the duration of the life of a female. Female house crickets mated readily shortly after adult emergence but oviposition did not commence until about 12–14 days after emergence, even though females matured eggs by 7 days. The egg-laying factor associated with mating remained active during prolonged periods of substrate deprivation during which the female did not oviposit. If the spermatophore was removed prematurely shortly after a mating, the long-term, egg-laying response was truncated and was correlated with a dramatic decline in the fertility of eggs which were oviposited. The egg-laying stimulus appeared to act in the spermatheca, apparently through neural means, since denervation of the spermatheca abolished mating-induced oviposition. These results indicate that the oviposition factor found in the testes is able to act for long periods of time and has to be present continually in order to be effective. Furthermore, the long-term oviposition stimulus in the house cricket may be different from prostaglandin E2 which induces a prompt ovipositional response.     

Behavioural evidence for detection of the repellent polygodial by aphid antennal tip sensilla

Abstract. Close-up video was used to record responses of the aphid Myzus persicae (Sulzer) (Homoptera: Aphididae) to the plant-derived repellent polygodial. When 0.1% (±)-polygodial was painted onto one half of a Chinese cabbage leaf disc, and the other half treated with the ethanol solvent, apterous adult aphids avoided walking onto the polygodial-treated area during 15 min access periods. Similarly, when the rim of a small plastic Petri dish was treated with polygodial, aphids took significantly longer to walk off the base of the dish and onto the rim, compared with insects in solvent-treated control dishes. Analysis of video-recordings indicated that aphids were repelled following contact of antennal tips with the polygodial-treated areas of leaf or plastic. In contrast, aphids with both antennal tips surgically removed showed no apparent response to polygodial treatment of leaf or plastic surfaces. Aphids were placed between polygodial- and solvent-treated angled glass cover slips to enable unilateral presentation of polygodial on either the left or right side of the insects. Most aphids with antennae intact moved away from the polygodial-treated side, but removal of both antennal tips again negated the response. When the tip was removed from only one antenna, and the other remained intact, unilateral presentation caused a repellent response only if polygodial occurred on the same side as the intact antenna. Presentation of polygodial on both sides of aphids (bilaterally) caused no response if both antennal tips were intact or removed, but aphids with only one antennal tip removed were repelled from the side where the antenna remained intact. The results indicate that aphids detect polygodial upon contact with sensilla located on the antennal tips, and that the repellent response occurs as a negative chemotropotaxis following unilateral stimulation of these sensilla. Contact between the antennal tips and glass substrates was demonstrated using a fluorescent pigment.     

Immune expulsion of the nematode Aspiculuris tetraptera from mice given primary and challenge infections.

The distribution of larval Aspiculuris tetraptera was studied in 4-week-old male and female CFLP mice. Whereas on days 10–12 the larvae were entirely confined to the anterior third of the colon, by day 14 larvae could be found throughout the colon. After day 17 the larvae were again restricted to the anterior colon. This change in distribution was co-incident with a loss of a large proportion of the worm burden, which occurred more consistently in female than in male mice.The degree of acquired immunity stimulated by various immunizing regimens was assessed by the survival of a challenge infection in experimental and control mice. It was found that a high level of immunity was achieved by exposure to a 19-day primary infection, a 36-day low-level infection and also by three 6-day infections, in each of which the larvae were removed by piperazine treatment immediately after the crypt phase.     

Estrous cycle regulation in the whitefooted mouse (Peromyscus leucopus) with special reference to vaginal cast formation

The estrous cycle of the whitefooted mouse (Peromyscus leucopus) was consistent with those described for most small rodents and closely resembled that of the house mouse and the rat in timing. The presence of the male did not accelerate puberty nor induce cycle synchrony, but was critical in establishing cycle regularity. Females isolated from influences of males never attained a pattern of concistent cycle length. Development of the vaginal epithelium during estrus was excessive in both isolated and non-isolated females, resulting in a "cast" of cornified epithelium which could be removed intact during metestrus. Casts removed during the making of vaginal smears measured up to 20 mm in length and still left a sufficient residue of cells which could be detected in all stages of the estrous cycle.     

FLAGELLAR ELONGATION AND SHORTENING IN CHLAMYDOMONAS : The Use of Cycloheximide and Colchicine to Study the Synthesis and Assembly of Flagellar Proteins

Flagella can be removed from the biflagellate Chlamydomonas and the cells begin to regenerate flagella almost immediately by deceleratory kinetics. Under usual conditions of deflagellation, more than 98% of all flagella are removed. Under less drastic conditions, cells can be selected in which one flagellum is removed and the other left intact. When only one of the two flagella is amputated, the intact flagellum shortens by linear kinetics while the amputated one regenerates. The two flagella attain an equal intermediate length and then approach their initial length at the same rate. A concentration of cycloheximide which inhibits protein synthesis permits less than one-third of each flagellum to form when both flagella are amputated. When only one is amputated in cycloheximide, shortening proceeds normally and the degree of elongation in the amputated flagellum is greater than if both were amputated in the presence of cycloheximide. The shortening process is therefore independent of protein synthesis, and the protein from the shortening flagellum probably enters the pool of precursors available for flagellar formation. Partial regeneration of flagella occurs in concentrations of cycloheximide inhibitory to protein synthesis suggesting that some flagellar precursors are present. Cycloheximide and flagellar pulse-labeling studies indicate that precursor is used during the first part of elongation, is resynthesized at mid-elongation, and approaches its original level as the flagella reach their initial length. Colchicine completely blocks regeneration without affecting protein synthesis, and extended exposure of deflagellated cells to colchicine increases the amount of flagellar growth upon transfer to cycloheximide. When colchicine is applied to cells with only one flagellum removed, shortening continues normally but regeneration is blocked. Therefore, colchicine can be used to separate the processes of shortening and elongation. Radioautographic studies of the growth zone of Chlamydomonas flagella corroborate previous findings that assembly is occurring at the distal end (tip growth) of the organelle.     

The backward jump of a box moss mite

Indotritia cf. heterotrichia, a box moss mite 800 μm in length, combines the abilities to curl up and to jump. Despite the lack of specialized legs and of extensor muscles in its knee joints, the backward leap is characterized by a short take-off time (ca. 0.5 ms). This is apparently facilitated by a catch mechanism made up of a small hook on each forefemur that hitches on the rim of the anterior shield of the body and maintains the forelegs in a flexed position during a prejump phase. While the animal is propelled backwards, its body simultaneously spins in a forward direction: it is supposed that, at take-off, the hindlegs initiate a forward rolling of the body, which is powered by internal hydraulic pressure, before the hook disengages from the shield rim and triggers a sudden backward impulse. The non-parabolic trajectory of the flight can be described with a model where the air resistance due to the spin (Magnus effect) and to the translatory motion is taken into account.     

The Role of Endogenous Abscisic Acid in the Correlation Between the Cotyledon and Its Axillary Bud in PeaPisum sativum L

On cutting off one cotyledon from decapitated pea seedlings cultivated in the dark, the apical dominance is restored, as is well-known, by the growth of the bud of the removed cotyledon. As early as 12 h following cotyledon amputation(i.e. at the time when buds of both cotyledons-remaining and removed-are not yet differentiated in size), a decrease in the level of endogenous abscisic acid can be demonstrated in the bud of the removed cotyledon.     

Littorellicola billhawkinsi n. gen., n. sp. (Digenea: Aporocotylidae) from the myocardial lacunae of Florida pompano, Trachinotus carolinus (Carangidae) in the Gulf of Mexico; with a comment on the interrelationships and functional morphology of intertrabecular aporocotylids

Littorellicola billhawkinsi n. gen., n. sp. infects the myocardial lacunae of the ventricle and atrium of Florida pompano, Trachinotus carolinus in the northern Gulf of Mexico. It differs from other aporocotylid genera by the combination of having a body 10–30× longer than wide, a posterolateral body protuberance, lateral spine rows, an aspinous anterior sucker comprising a slightly muscular rim circumscribing the mouth, asymmetrical posterior ceca 14–20× length of the anterior ceca and lacking diverticula or secondary rami, tens of testes distributing in a cobblestone-like field anterior and posterior to the distal ends of the posterior ceca, an oviducal seminal receptacle comprising the distal portion of the oviduct, and a post-cecal ovary plus by lacking rosethorn-shaped spines, a pharynx, and a Laurer's canal. The new species appears host specific to Florida pompano because no conspecific infection was detected in 134 carangids of 8 species in 4 genera captured nearby the type locality. Psettarium sebastodorum Holmes, 1971 is transferred to the new genus, as Littorellicola sebastodorum (Holmes, 1971) n. comb., because it and the new species differ from species of Psettarium by the combination of having multiple testes plus 8 other features detailed herein. This report brings the number of nominal Gulf of Mexico aporocotylids to 12 species of 8 genera, represents only the second record of an aporocotylid from a carangid there, and supports the notion that elongated, “thread-like” aporocotylids with lateral spine rows are seemingly well-adapted for infecting myocardial lacunae or embedding in the myocardium of their definitive fish hosts.     

Altering the length of the lipopolysaccharide O antigen has an impact on the interaction of Salmonella enterica serovar Typhimurium with macrophages and complement

A panel of isogenic Salmonella enterica serovar Typhimurium strains that vary only in the length of the O antigen was constructed through complementation of a wzz double mutant (displaying unregulated O-antigen length) with one of two homologous (wzzST and wzzfepE) or three heterologous (wzzO139 of Vibrio cholerae and wzzSF and wzzpHS-2 of Shigella flexneri) wzz genes. Each gene was functional in the S. enterica serovar Typhimurium host and specified production of O-antigen polymers with lengths typical of those synthesized by the donor bacteria (ranging from 2 to >100 O-antigen repeat units). By use of this panel of strains, it was found that O-antigen length influences invasion/uptake by macrophage cells; this is the first time this has been shown with Salmonella. O-antigen length was confirmed to be related to complement resistance, with a minimum protective length of >4 and <15 repeat units. O antigen of 16 to 35 repeat units was found to activate complement more efficiently than other lengths, but this was unrelated to complement resistance. No evidence was found to suggest that modifying the length of the O-antigen polymer affected expression of the O1, O4, or O5 antigenic factors.     

Three-dimensional reconstruction of the musculature of Cossura pygodactylata Jones, 1956 (Annelida: Cossuridae)

The musculature of adult specimens of Cossura pygodactylata was studied by means of F-actin labelling and confocal laser scanning microscopy (CLSM). Their body wall is comprised of five longitudinal muscle bands: two dorsal, two ventral and one ventromedial. Complete circular fibres are found only in the abdominal region, and they are developed only on the border of the segments. Thoracic and posterior body regions contain only transverse fibres ending near the ventral longitudinal bands. Almost-complete rings of transverse muscles, with gaps on the dorsal and ventral sides, surround the terminal part of the pygidium. Four longitudinal bands go to the middle of the prostomium and 5–14 paired dorso-ventral muscle fibres arise in its distal part. Each buccal tentacle contains one thick and two thin longitudinal muscle filaments; thick muscle fibres from all tentacles merge, forming left and right tentacle protractors rooted in the dorsal longitudinal bands of the body wall. The circumbuccal complex includes well-developed upper and lower lips. These lips contain an outer layer of transverse fibres, and the lower lip also contains inner oblique muscles going to the dorsal longitudinal bands. The branchial filament contains two longitudinal muscle fibres that do not connect with the body musculature. The parapodial complex includes strong intersegmental and segmental oblique muscles in the thoracic region only; chaetal retractors, protractors and muscles of the body wall are present in all body regions. Muscle fibres are developed in the dorsal and ventral mesenteries. One semi-circular fibre is developed on the border of each segment and is most likely embedded in the dissepiment. The intestine has thin circular fibres along its full length. The dorsal blood vessel has strong muscle fibres that cover its anterior part, which is called the heart. It consists of short longitudinal elements forming regular rings and inner partitions. The musculature of C. pygodactylata includes some elements that are homologous with similar muscular components in other polychaetes (i.e., the body wall and most parapodial muscles) and several unique features, mostly at the anterior end.     

Paramphistomum cervi: Surface topography of the tegument of adult fluke

Adult Paramphistomum cervi or rumen fluke are pear-shaped, slightly concave ventrally and convex dorsally. The worm measures about 5-13 mm in length and 2-5 mm in width across the mid-section. As observed by scanning electron microscopy (SEM), the tegumental surface in all part of the body, appears highly corrugated with transverse folds alternating with grooves and is spineless. At high magnification, the surface of the fold is composed of microfolds or ridges separated by microgrooves or pits. Corrugations and invaginations of the ventral surface are also more extensive than on the dorsal surface of the body. Both anterior and posterior suckers have thick rims covered with transverse folds without spine. The genital pore is situated at the anterior third of the body. There are two types of sensory papillae on the surface: type 1 is bulbous in shape, measuring 10-15 μm in diameter at the base with nipple-like tips, and type 2 has a similar shape and size and also a short cilia on top. These sensory papillae usually occur in large clusters, each having between 5 and 20 units depending on the region of the body. Clusters of papillae on the ventral surface and around the anterior suckers tend to be more numerous and larger in size. The dorsal surface of the body has the least number of papillae.     

Division of labor: Subsets of dorsal-appendage-forming cells control the shape of the entire tube

The function of an organ relies on its form, which in turn depends on the individual shapes of the cells that create it and the interactions between them. Despite remarkable progress in the field of developmental biology, how cells collaborate to make a tissue remains an unsolved mystery. To investigate the mechanisms that determine organ structure, we are studying the cells that form the dorsal appendages (DAs) of the Drosophila melanogaster eggshell. These cells consist of two differentially patterned subtypes: roof cells, which form the outward-facing roof of the lumen, and floor cells, which dive underneath the roof cells to seal off the floor of the tube. In this paper, we present three lines of evidence that reveal a further stratification of the DA-forming epithelium. Laser ablation of only a few cells in the anterior of the region causes a disproportionately severe shortening of the appendage. Genetic alteration through the twin peaks allele of tramtrack69 (ttk^twk), a female-sterile mutation that leads to severely shortened DAs, causes no such shortening when removed from a majority of the DA-forming cells, but rather, produces short appendages only when removed from cells in the very anterior of the tube-forming tissue. Additionally we show that heterotrimeric G-protein function is required for DA morphogenesis. Like TTK69, Gβ13F is not required in all DA-forming follicle cells but only in the floor and leading roof cells. The different phenotypes that result from removal of Gβ13F from each region demonstrate a striking division of function between different DA-forming cells. Gβ mutant floor cells are unable to control the width of the appendage while Gβ mutant leading roof cells fail to direct the elongation of the appendage and the convergent-extension of the roof-cell population.     

Identification of the laminar-inducing factor: Wnt-signal from the anterior rim induces correct laminar formation of the neural retina in vitro

To study the molecular mechanism that controls the laminar organization of the retina, we utilized reaggregation cultures of dissociated retinal cells prepared from chicken embryos. These cells cannot generate laminated structures by themselves and, instead, form rosettes within the reaggregates. However, the dissociated cells can organize into a correctly laminated structure when cultured in the presence of a putative laminar inducing factor coming from particular tissue or cells, but its molecular identity of this factor has long remained elusive. In this study, we found that the anterior rim of the retina sends a signal to rearrange the rosette-forming cells into a neuroepithelial structure characteristic of the undifferentiated retinal layer. This activity of the anterior rim was mimicked by Wnt-2b expressed in this tissue, and was neutralized by a soluble form of Frizzled, which works as a Wnt antagonist. Furthermore, the neuroepithelial structure induced by Wnt-2b subsequently developed into correctly laminated retinal layers. These observations suggest that the anterior rim functions as a layer-organizing center in the retina, by producing Wnt-2b.     

Description of the glochidium of Margaritifera auricularia (Spengler 1793) (Bivalvia,Unionoidea)

The glochidium of Margaritifera auricularia is described for the first time by using light microscopy, scanning electron microscopy and histological techniques. The larval mantle is formed by only two layers of cells; the inner one being much thicker, with microvilli. All cell masses of the glochidium are temporary aggregations that are the rudiments of organs of the subsequent juveniles which will be released after metamorphosis in the host tissues. In the glochidium there are three main masses of cells: (i) the muscle, which is in an anterior position; (ii) the oral plate in the centre of the larva; and (iii) the more ventrally and posteriorly situated ventral plate, or foot rudiment, flanged with lateral pits all bearing dense cilia. No rudimentary organs such as the pericardium, the kidney, the heart or nerve ganglia have developed. There are no visible hooks in the valve margins, but by using light microscopy we observed minute teeth covered by a rim of the periostracum. Near the margin of the shell there are two pairs of sensory hair tufts only observable by scanning electron microscopy. The glochidium of M. auricularia is the largest of the family Margaritiferidae and intermediate between the glochidium of the known species of this family and those of Unionidae.     

New data on the range,biology, and abundance of skilfish Erilepis zonifer (Anoplopomatidae)

Data on the occurrence, spatial-bathymetric distribution, and size composition of skilfish Erilepis zonifer are given on the basis of the materials collected at the long-line catches on the Emperor Ridge seamounts. This fish is a large representative of fam. Anoplopomatidae (maximal length 188 cm; weight 88.5 kg). From June to July 2009, the species was found on all five sampled underwater mountains (Nintoku, Jingu, Ojin, Koko, Northern Koko). The fish was found within the depth range 370–1040 m. The initial biomass of skilfish at the studied seamounts calculated by the Leslie method is approximately 203.5 tons. The structure of the range and possible ways of the dispersion of this species in the waters of the continental slope of the North-Pacific rim are discussed.