44 research outputs found
A review of growth and life-history traits of native and non-native European populations of black bullhead Ameiurus melas
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TLR4 expression in ex-Lichenoid lesions—oral squamous cell carcinomas and its surrounding epithelium: the role of tumor inflammatory microenvironment
Abstract: Toll-like receptors (TLRs) regulate innate and adaptive immune responses. Moreover, TLRs can induce a pro-survival and pro-proliferation response in tumor cells. This study aims to investigate the expression of TLR4 in the epithelium surrounding oral squamous cell carcinomas (OSCC) in relation to its inflammatory microenvironment. This study included 150 human samples: 30 normal oral control (NOC), 38 non-lichenoid epithelium surrounding OSCC (NLE-OSCC), 28 lichenoid epithelium surrounding OSCC (LE-OSCC), 30 OSCC ex-non oral lichenoid lesion (OSCC Ex-NOLL), and 24 OSCC ex-oral lichenoid lesion (OSCC Ex-OLL). TLR4 expression was investigated by immuno histochemistry and the percentage of positive cells was quantified. In addition, a semiquantitative analysis of staining intensity was performed. Immunohistochemical analysis revealed that TLR4 is strongly upregulated in LE-OSCC as compared to normal control epithelium and NLE-OSCC. TLR4 expression was associated with the inflammatory environment, since the percentage of positive cells increases from NOC and NLE-OSCC to LE-OSCC, reaching the highest value in OSCC Ex–OLL. TLR4 was detected in the basal third of the epithelium in NLE-OSCC, while in LE-OSCC, TLR4 expression reached the intermediate layer. These results demonstrated that an inflammatory microenvironment can upregulate TLR4, which may boost tumor development
Risk assessment of non-native fishes in the catchment of the largest Central-European shallow lake (Lake Balaton, Hungary)
Population size structure indices and growth standards for Salmo (trutta) trutta Linnaeus, 1758 in Central Italy
The purpose of this study was to provide reference data on the growth and population structure of brown trout Salmo (trutta) trutta Linnaeus, in Central Italy. Standards for growth (percentiles and a standard growth model) were developed from the von Bertalanffy growth model by using length-at-age data obtained from 122 sampling sites in the River Tiber basin. Length-frequency indices provide a numeric estimation for deviations of the population structure from a balanced population. We adapted the traditional North American Relative Stock Density (RSD) and Proportional Stock Density (PSD) indices to brown trout populations in Central Italy by means of two methods. In the first method, the benchmarks of length categories were established by using percentages applied to the largest individual in the dataset. In the second method, asymptotic length and size at maturity were used to define the length categories for index calculation. Both methods were tested on length-frequency data from 263 sampling sites in the River Tiber basin. The results showed that the PSD calculated by the first method provided a better insight into the population structures of brown trout.
These results provide tools that will help ichthyologists and fish managers to compare the growth and population structure of brown trout throughout Central Italy
Population size structure indices and growth standards for
The purpose of this study was to provide reference data on the growth and population structure of brown trout Salmo (trutta) trutta Linnaeus, in Central Italy. Standards for growth (percentiles and a standard growth model) were developed from the von Bertalanffy growth model by using length-at-age data obtained from 122 sampling sites in the River Tiber basin. Length-frequency indices provide a numeric estimation for deviations of the population structure from a balanced population. We adapted the traditional North American Relative Stock Density (RSD) and Proportional Stock Density (PSD) indices to brown trout populations in Central Italy by means of two methods. In the first method, the benchmarks of length categories were established by using percentages applied to the largest individual in the dataset. In the second method, asymptotic length and size at maturity were used to define the length categories for index calculation. Both methods were tested on length-frequency data from 263 sampling sites in the River Tiber basin. The results showed that the PSD calculated by the first method provided a better insight into the population structures of brown trout.
These results provide tools that will help ichthyologists and fish managers to compare the growth and population structure of brown trout throughout Central Italy
BIOLOGY OF PROCAMBARUS CLARKII (GIRARD, 1852) IN LAKE TRASIMENO
The aim of this study was to gather more informations about the biological characteristics of Procambarus clarkii and to investigate the reasons of its rapid expansion in Lake Trasimeno. Specimens of both sexes (544 males and 624 females) were collected from October 2000 to November 2001. During the sampling period physical factors such as water temperature and hydrologic level of LakeTrasimeno were recorded. The study was conducted monthly in order to assess this species’ reproductive period. 1,168 specimens were analyzed for colour, sex, weight, and length. The sexual maturation of gonads was investigated in females. The results of this study evidenced that the population is in expansion, showing that Lake Trasimeno is an optimal habitat for this species
A COMPARATIVE STUDY ON THE FEEDING COMPETITION OF THE EUROPEAN PERCH PERCA FLUVIATILIS L. AND THE RUFFE GYMNOCEPHALUS CERNUUS (L.) IN LAKE PIEDILUCO (UMBRIA, ITALY).
The abundance of European perch in Lake Piediluco has significantly dwindled in the last few years. The present study on diet overlap between perch and ruffe was prompted by the rapid expansion of the ruffe stock in the lake. This species was first found in the lake in 1996 and has since become one of the most abundant. The degree of diet overlap between the two species was analyzed by using data on the stomach contents of 275 European perch and 328 ruffe. Results are expressed as abundance (%N), occurrence (%S), weight percentage (%W) and index of predominance (Ip). The diet overlap index (α) was calculated by means of Schoener’s formula using the %W of each food item. As an estimate of the diet width of both species, we used Levins’ indexes of niche breadth (B) and standardized measurement of niche breadth (BA). Both species are strictly carnivorous, feeding mainly on invertebrates: the most important diet components were dipterans and crustaceans, but the European perch also feeds on fish. In the perch, the Levins index was greater (B=4.332) than that calculated for the ruffe (B=2.262). During the ontogenesis of the European perch, there is a rather pronounced diet shift: dipterans form the largest portion of the diet at all ages, though in older perch fish-eating becomes increasingly evident. Benthic crustaceans tend to be consumed in greater quantities by the 3+ age-class, though they are also found in the stomachs of specimens of all ages. Ruffe, by contrast, do not display a pronounced ontogenetic diet shift.
The index of diet overlap between the two species was rather high, the maximum α value being 0.853; values indicate a high degree of diet overlap in the younger ageclasses (1+, 2+ and 3+), with a greater differentiation between the diets of the two species emerging as the age of the perch increased.
Our research also clarified some of the biological characteristics of the European perch in Lake Piediluco, namely, theoretical growth in length, weight at length and relative weight. These analyses enabled us to compare the growth characteristics of the European perch during periods when ruffe stocks differed in terms of abundance. All of the results indicate that the growth conditions of the European perch population in Lake Piediluco are steadily worsening. This provides indirect confirmation of a negative interaction with the ruffe
Reproductive properties of the chub Squalius squalus (Bonaparte, 1837) in the Assino Creek (Umbria, Italy)
This study investigated the reproductive properties of the population of chub
Squalius squalus (Linnaeus, 1758) in the Assino creek, one of the
largest tributaries of the upper course of the River Tiber. A total of 547 specimens were
caught monthly from March 2008 to May 2009. The age composition of the sample ranged
between 0+ and 11+. The sample was made up of 64.54% males and 35.46% females; sexual
maturity was attained in both sexes in the second year of life. Analysis of the
gonado-somatic index (GSI) and of the stage of gonad maturation throughout the year
suggests that the reproductive period of the population extends over a long time
(April–July). The relationship between total length and fecundity was
F = 5.466TL2.312. The mean number (±SE) of eggs produced
by each female was 15 351 ± 1705 and increased with the size and age of the specimens;
with regard to relative fecundity, an average value (±SE) of 53 553 ± 4098
eggs·kg-1 was observed. The mean diameter (±SE) of ripe eggs was
0.117 ± 0.004 cm. This study sheds light on some important characteristics of the
reproductive biology of the chub that have not been fully investigated in Italian
populations
Reproductive properties of the chub
This study investigated the reproductive properties of the population of chub
Squalius squalus (Linnaeus, 1758) in the Assino creek, one of the
largest tributaries of the upper course of the River Tiber. A total of 547 specimens were
caught monthly from March 2008 to May 2009. The age composition of the sample ranged
between 0+ and 11+. The sample was made up of 64.54% males and 35.46% females; sexual
maturity was attained in both sexes in the second year of life. Analysis of the
gonado-somatic index (GSI) and of the stage of gonad maturation throughout the year
suggests that the reproductive period of the population extends over a long time
(April–July). The relationship between total length and fecundity was
F = 5.466TL2.312. The mean number (±SE) of eggs produced
by each female was 15 351 ± 1705 and increased with the size and age of the specimens;
with regard to relative fecundity, an average value (±SE) of 53 553 ± 4098
eggs·kg-1 was observed. The mean diameter (±SE) of ripe eggs was
0.117 ± 0.004 cm. This study sheds light on some important characteristics of the
reproductive biology of the chub that have not been fully investigated in Italian
populations
Fishery biology of the goldfish Carassius auratus
The fishery biology of the goldfish Carassius auratus was studied in
Lake Trasimeno by analysing the selectivity of the equipment that can be used to control
this invasive species. Sampling was conducted monthly from February 2003 to January 2004
by means of electrofishing, fyke-nets and gill-nets of different-sized mesh (22, 25, 28,
35, 40, 50, 70 and 80 mm). The average value of the CPUEs of goldfish caught was 10175.48
g·10−2·m−2 for gill-nets, 246.97 g·h−1 for
fyke-nets and 606.50 g·min−1 for electrofishing. The efficiency of
electrofishing was not uniform in all periods of the year, the mean CPUEs being highest in
spring, when specimens of reproductive age were preferentially caught. Gill-nets yielded
abundant catches of goldfish in all seasons, and displayed good sampling efficiency even
in winter. With regard to the selectivity of gill-nets, estimated optimum selection
lengths for each mesh size were: 11.92 cm, 13.55 cm, 15.18 cm, 18.97 cm, 21.68 cm, 27.10
cm, 37.94 cm and 43.36 cm. The results of this research demonstrate that the various
fishing techniques can be effectively combined with the aim of controlling the goldfish
population in Lake Trasimeno