Some observations in tetraclita squamosa rufotincta Pilsbry

Aspects of the biology of Tetraclita squamosa rufotincta Pilsbry were investigated. Although a tropical species, on the shores at Elat, Israel, its breeding is virtually restricted to the colder winter months. The causal factors are considered and the results of some experimental work relative to temperature control given.For a cirripede, T.s. rufotincta has a remarkably large ‘egg’ — unusual in a tropical or even warm-water species. The egg size is compared with that of other species and the survival value of large size considered; excess nutrients are carried over from the embryo to at least the first planktonic larva, and may aid survival in a relatively nutrient poor environment.The animals do not become sexually mature until the second year after their settlement. Growth takes place largély in the colder winter months and is seasonally separated from the period when gonadal tissue is developed.     

Studies in the biochemistry of cirripede eggs. VI. Changes in the general biochemical composition during development of Tetraclita squamosa rufotincta Pilsbry,Balanus perforatus Brug., and Pollicipes cornucopia Darwin

The carbohydrate, protein, lipid, total RNA and DNA at four stages in the development of the eggs of Tetraclita squamosa rufotincta Pilsbry, Balanus perforatus Brug., and Pollicipes cornucopia Darwin have been determined. The initial caloric content varies with species, that of the large egg of Tetraclita being extremely high; on a relative volume-specific basis, however, differences, although still present, are much less variable. A comparison has been made with other species. Those eggs in which lipid predominates over protein in Stage I lose more lipid during development. The relatively large quantities of reserves in Tetraclita may serve as metabolic substrate during the development of the planktonic larvae under nutrient-poor conditions.     

Feeding of nauplius stages of Eudiaptomus gracilis on mixed plastic beads

Eudiaptomus gracilis makes up 30–40 and 80–90% ofthe zooplankton in Lake Balaton during the summer and the winterrespectively. More than half of the species population consistsof nauplii We studied feeding and size selectivity of naupliiin suspensions which contained polystyrol latex beads in a concentrationdose to the natural seston. Guts of NI nauplii were free ofboth beads and remnants of natural food Of NII–NVI nauplii,67–87% took in beads. Older animals consumed more andlarger particles. The maximum diameter of ingested beads reached29 µm On an average, NII nauplii took in 128 µm³of beads in 10 min, whereas older animals consumed 615–900µm³. The clearance rate remained below 0 01 µl h^–1NII nauplii strongly preferred 1 2 µm particles Oldernauplii did not show any preference or selected only slightlyfor the smallest particles. Nauplii rejected 4–11 µmbeads. In some cases a weak positive selection could be observedtoward 12 µm or larger beads.     

The ecology of the free-living stages of Trichostrongylus vitrinus

Callinan A. P. L. 1979. The ecology of the free-living stages of Trichostrongylus vitrinus. International Journal for Parasitology9: 133–136. The ecology of the free-living stages of Trichostrongylus vitrinus was studied in western Victoria in 1975–1976. Where development of eggs (E₁–E₂) did occur, preinfective larvae (L₁–L₂) were recovered within 0–8 days, infective larvae (L₃) in faeces within 10–39 days and on L₃ herbage and soil within 4–26 days. The mean development time to L₃ on herbage and soil was 12.5 ± 4.8 days and the mean development time to maximum yield of these was 37.9 ± 9.7 days. The mean percentage of L₃ on herbage and soil actually on herbage was 70.8 ± 6.5 %. L₃ persisted in faeces for up to 106 days and on herbage and soil for up to 208 days. Yields of L₃ on herbage and soil varied from 0 to 5.05 % of the number of eggs deposited. Yields were highest from those eggs deposited in autumn-winter. No L₃ were observed to survive over summer.     

Wound-stimulated moulting and calcification responses in the adult cirripede Balanus balanoides (L.)

Earlier studies of hormonal action in adult barnacles have involved the injection of crustecdysone into the basal mantle space through a hole drilled in the shell. The drilling and injection result in increased moulting activity and in calcification within the mantle tissue around the site of injection. A preliminary investigation of the nature and causes of these responses has been carried out. The increase in moulting activity is distinct from that induced by injected crustecdysone and can be sustained over several months, the level of stimulation depending upon whether the adults are subjected to single or multiple injections. The associated calcification extends from the shell wall and develops as a layer around an area of wound tissue at the injection site. It appears that these moulting and calcification activities are healing responses to wounding and that the processes involved may be similar to those of other arthropods. Moulting in barnacles is apparently controlled by an ecdysone hormonal system and these results suggest that such a system may be implicated in the control of calcification.     

The morphology and histology of the cirripede pemis

The general morphology and detailed histology of the penis of two common boreo-arctic cirripedes, Balanus balanoides (L.) and B. balanus (L.) have been investigated. The penis is a highly extensible, annulated organ beset with four rows of sensory setae. The paired vesiculae seminales unite within the pedicel of the penis to give the single ductus. Distally, the exoskeleton is invaginated into this ductus. Circular muscles are present in the vesiculae seminales but do not continue into the penis. The histology of the ductus epithelium indicates a secretory nature as does that of a specialized group of cells, termed the ‘cushion’, towards the distal end: this group of cells is surrounded by circular muscle bands. Longitudinal muscles extend virtually the whole length of the penis; they give off fibres which are inserted at the junctions of the annulations. The muscles of the pedicel are described. Paired nerves in the pedicel give rise to four in the penis. The sensory innervation of the setae is described. The possible functional relations of the structure to the activities of the penis at copulation and during the emission of semen is discussed.     

Relative tolerance of cirripede larval stages to acute thermal shock: A laboratory study

(1) Meroplankters drawn into once-through cooling circuits of coastal power plants are subjected to transient thermal stress. The effect of such acute thermal shock on the development of barnacle larvae was studied in the laboratory.

(2) The response of the barnacle larvae (naupliar and cyprid stages) to elevated temperature was dependent on exposure time and their stage of development.

(3) Among the stages tested, N-6 larvae showed maximum tolerance. Exposure to 37°C did not affect larval survival, but delayed development of N-2 larva to cypris by one day.

(4) Exposure at 40°C delayed, hastened or did not affect the development time of N-2 and N-4 larvae through cypris, depending on exposure time.

(5) Ten mins exposure at 43°C proved lethal to all larval stages with mortality ranging from 20 to 86%.

(6) Development success of the surviving larvae, measured in terms of cypris yield, showed no significant difference from controls, at temperatures below 40°C.

(7) Settlement activity was significantly affected in only those cyprid larvae which were exposed to 43°C for 10 min.

(8) Results of the present study indicate that thermal stress experienced in the once-through cooling system does not have significant impact on survival and development of the barnacle larvae at temperatures of 37–40°C.     

Effect of turbulence on the feeding and moulting of the cirripede Balanus Balanoides (L.) given an algal diet

The shell growth, moulting, and faecal pellet production of Balanus balanoides (L.) have been investigated experimentally in turbulent and quiet conditions. In turbulent conditions an algal food level of 50% was sufficient to maintain the same shell growth as at the 100% level, whereas at this level in quiet conditions growth was less than at 50% with turbulence. At the 10% food level growth was markedly reduced in quiet conditions. On the assumption that production of faeces is a measure of feeding activity, the latter is stimulated by turbulence as is the moulting rate. The relation between production of faeces and moulting is, however, independent of water movement. Faecal pellet production continues at higher algal food levels after the growth rate has become constant indicating that when assimilation is maximal there is no feed-back mechanism regulating food intake.     

The biochemical composition of the cement of a pedunculate cirripede

The composition of the cement of Lepas fascicularis Ellis & Solander in terms of carbohydrate, lipid, and amino-acid composition of the protein has been determined: in this species the cement acts as a float. The major constituent is protein. The lipid content lies between that given for Balanus spp. while the protein contains a larger proportion of glutamic acid and smaller proportions of lysine and histidine.     

Studies in the biochemistry of cirripede eggs. VII. Changes in the general biochemical composition during development of Chthamalus dentatus Krauss and Octomeris angulosa Sowerby

The carbohydrate, protein, total lipid, RNA, and DNA have been determined at four stages during the embryonic development in two chthamalids, Chthamalus dentatus Krauss and Octomeris angulosa Sowerby, from the South African coast. These values were compared with those of some cirripedes from the northern hemisphere. There is a relatively high utilization of lipids during the development as was previously found in Chthamalus montagui Southward. The relative volume specific energy content is similar to other cirripedes, but clearly higher than that of boreo-arctic balanids. The energy loss in C. dentatus is 54.4% of the initial energy content and that of Octomeris angulosa is 39.4%. This is lower than that found in Chthamalus montagui, but higher than that of all other cirripedes studied and especially the boreo-arctic species. The possibility of geographical significance of these differences is discussed.     

Drosophila larval foraging behaviour: Developmental stages

Two distinct developmentally related behaviour patterns can be identified in third-instar larvae of Drosophila melanogaster, ‘foraging’ behaviour and ‘wandering’, a pre-pupation behaviour. An age-related change in behaviour from foraging to wandering is quantified by measuring larval locomotion at the early, middle and late third instar in an environment where food is distributed in patches. Strain, moisture, food and inhomogeneities in the texture of the surface of the medium significantly influence larval locomotory behaviour.     

Studies in the biochemistry of cirripede eggs. IV. The free Amino-acid pool in the eggs of Balanus balanoides (L.) and B. balanus (L.) during development

Changes in the ‘free’ amino acids, betaine, and trimethylamine oxide during the development of the eggs of Balanus balanoides (L.) and B. balanus (L.) have been determined; the results are given in terms of μM/g dry wt, μM/g water, and μM/10⁶ eggs. The amino acids are derived from the yolk proteins the net composition of which is known. Free amino acids are present in considerable quantity, as is commonly the case with crustacean tissue. Changes in the individual amino acids are discussed. B. balanus eggs contain large, and relatively constant, amounts of sarcosine; its function is unknown but large quantities are present in the more highly evolved cirripedes so far examined. A possible relation between betaine glycine, and sarcosine relative to choline metabolism is considered. Large amounts of taurine are present. There is a striking increase in β-alanine in the late stages of development; in B. balanoides it comes to be the most, and in B. balanus the third most common amino acid; its possible involvement in purine metabolism is considered. The relation between the amounts of the various entities in the eggs and in the bodies of the adult are examined.     

Phylogenetic implications of the Crustacean nauplius

The plesiomorphic mode of crustacean development is widely accepted to be via a larva called the nauplius. Extant taxa like the Cephalocarida, Branchiopoda, Ostracoda, Mystacocarida, Copepoda, Cirripedia, Ascothoracida, Facetotecta, Euphausiacea and Penaeidea hatch from an egg as a free-living nauplius. Other crustaceans show an embryonic phase of development suggestive of a naupliar organization. Several features of the nauplius larva have been proposed as diagnostic characters for the Crustacea: a median (nauplius) eye; at least three pairs of head appendages (antennules, antennae, mandibles); a posteriorly directed fold (the labrum) extending over the mouth and a cephalic (nauplius) shield. The relationship between trilobite protaspis with at least four appendages and the crustacean nauplius remains unclear, but reports of a copepod orthonauplius with four appendages are rejected. Swimming is suggested to represent the underived mode of locomotion for the crustacean nauplius, and that naupliar swimming directly results in naupliar feeding which also is underived.     

The organic and inorganic composition of some cirripede shells

The protein, chitin, calcium, and magnesium present in the shells of several species of cirripedes have been determined; the powdered shell material was also examined by differential thermal analysis (DTA). Chthamalus sp., in which lamina of epicuticular matter are present within the shell, show the greatest organic content. When the organic material is separated into its protein and chitin components the latter is present in similar quantities in all species; this reflects a similar quantity of the chitin-protein matrix. Reduction in the protein content of heavily eroded C. depressus seems to be due to the removal of protein by endolithic algae. The $\text{Ca}\text{Mg}$ ratio increases from extreme hypobiotic to exposed C. depressus. There is a marked correlation between the $\text{Ca}\text{Mg}$ ratio and the organic content and it is suggested that the magnesium is largely associated with protein rather than with the calcitic lattice. This receives support from the thermal analyses. Small quantities of quartz were detected by X-ray analysis.     

Ultrastructure of early stages of Rozella allomycis (Cryptomycota) infection of its host, Allomyces macrogynus (Blastocladiomycota)

This study reconstructs early stages of Rozella allomycis endoparasitic infection of its host, Allomyces macrogynus. Young thalli of A. macrogynus were inoculated with suspensions of R. allomycis zoospores and allowed to develop for 120 h. Infected thalli at intervals were fixed for electron microscopy and observed. Zoospores were attracted to host thalli, encysted on their surfaces, and penetrated their walls with an infection tube. The parasite cyst discharged its protoplast through an infection tube, which invaginated the host plasma membrane. The host plasma membrane then surrounded the parasite protoplast and formed a compartment confining it inside host cytoplasm. The earliest host-parasite interface within host cytoplasm consisted of two membranes, the outer layer the host plasma membrane and the inner layer the parasite plasma membrane. At first a wide space separated the two membranes and no material was observed within this space. Later, as the endoparasite thallus expanded within the compartment, the two membranes became closely appressed. As the endoparasite thallus continued to enlarge, the interface developed into three membrane layers. Thus, host plasma membrane surrounded the parasite protoplast initially without the parasite having to pierce the host plasma membrane for entry. Significantly, host-derived membrane was at the interface throughout development.     

Ultrastructure of some developmental stages of Helicosporidium sp. in the navel orangeworm, Paramyelois transitella

The ultrastructure of the developmental stages of Helicosporidium sp. is described from the early spherical cell stage to the maturation and germination of the spore. The presence of well-defined Golgi bodies and mitotic division of the nucleus suggests that this pathogen is not an ascomycete, as had been previously reported, and indicates an affinity to the Protozoa.     

Evolution of the nauplius stage in malacostracan crustaceans*

This article gives an overview on some aspects of malacostracan development at the levels of gene expression, cell division, and shape of embryos and larvae. The various modes of development found in malacostracans are discussed in a phylogenetic and an evolutionary framework. It is suggested that the plesiomorphic condition within the Malacostraca is an embryonized egg‐nauplius which is characterised by a yolky egg, precocious development of the three anteriormost head segments, an antero‐ventrally folded caudal papilla, and a growth zone formed by rings of 19 ecto‐ and eight mesoteloblasts. Several alterations of this malacostracan ground pattern occurred concerning the arrangement and the number of teloblasts, the shape of the embryo and the timing of segmentation with respect to the naupliar segments. From their distribution within the phylogenetic tree and from their larval characteristics it is concluded that the free‐living nauplius larvae of euphausiids and dendrobranchiate decapods are secondarily evolved from ontogenies without a free‐living nauplius. Because the nauplius stage is lost in several malacostracan taxa, the concept of the nauplius as a phylotypic stage of crustaceans is refuted. In addition, the nauplius as an example of the recapitulation of ancestral characters is discussed.     

Studies in the biochemistry of cirripede eggs. V. Changes in the general biochemical composition during development of Chthamalus stellatus (Poli)

The biochemical composition of the eggs of Chthamulus stellatus (Poli) during their development has been investigated. The eggs are incubated within the mantle cavity of the adult but no substrates are contributed by the latter. Carbohydrates, protein, and lipid are all utilized. In contrast to two cold-water species, Balanus balanoides and B. balanus perviously investigated lipid rather than protein is consumed during the early stages. Possible explanations for this are considered.     

Hemicelluloses of Arundo donax at different stages of maturity

The hemicellulosic composition of the internodes of Arundo donax depends on the maturity of the tissue. The percentage of xylose in the total hemicellulose increases with increasing plant maturity. The main hemicellulose is an arabino-4-O-methyl glucurono xylan which is already present in the youngest tissues and has the same structural features regardless of the age of the tissues. The average D.P. of this polysaccharide increases from about 60 to 150 with maturation of the plant tissue.