Effects of temperature on two Mediterranean population of Dinophilus gyrociliatus (Polychaeta: Dinophilidae): II. Effects on demographic parameters

The effects of temperature on demographic characteristics of two populations from Ravenna and Genoa of the polychaete Dinophilus gyrociliatus were investigated. Temperature affects age-specific survival and fecundity and all the demographic parameters often to a different degree in the two populations. Individuals from Ravenna survive longer than those from Genoa. The most evident differences in the age-specific fecundity curves of the experimental groups are related to age at maturity and the duration of the reproductive period that are in inverse proportion to temperature. In both populations of D. gyrociliatus, the maximum daily fecundity is observed at intermediate temperatures. In all cases, the Genoa females mature earlier, attain their maximum fecundity more quickly and have a shorter reproductive period than their Ravenna counterparts.Age at maturity, fecundity during the first reproductive events and juvenile survival are by far the most important characteristics in determining the fitness of the two populations at the tested temperatures. Even though the greatest net growth rates and highest expectation of life were recorded at 12 °C in the Ravenna population, the delay in the attainment of sexual maturity means that, at this temperature, the population growth rate is lowest. The higher juvenile survivorship and the greater fecundity observed at 24 °C is counter-balanced by the early attainment of sexual maturity induced at 30 °C. The comparison of the population growth rate calculated in laboratory with field data suggests that temperature is one of the main environmental parameters determining the fitness of D. gyrociliatus.     

The shell of <Emphasis Type="Italic">Hexaplex (Trunculariopsis) trunculus</Emphasis> (Gastropoda: Muricidae) as a mobile hard substratum for epibiotic polychaetes (Annelida: Polychaeta) in the Ria Formosa (Algarve coast—southern Portugal)

This work reports and illustrates secondary colonisation of Hexaplex (Trunculariopsis) trunculus shells by polychaetes in the Ria Formosa lagoon (Algarve coast—southern Portugal). Information is presented in terms of qualitative and quantitative data on epibiotic polychaetes, fouling frequency, degree of epibiosis, preferential areas for colonisation and incidence of shell damages. A total of 2,880 polychaetes belonging to 10 families were identified. Besides Spirorbidae (not quantified), the most abundant families were Serpulidae (67.5%), Sabellidae (10.2%), Sabellariidae (9.6%) and Cirratulidae (8.5%). From a total of 2,264 T. trunculus individuals analysed for epibiosis, 28.4% were non-fouled, 66.8% were intermediately fouled and 4.8% were heavily fouled. The fouling frequency, degree of epibiosis and incidence of damages in the shell spire increased markedly with T. trunculus shell length. Some epibiotic polychaetes were located preferentially on/or nearby particular features of T. trunculus shells, which probably facilitate settlement and tube construction, in addition to provide some protection against tube damage. The main consequences of epibiosis (benefits and disadvantages) for the gastropod basibiont (T. trunculus) are discussed. The present study apparently indicates that besides burrowing into soft bottom substrates, sporadic inter-tidal exposure and mutual predation on epibiosis, T. trunculus lacks other typical antifouling defence adaptations. Handling editor: K. Martens     

On the associations between Haplosyllis (Polychaeta, Syllidae) and gorgonians (Cnidaria, Octocorallaria), with the description of a new species

The present paper includes a morphological, ecological and biological updating of the three gorgonian associated species of Haplosyllis (Polychaeta, Syllidae) known to date: H. chamaeleon (symbiont with Paramuricea clavata in the Mediterranean), H. anthogorgicola (symbiont with Anthogorgia bocki in the Japanese seas) and H. villogorgicola , a new species living symbiotically with Villogorgia bebrycoides which is only known from Tenerife (Canary Islands, Eastern Central Atlantic). The new species is described on the basis of ecological, morphological, morphometric and statistical analysis of relevant characteristics. Each host colony harboured about 15 pale-yellowish worms, whose cryptic colouration mimicked that of the host. They occurred either on the host branches or partly hidden inside cavities formed by the fusion of two branches. The new species is characterized by the presence of simple chaetae with clearly bidentate tips all along the body, the presence of gland pore aggregates distributed in two lateral rows and two ventral patches on each palp and the absence of ciliary tufts on the pharyngeal papillae. H. villogorgicola sp. nov. is closely related to H. chamaeleon . Thus, it is compared with two populations of this species collected in the north-west and south-west Mediterranean. Stolons of H. chamaeleon are re-described as tetracerous and a peculiar posterior end regeneration process occurring in adult worms during the stolon formation is described. H. anthogorgicola is also re-described, with particular emphasis on its appendage and chaetal arrangements. The main features of the three associations are discussed in light of the current knowledge on symbiotic polychaetes, particularly cnidarian-associated syllids.  © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 77 , 455–477.     

Ultrastructure of opisthosomal chaetae in Vestimentifera (Pogonophora, Obturata) and implications for phylogeny

Schulze, A. 2000. Ultrastructure of opisthosomal chaetae in Vestimentifera (Pogonophora, Obturata) and implications for phylogeny. — Acta Zoologica (Stockholm) 82 : 127–135
The posterior segmented body region of Vestimentifera bears rows of uncini that function to anchor the animal within its tube. SEM studies of five vestimentiferan species reveal intraspecific and interspecific variation in the number of chaetigerous segments and the arrangement of uncini within a given segment. The portion of an uncinus that extends beyond the epidermis comprises two opposing groups of teeth that probably correspond to the capitium and subrostral process of polychaete uncini, and a distinct protuberance between them, interpreted as a rostrum. In Ridgeia piscesae , the uncini are formed by chaetal follicles, consisting of a chaetoblast, a follicle cell and an epidermis cell. The chaetal shaft is elongate and composed of up to 40 hollow cylinders that are invaded at their base by microvilli from the apical part of the chaetoblast. Opisthosomal chaetae in perviate Pogonophora are usually restricted to four per segment and are of a rod-shaped type. It is hypothesized that the rod-shaped chaetae represent reduced hooked chaetae probably derived from a condition such as found in Monilifera. Uncini of Pogonophora, Sabellida, Terebellida and Oweniida are considered homologous but details of chaetal design may be due to functional adaptations and thus do not represent reliable characters for phylogenetic studies on higher taxonomic levels than genera or potentially families.     

Isolation and characterization of five serine proteases with trypsin-, chymotrypsin- and elastase-like characteristics from the gut of the lugworm Arenicola marina (L.) (Polychaeta)

Summary Five proteases were isolated from the digestive fluid of the lugworm, Arenicola marina L. The enzymes (molecular weight 24.0–24.6 kDa) were classified as serine proteases. Three enzymes showed a cleavage specificity corresponding to mammalian trypsin (E.C. 3.4.21.4). One protease possessed a chymotrypsin-like cleavage pattern (E.C. 3.4.21.1), and the fifth preferred cleavage behind short-chain amino acids like an elastase (E.C. 3.4.21.36). Detailed investigations revealed differences in molecular characteristics and cleavage patterns compared to mammalian proteases, especially in the chymotrypsin- and the elastase-like enzymes.Abbreviations APNE N-acetyl-d/l-Phe -naphthyl ester - BANA N-benzoyl-d/l-Arg -naphthylamide - BAPNA N-benzoyl-d/l-Arg-4-nitroanilide - BIGGANA N-benzoyl-l-Ile-l-Glu-Gly-l-Arg-4-nitroanilide - BLPNA N-benzoyl-d/l-Lys-4-nitroanilide - BTEE N-benzoyl-l-Tyr ethyl ester - enzyme T1/T2/T3 trypsin-like enzyme - enzyme ChT chymotrypsin-like enzyme - enzyme E elastase-like enzyme - GPANA N-glutaryl-l-Phe-4-nitroanilide - MUF 4-methylumbelliferryl - MW molecular weight - PMSF phenylmethylsulphonyl fluoride - SAAPPNA N-succinyl-l-Ala-l-Ala-l-Pro-l-Phe-4-nitroanilide - SBTI soybean trypsin inhibitor - SPPNA N-succinyl-l-Phe-4-nitroanilide - TAME N-tosyl-l-Arg methyl ester - TFA trifluoracetic acid - TLCK N-tosyl-l-Lys chloromethyl ketone - TPCK N-tosyl-l-Phe chloromethyl ketone - TRIS tris(hydroxymethyl)aminomethane     

Occurrence and coexistence in Nereis diversicolor O.F. Müller (Annelida Polychaeta) of substances immunologically related to vertebrate neuropeptides

Summary Numerous immunochemical and immunohistochemical studies have shown a wide distribution of several families of neuropeptides in invertebrates as well as vertebrates. There are relatively few data available for Annelida: Polychaeta. Therefore, we undertook an immunohistochemical investigation in the marine worm Nereis.Among the vertebrate type antibodies tested, those against met-enkephalin, LH-RH, vasopressin, oxytocin and ACTH had negative or only very slight effects. Slight to moderate reactions were obtained for VIP, SRIF, CRF, GRF, and leu-enkephalin. Moderate to very strong responses were found with anti-CCK/gastrin, -substance P, and --MSH sera. Immunopositive reactions were usually observed in the entire CNS (except, until now, in neurosecretory cells, type II, in nuclei 20, and in nerve fibres located in the infracerebral neurohemal area). The immunoreactivity was, however, more or less abundant according to different CNS regions. For example, it appeared that the immunostaining for CRF is more important in the VNC while the leu-enkephalin family is more abundant in the brain (particularly in fuchsinophilic neurosecretory cells, type I, in nuclei 20). Moreover, several vertebrate type peptides (such as CRF/GRF and CCK/gastrin) may coexist in a single neurone. Several antisera may elicit a positive reaction in some specific area (for example, substance P in the nuchal organ; SRIF in oocytes; CCK/gastrin in the gastrointestinal tract).Nothing is known about the role of the different substances immunologically detected in Nereis. It is suggested that CCK/gastrin-, -MSHand substance P-like materials transmit external stimuli to neurosecretory centres located in the caudal part of the brain.Principal Abbreviations used ACTH adrenocorticotropic hormone - CCK cholecystokinin - CRF corticotropin-releasing factor - GRF growth hormone-releasing factor - LH-RH luteinizing hormone-releasing factor - MSH melanocyte-stimulating hormone - sP substance P - SRIF somatotropin release-inhibitory factor - VIP vasoactive intestinal peptide - AE anterior eye - AG anterior group - CA corpora allata - CC corpora cardiaca - CNS central nervous system - CP corpora pedunculata - EP epidermis - ICR infracerebral region - MG medial group - n nerve - NO nuchal organ - NP neuropile - OC optic commissure - Oo oocyte - PE posterior eye - PF paraldehyde fuchsin - PF⁺ fuchsinophilic - PF^- not fuchsinophilic - Pn palpal nerve - S septum - VNC ventral nerve cord The roman and arabic numerals respectively refer to different nerves and nuclei     

Fine structure of the spermatozoon of <Emphasis Type="Italic">Diopatra neapolitana</Emphasis> (Polychaeta,Onuphidae)

The identification of Diopatra species lacks of clear diagnostic features of taxonomic importance and the knowledge of their reproductive characters is scant. The spermatozoa of Diopatra neapolitana were ultrastructurally investigated by electron microscopy in order to correlate the mode of reproduction with sperm cells morphology. The mature male gamete has a depressed subspherical nucleus, a cone-like acrosome, and a long flagellum. The acrosome is conical in shape and radially symmetrical, with a base diameter twice the height. Within the acrosome vesicle, the basal region includes a very electron-dense thickened ring composed of paracrystalline substances. The subacrosomal space is filled with a poorly electron-dense material, with straight filaments axially arranged to form a perforatorium. The nucleus contains the complete axial canal, holding the hind perforatorium region. The middle piece consists of five mitochondria with well-distinct membranes and tubulo-vesicular cristae. Two centrioles are located perpendicularly to each other. The proximal one lies in the central fossa and the distal one, slightly eccentric to the sperm axis, anchors to the plasma membrane by nine satellite rays of the pericentriolar complex. The axoneme has a 9+2 arrangement of microtubules. In general, the spermatozoon of D. neapolitana conforms exteriorly to the typical ect-aquasperm; the acrosome complex ultrastructure, however, shows noticeable modifications from the basic form. This finding agrees with the previously observed reproductive pattern (broadcast spawning—free-swimming larvae) of D. neapolitana belonging to Santa Gilla population, and may be helpful to solve the taxonomic problems of the D. neapolitana complex as well.     

Morphological variation in Polydora ciliata complex (Polychaeta: Annelida)

Intraspecific variation in Polydora ciliata (Johnston) was assessed on the basis of evidence from morphological characters, which were studied by scanning electron microscopy. Differences were observed between populations of P. ciliata with respect to the setae of the fifth modified segment and in the caruncle. Two other species, namely P. ligni Webster and P. limicola (Annenkova), were also studied in order to assess interspecific variation. The two forms of P. ciliata , that is boring and non-boring, were found to be different morphologically.