778 research outputs found
Development of sexual organs and fecundity in Octopus vulgaris Cuvier, 1797 from the Sardinian waters (Mediterranean Sea)
In this paper we report information about the sexual maturity process of 245 Octopus vulgaris specimens (75 females and 170 males) from the Mediterranean Sea. For both sexes, six stages of sexual maturity (immature, developing, maturing, mature, spawning, and spent) are identified on the basis of macroscopic and microscopic observations of the reproductive system and linked with some reproductive indices. A good correspondence between gonad appearance and its histological structure is observed, highlighting, in females, how oviducal gland morphology plays a crucial role in the macroscopic evaluation of maturity. The Gonadosomatic and Hayashi indices, in the two genders, and the Oviducal Gland index in females alone do not allow distinguishing all the stages in an irrefutable way. Data on the potential fecundity, oocyte and spermatophore size are reported and compared with literature. In addition, spermatophore components are also computed. The results reported in this paper lead to easy identification of the different phases of sexual maturation of O. vulgaris and could constitute an important tool for defining assessment models in view of sound management of this species
Development of sexual organs and fecundity in Octopus vulgaris Cuvier, 1797 from the Sardinian waters (Mediterranean Sea)
In this paper we report information about the sexual maturity process of 245 Octopus vulgaris specimens (75 females and 170 males) from the Mediterranean Sea. For both sexes, six stages of sexual maturity (immature, developing, maturing, mature, spawning, and spent) are identified on the basis of macroscopic and microscopic observations of the reproductive system and linked with some reproductive indices. A good correspondence between gonad appearance and its histological structure is observed, highlighting, in females, how oviducal gland morphology plays a crucial role in the macroscopic evaluation of maturity. The Gonadosomatic and Hayashi indices, in the two genders, and the Oviducal Gland index in females alone do not allow distinguishing all the stages in an irrefutable way. Data on the potential fecundity, oocyte and spermatophore size are reported and compared with literature. In addition, spermatophore components are also computed. The results reported in this paper lead to easy identification of the different phases of sexual maturation of O. vulgaris and could constitute an important tool for defining assessment models in view of sound management of this species
Reproductive patterns in deep versus shallow populations of the precious Mediterranean gorgonian Corallium rubrum ( Linnaeus, 1758) ( Sardinia, Central-Western Mediterranean)
This study quanti es the main reproductive features of the long-lived red coral Corallium rubrum, an octocoral endemic to the Mediterranean Sea and neighbouring Atlantic areas and one of the most valuable of all marine species, at different depths (38-40 m versus 96-115 m) in the north-western Sardinian waters (Central-Western Mediterranean Sea). Different population structures were observed with shallow colonies smaller (in basal diameter and height) than deeper ones. Both populations were all gonochoric at polyp and colony level and fertile. The sex-ratio was balanced in the deep red corals while in the shallow ones it was signi cantly biased towards female. Deep and shallow colonies were found to have a synchronous female sexual products development in the two depth ranges investigated. C. rubrum produced large female sexual products in both depth intervals in relationship with its reproductive mode, con rming a long oogenic development. In contrast to reproductive timing, the volume occupied by female sexual products per polyp was different between the populations, being higher in the deep than in the shallow populations. C. rubrum exhibited a reproductive strategy characterized by a relative low number of female sexual products per polyp revealing signi cant differences among the two depth ranges analyzed with a lower mean value of sexual products in the shallow colonies (mean fecundity per polyp: 1.14) than in the deeper ones (mean fecundity per polyp: 2.09). These results indicate differences in reproductive parameters such as sexual products distribution and reproductive output (fecundity) which were observed between shallow and deep populations of C. rubrum, in particular within deep dwelling populations
Small-scale distribution of metazoan meiofauna and sedimentary organic matter in subtidal sandy sediments (Mediterranean Sea)
While variations in sedimentary organic matter (OM) quantity, biochemical composition and nutritional quality as well as in meiofaunal abundance and assemblage composition at the macro- and mesoscale are relatively well known, information about variations at the microscale is much scarcer. To shed some light on this issue, we tested the null hypothesis by which abundance and composition of the meiofaunal assemblages, and the quantity, biochemical composition and nutritional quality of sedimentary organic matter in coastal shallow environments do not vary within a frame of 1 m2. No significant variation within the frame emerged for OM quantity, nutritional quality, biochemical composition and the abundance of meiofaunal assemblages. On the other hand, the composition of meiofaunal assemblages varied significantly within the frame and exhibited a clear segregation of assemblages farther to the shore, as a likely result of local micro-hydrodynamic conditions. Spatial autocorrelation analysis revealed that lipid and protein sedimentary contents had a random distribution, whereas carbohydrate and biopolymeric C contents and meiofaunal total abundance were characterized by a patchy distribution, with discrete peaks within the sub-frame squares (ca. 0.1 m2). Phytopigments showed a spatial positive autocorrelation distribution, following the micro-hydrodynamic pattern, with patches larger than the sub-frame square, but smaller than the entire one (1 m2). Overall, our results suggest that, within 1 m2 of subtidal sandy sediments, three replicates could be sufficient to assess correctly OM attributes and the abundance of meiofauna, but could be possibly inadequate for assessing meiofaunal assemblages’ composition at a finer scale (<1 m2)
Chemistry and clumpiness in planetary nebulae
We study the chemistry in the slow wind during the transition from AGB star
to pre-planetary nebula (PPN) and planetary nebula (PN). We show that there is
a very rich chemistry of degradation products created by photoprocessing,
driven by the gradually hardening radiation field of the central star. Most of
these products are, however, photodissociated during the PPN phase if the wind
is smooth. By contrast, if the wind is clumpy, possibly because of clumpiness
in the AGB atmosphere, then many of these degradation products survive into the
PN phase. Thus, chemistry may be used to infer the existence of clumpiness in
the AGB phase. We identify potential molecular tracers, and we note that, in
the case of clumpiness, large molecules may survive the transport from the
stellar atmosphere to the interstellar medium. We compare between our model
results with observations of three objects at differing evolutionary stages:
CRL618, NGC 7027 and the Helix nebula (NGC 7293).Comment: 7 pages, 4 figures, accepted for publication in MNRA
Application of numerical cladistic analyses to the Carnian-Norian conodonts: a new approach for phylogenetic interpretations
The high intraspecific variability of conodonts in the upper
Carnian-lower Norian interval and the proliferation of numerous
species in this relatively short stratigraphical time
generated many problems in the understanding of the Late
Triassic conodonts phylogeny, systematic and taxonomy.
The abundance of synonymies per species and the absence
of an established phylogenetic model contribute to
increase the issues concerning the conodonts systematic.
Unfortunately, being natural assemblages of the Late
Triassic conodont apparatuses still unknown, a multielement
approach to the problem would just introduce more
biases instead of solutions. The application of cladistic
methods to the platform elements, instead, may provide an
extremely valid methodology in the understanding of their
evolutionary relationships. Platforms are in fact the most
abundant conodont elements and they have well observable
evolutionary patterns and, thus, they can be considered as
the primary basis for the interpretation of the Late Triassic
conodont phylogeny.
We applied numerical cladistic analysis to the species belonging
to the five most widespread Late Triassic genera
(Paragondolella, Carnepigondolella, Metapolygnathus,
Epigondolella and Norigondolella) from the Pizzo Mondello
section (Sicani Mountains, Western Sicily, Italy),
GSSP candidate for the Norian (Mazza et al., 2010 and
references therein). This section provides several advantages
for these kind of taxonomic and cladistic studies
on conodonts: the section is a continuous succession of
pelagic carbonate sediments (Calcari con selce or Halobia
Limestone auctorum; Cherty Limestone, Muttoni et al.
2001, 2004; Guaiumi et al. 2007), characterized by uniform
facies, high sedimentation rates and, more important, it has
a rich conodont record which is representative of faunas
spread in the entire Tethys.
A taxon-character data matrix describing the distribution of
68 characters among 2 outgroup and 32 ingroup taxa was thus compiled and processed using PAUP* 4.1.
The analyses confirmed the validity of a series of evolutionary
trends among the platform elements, evidenced
the most important morphological characters for their
classification and led to a reinterpretation of the phylogenetic
position of the genera considered: Metapolygnathus
and Epigondolella resulted the only two monophyletic
groups and, thus, true phylogenetic genera; Paragondolella
a polyphyletic assemblage of basal members of
the ingroup; Norigondolella a paraphyletic series of taxa
bracketed by Paragondolella and Carnepigondolella a
paraphyletic group including all conodonts more derived
than Paragondolella and Norigondolella but outside the
Metapolygnathus and Epigondolella clades.
These results show the potentiality of applying cladistic
methods also to parataxonomic taxa. Parsimoniously
grouping by synapomorphies (shared derived characters)
provides a more informative classification than using
simple similarities (phenetics). A cladogram, in fact,
describing more of the character state changes than a phenogram,
gives a higher information content and provides
a more natural classification
Reproductive aspects of the velvet belly lantern shark Etmopterus spinax (Condrichthyes: Etmopteridae), from the central western Mediterranean sea. Notes on gametogenesis and oviducal gland microstructure.
In this paper, the reproductive biology of the velvet belly lanternshark Etmopterus spinax was analyzed in Sardinian waters (central western Mediterranean). This species was sexually dimorphic with females growing to a larger size than males. Marked sexual dimorphism in size was also observed along the vertical gradient. Histological analysis of gonads was very useful in assigning macroscopical maturity stages. The investigation on the microstructure of oviducal gland (OG) highlighted four morphofunctional zones with mucous and/or proteic secretions according to the zone and to their specific functions and development. Sperm in the OG was found for the first time in E. spinax. The localization of sperm storage tubules deeper in OG suggested long-term sperm storage, which is in agreement with the long reproductive cycle described. This species matured late, specifically at 80.7% and 79% at the maximum observed size for females and males respectively. Mature specimens were found throughout the year with pregnant females observed in winter and autumn. A low fecundity was observed with a mean ovarian fecundity of 16.5 mature follicles
A shared pottery-making tradition? Early Roman Ware 1 from Cartagena and Elche (Spain)
The so-called Early Roman Ware 1, identified by P. Reynolds in the Alicante region, was widely distributed in the eastern part of the Iberian Peninsula. The presence of this ware in Elche (Alicante) and Valencia opened the possibility that it was widely distributed across the region. Indeed, it has been considered as a possible regional product of the area of Valencia. In Cartagena (ancient Carthago Nova), where our study concentrated originally, ERW1 is relatively common in 2nd and 3rd century CE contexts and has been considered as a local product. The question here is whether the ERW1 detected in Cartagena is the same as known in the Elche and Valencia re- gions? Were they the product of the same workshop or production center and subsequently distributed across the region? Or do we have several production centers, sharing a technological tradition but operating in different areas? To explore this problem, we have initially characterized 29 samples from this Early Roman Ware 1 found in Cartagena (Murcia) and Elche (Alicante), using a combination of analytical techniques. WD-XRF was used for the chemical characterization, XRD for the mineralogical characterization, and, finally, optical microscopy of thin- sections was applied to investigate the petrographic features. The results of the petrographic characterization indicate the existence of a major petrographic fabric group sharing compositional features. Chemistry reveals a slightly more complex picture. One sample originates in an area of metamorphic geology, possibly in Cartagena, while the other samples, although their provenance is still unknown, most probably originated elsewhere, exploiting kaolinitic clay
A taxonomic survey of female oviducal glands in chondrichthyes: A comparative overview of microanatomy in the two reproductive modes
Oviducal glands (OGs) are distinct expanded regions of the anterior portion of the oviduct, commonly found in chondrichthyans, which play a key role in the production of the egg in-vestments and in the female sperm storage (FSS). The FSS phenomenon has implications for understanding the reproductive ecology and management of exploited populations, but little information is available on its taxonomic extent. For the first time, mature OGs from three lecithotrophic oviparous and four yolk-sac viviparous species, all considered at risk from the fishing impacts in the central western Mediterranean Sea, were examined using light microscopy. The OG microanatomy, whose morphology is generally conserved in all species, shows differences within the two reproductive modalities. Oviparous species show a more developed baffle zone in respect to viviparous ones because of the production of different egg envelopes produced. Among oviparous species, Raja polystigma and Chimaera monstrosa show presence of sperm, but not sperm storage as observed, instead, in Galeus melastomus and in all the viviparous sharks, which preserve sperm inside of specialized structures in the terminal zone
La ciudad romana de Pollentia: el foro
This is the revision of the different periods of Pollentia's forum since the beginning of the first quarter of the 1st. century BC until the Islamic period. We point out the documented reforms in the early Empire and also in the 3rd. century AD with special attention to the fortified precinct built in the late period over what had been the forum of the city.Revisión de las diversos períodos de ocupación del foro de Pollentia, desde sus inicios en el primer cuarto del siglo I a.C. hasta la época islámica, destacando las reformas documentadas para época alto imperial y las del siglo III d.C, con especial atención al recinto fortificado que se construyó en época tardía en el antiguo foro de la ciudad
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