391 research outputs found
First records of Gastrotricha from South Africa, with description of a new species of Halichaetonotus (Chaetonotida, Chaetonotidae)
During a survey of the biota of the St. Lucia Estuary in the iSimangaliso Wetland Park, South Africa, a number of Gastrotricha were found among samples of meiofauna. Fresh, marine sediment yielded several specimens belonging to a total of seven species. Of these, two are already known from other regions (i.e., Dactylopodola australiensis and Heteroxenotrichula squamosa), one is described as new to science (Halichaetonotussanctaeluciae sp. n.), while the remaining four (Pseudostomella sp., Halichaetonotus sp.1, Halichaetonotus sp. 2, Xenotrichula sp.) require further collections and analysis, in order to establish the extent of their affiliation to species already described. General appearance, shape of hydrofoil scale and the occurrenceof three long spines on the dorsal side make the new species most closely related to H. australis and H. marivagus. The key differences from these taxa and between Halichaetonotus sanctaeluciae sp. n. and H. aculifer are discussed
A new species of Turbanellidae (Gastrotricha, Macrodasyida) from Jamaica, with a key to species of Paraturbanella
The study falls within the framework of a wider research programme aimed at investigating the gastrotrich
diversity of the Tropical North-Western Atlantic (TNWA). A new macrodasyidan gastrotrich is described
from fine-medium sand collected at Duncans Bay, Jamaica. The description is based on observations carried
out on living specimens using differential interference contrast microscopy. Paraturbanella xaymacana
sp. n., the third gastrotrich taxon reported from Jamaica, is a mid-sized species, up to 564 \u3bcm long, with
a feeble peribuccal swelling. The most obvious autapomorphic traits pertain to the testes and the male
pore, both of which are located approximately at mid body, rather than at- or near the pharyngo-intestinal
junction as occur in the other species of the genus. Additional differences with congeners are discussed and
a key to the Paraturbanella species is provided, in the hope it will be useful to both gastrotrich experts and
marine ecologists who discover these microscopic metazoans during their research
An Integrated Morphological and Molecular Approach to the Description and Systematisation of a Novel Genus and Species of Macrodasyida (Gastrotricha)
Background
Gastrotricha systematics is in a state of flux mainly due to the conflicts between cladistic
studies base on molecular markers and the classical systematisation based on morphological
traits. In sandy samples from Thailand, we found numerous macrodasyidan gastrotrichs
belonging to an undescribed species of difficult taxonomic affiliation. The abundance and
original nature of the specimens prompted us to undertake a deep survey of both morphological
and molecular traits aiming at a reliable systematisation of the new taxon.
Methodology/Principal Findings
Using several microscopical techniques we investigated the external and internal anatomy,
including the muscular and nervous systems of the new species. Additional specimens
were used to obtain the 18S rRNA gene sequence; molecular data was analysed cladistically
in conjunction with data from additional species belonging to the near complete Macrodasyida
taxonomic spectrum. Specimens are vermiform, up to 806 \u3bcm in total length, and
show a well-defined head equipped with peculiar leaf-like sensorial organs and a singlelobed
posterior end. The adhesive apparatus includes anterior, ventrolateral, dorsal and
posterior tubes. Pharynx is about 1/4 of the total length and shows pores at its posterior 3/4.
Adult specimens exhibit maturing eggs and a bulky, muscular caudal organ, but do not
show sperm nor the frontal organ. Musculature and nervous system organisation resemble
the usual macrodasyidan plan; however, the somatic circular muscles of the intestinal
region surround all other muscular components and a third FMRFamide-IR commissure
ventral to the pintestinal junction appear to be an autoapomorphic traits of the new
species. Conclusions/Significance
While the anatomical characteristics of the Asian specimens appear so unique to grant the
establishment of a new taxon, for which the name Thaidasys tongiorgii gen. et sp. nov. is
proposed, the result of phylogenetic analyses based on the 18S rRNA gene unites the new
genus with the family Macrodasyidae
Density Estimates and Habitat Preferences of Two Sympatric Bird Species as Potential Bioindicators of Tropical Forest Alterations
Forestry management can shape the structure of habitat types and have important biological consequences on the composition of biodiversity. This study focused on Momotus lessonii and Eumomota superciliosa, two potential bioindicators of local and wide scale tropical forest alterations. The study took place in the Karen Mogensen Wildlife Refuge (Costa Rica), a protected area characterized by two main forest habitats where the two species coexist, i.e., primary moist and second-growth dry forest. A distance sampling method was used to obtain density estimates for each species. A spot mapping approach showed an apparent partitioning of the two species at the site. The Kilometric Abundance Index (KAI) and statistical analyses revealed significant differences between the two habitats, i.e., E. superciliosa tended to be more abundant and preferred the dry forest, whilst M. lessonii favored moist environments. The development of arid and semi-arid environments characterized by open areas will probably lead to a numerical increase in E. superciliosa with a consequent expansion, while the decline of moister and homogeneously forested environments will likely affect negatively M. lessonii. We argue that these birds will act as bioindicators of local and global environmental changes, and their monitoring will enable appropriate forest management decisions for conservation purposes
GENETIC AND PRODUCTIVE CHARACTERIZATION OF THE BURLINA CATTLE BREED
The Burlina (BUR) is a local Italian cattle breed, its main feature is to be a small sized animal well adapted to live in difficult environment such as mountain areas. Nowadays only 350 cows are enrolled in the Italian Herd Book due to its substitution by more productive breeds. This study proposes a phenotypic and genetic characterization of the BUR breed in comparison with Holstein Friesian (HFR) and Brown Swiss (BSW). The comparison of productive traits showed lower production than HFR and BSW as well as longer productive life and more favourable reproductive traits in BUR animals. The genetic analyses, performed by microsatellites markers, showed the high level of heterozygosity and the genetic distinctiveness of BUR. These findings approve the feasibility of a conservation scheme and suggest the profitability of breeding BUR, especially in difficult environment where the low production can be compensated by longevity and the economic loss by the added value of its typical dairy production
GENETIC CHARACTERISATION OF ITALIAN CHICKEN BREEDS USING A PANEL OF TWENTY MICROSATELLITE MARKERS
Genetic relationships among four Veneto native breeds of chickens were studied on the basis of microsatellites polymorphisms. A total of 190 DNA samples (45 Robusta Lionata, 43 Robusta Maculata, 45 Ermellinata di Rovigo, 45 Pèpoi) and a commercial broiler line (12 Golden Comet) were genotyped at 20 microsatellite loci. The average number of alleles per locus was 5 and the expected heterozygosity resulted lower for the local breeds than for the commercial broiler line used as reference. The inbreeding coefficient showed a deficit of heterozygotes, highest for the Robusta Lionata breed. Nei’s standard genetic distances corrected for bias due to sampling of individuals (Da), based on allele frequencies, and Reynolds distances (DReynolds) were calculated among breeds. The Robusta Lionata and Robusta Maculata resulted very similar approving the same genetic origin. A Neighbor-Joining tree drawn from DReynolds distances clustered three groups, one including the Robusta Lionata and Robusta Maculata breeds, the second one formed by the Ermellinata di Rovigo and the Golden Comet commercial line and the third by the Pèpoi. The results showed the genetic differences occurring between the local chicken breeds
Effect of crossbreeding on milk yield traits and somatic cell score in dairy cattle
This study aimed to estimate trends of heterosis for milk yield traits and somatic cell score (SCS) in the Dutch dairy cattle. First lactation data on 305-d milk, fat, and protein yield, and on average 305-d SCS recorded on pure Holstein Friesian (HF), Dutch Friesian (DF), Mosa Reno Yssel (MRY), and F1 crossbreds (DFxHF and MRYxHF) were considered. According to cows' year of calving, productive records from animals calving from 1980 to 2004 were divided in five periods, while SCS records from animals calving from 1990 to 2004 were divided in four periods. Data were processed using analysis of variance (ANOVA) according to a linear model which included effects of herd, season of calving, age at calving, and the genotype by period of calving interaction effect. Moreover, a linear covariate of sire's estimated breeding value (EBV) for 305-d milk yield was added to the model for yield traits. Heterosis values for productive traits were positive but decreased over time. For 305-d milk yield these values changed from 7.5 to 3.0% in the DFxHF crossbreds, and from 9.0 to 1.0% in the MRYxHF crossbreds. Average heterosis for SCS (-1.2%) was small and negative with a favourable trend over years
GENETIC ASPECTS OF MILK COAGULATION PROPERTIES IN DAIRY CATTLE
Authors reviewed the genetic aspects of milk coagulation ability focusing on heritability and genetic correlation values and on the breed and milk protein loci effects on rennet coagulation time and curd firmness. The review discussed milk and cheese yield production all over the world concluding that the per capita retail demand for cheese will increase with a mean annual growth rate of 0.8%. Therefore, in the future, cheese production will continue to be one of the major livestock food products around the world. The development of new payment systems for milk considering the intrinsic value for cheese making ability, could be an important opportunity for select best individual within dairy cattle breeds and to preserve, among dairy cattle breeds, those with high milk coagulation properties. Often these genetic resources, beyond their genetic value, also exercise a positive influence on sustainability of milk production in fragile environments, such as mountain areas, preserving an important cultural value (history, traditions, arts, and literature)
- …