1,721,029 research outputs found
Advances in the anatomic study of the interscapular region of the cat
Full text linkNew clinical oriented approaches are supported by the integration of advanced imaging techniques, e.g. computed tomography and magnetic resonance, with gross anatomy imaging. The interscapular region of the cat is a typical site of a highly invasive infiltrative pathology, i.e. Feline Injection-Site Sarcoma. Even if chemotherapy and radiotherapy have been considered as pre-surgical therapies, extensive surgery is still the recommended treatment. Evidence suggested that the relationships between muscles, infiltrative mass and adjacent musculoskeletal structures could change according to the forelimb positions: a fact to be duly considered while planning the surgical approach. Anatomic and tomographic atlases provide only images of the interscapular region from cats positioned with their forelimbs extended cranially, which means that, they do not record musculoskeletal modifications due to the forelimb movements. Aim of this study was to provide detailed images of the changes occurring in the musculoskeletal structures of the interscapular region of cats according to their forelimb position by comparing cross-sectional gross anatomy, computed tomography and magnetic resonance imaging
Role of gap junction-mediated communications in regulating large-scale chromatin configuration remodeling and embryonic developmental competence acquisition in fully grown bovine oocyte
Full text linkPURPOSE:
This study was aimed to test the hypothesis that gap junction mediated communications (GJC) are required to allow the progressive chromatin configuration remodeling (from GV1 to GV3) process to occur in fully grown oocytes in order to gain the final step of developmental competence acquisition, and that a premature disruption of GJC can alter this process.
METHODS:
Bovine cumulus-oocytes complexes collected from medium antral follicles were cultured for 2, 4, 6 and 8 h in the presence of 10-4 IU/ml of r-hFSH and with 2 mM of the non-selective PDE inhibitor 3-isobutyl-1-methyl-xanthine (IBMX) to prevent meiotic resumption. GJC functionality and chromatin configuration were monitored during the culture period. After meiotic arrest, the developmental capability of oocytes was assessed after IVM and IVF.
RESULTS:
IBMX was effective in significantly sustaining GJC up to 6 h and maintaining meiotic arrest, when compared to control group. Moreover, the percentage of oocytes with less condensed chromatin (GV1) decreased within 4 h of culture, while the proportion of GV2 oocytes gradually increased up to 6 h. Interestingly, a decline in the proportion of GV2 oocytes and an increase in the proportion of GV3 oocytes were observed after 6 h of culture, when the major drop of GJC occurred. On the contrary, when GJC were uncoupled by adding 3 mM of 1-heptanol or through cumulus cells removal, chromatin condensation occurred rapidly throughout the culture period, more promptly in denuded oocytes. Moreover, the maintenance of GJC during meiotic arrest was accompanied by a significant increase of developmental competence compared to the control, as indicated by a higher percentage of hatched blastocysts and blastocyst cell number.
CONCLUSIONS:
Altogether, our data indicate that both paracrine and junctional mechanisms are involved in modulating large-scale chromatin structure during the final phase of oocyte differentiation
Dynamics and regulatory mechanisms involved in immature oocyte chromatin remodeling
No full textDuring meiotic arrest, and particularly during the oocyte growth phase leading to the formation of fully-grown oocyte, the chromatin enclosed within the oocyte nucleus, also known as Germinal Vesicle (GV), is subjected to several levels of regulation controlling both its structure and function. These events include mechanisms acting both locally, on specific loci, and on a large scale to remodel wide portions of the oocyte genome. Morphologically, the chromosomes lose their individuality as well as their characteristic appearance and form a loose chromatin mass, which in turn undergoes profound and dynamic rearrangements within the GV before the meiotic resumption. These ‘large-scale chromatin configuration changes’ are temporally correlated with the process of transcriptional silencing in the oocyte nucleus as well as with epigenetic modifications such as histone tail modifications and changes in the global level of DNA methylation. Moreover, chromatin configuration rearrangements are tightly associated with the acquisition of meiotic and developmental competence. The molecular mechanisms governing changes in large-scale chromatin configuration still remain largely unknown. Most likely, strategies set in place for the control and coordination of these events are part of a complex physiological process that ultimately confers the oocyte with meiotic and developmental competence. Here, we summarize some studies intended to explain the mechanism(s) regulating this complex process
On the chromatin of the immature oocyte : from morphology to function and regulatory mechanisms mediated by follicular cells
Full text linkIn her comment entitled ‘Nuclear histochemistry: its history in fifty volumes’ (Eur J Histochem 2006; 50:79-81) Maria Gabriella Manfredi Romanini referred to “nuclear histochemistry” as a “real molecular biology in situ, applied to research on dynamic processes in the nucleus, which makes the microscopic and histo- chemical approach absolutely irreplaceable for the progress of our understanding of cell biology”. These words perfectly exemplify the research path that is elucidating the process of remodeling of chromatin configuration within the nucleus of the mammalian oocyte. This process, which occurs towards the end of the oocyte differentiation phase before meiotic resumption, has received much attention in the last decade since it has a tremendous impact on the capability of the oocyte to generate an embryo after fertilization. The study of the oocyte chromatin by means of classical morphological and histochemical approaches has given a fundamental contribution to our understanding of oocyte biology and has paved the way to functional and mechanistic studies. Several research groups worldwide, including ours, are indeed dedicating a large amount of studies to find the relationship between morphological and functional aspects of the oocyte chromatin remodeling process, to reveal the molecular mechanisms involved, as well as to clarify the contribution of the follicular compartment. Here, we summarize some studies intended to give insight into the mechanism(s) regulating this complex process, including recent findings indicating that ovarian granulosa cells and their coupling with the oocyte through gap junctions are implicated in such a process
Developmental competence of gametes reconstructed by germinal vesicle transplantation from fresh and cryopreserved bovine oocytes
No full textOBJECTIVE:
To evaluate the use of fresh or frozen bovine oocytes as an animal model for reconstructing artificial gametes by germinal vesicle transplantation (GVT), to study nucleocytoplasmic interaction and define clinical procedures for ooplasm donation in humans.
DESIGN:
Prospective experimental study.
SETTING:
University-based experimental laboratory.
ANIMAL(S):
Bovine oocytes from slaughterhouse ovaries.
INTERVENTION(S):
A total of 446 gametes were reconstructed from fresh immature oocytes; nuclear and cytoplasmic competencies were analyzed through the assessment of meiotic progression and cytoskeleton reorganization; embryonic developmental capability was evaluated after parthenogenetic activation of metaphase II (MII) reconstructed oocytes. Furthermore, the distribution of mitochondria in karyoplast and cytoplast in grafted oocytes was studied. Finally, meiotic and developmental competencies were determined in 199 gametes reconstructed from vitrified immature oocytes.
MAIN OUTCOME MEASURE(S):
Maturational and developmental rate of reconstructed oocytes, cytoskeleton organization, and mitochondrial distribution.
RESULT(S):
Gametes reconstructed from either fresh or cryopreserved immature oocytes showed similar meiotic competence (41.6% vs. 37.7%, respectively). All reconstituted oocytes that reached MII displayed a normal distribution of cytoskeletal elements. Embryonic developmental capability was higher in oocytes derived from fresh than from cryopreserved gametes (30.8% vs. 8.1%, respectively). Finally, oocyte centrifugation was effective in obtaining karyoplasts with <5% of mitochondria.
CONCLUSION(S):
Cows can provide a suitable organism model to develop GVT technique in both research and clinical settings as well as in fertility preservation programs
Meat composition, from microscopy to chemistry by way of diagnostic imaging
Full text linkThe increasing demand of a real-time monitoring of food products has encouraged the application of non-invasive techniques. Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) proved to be very accurate and valuable tools in estimating body and carcass composition in farm animals.1 CT has been successfully used for the characterization of food Italian products such as salami, providing a precise evaluation of fat percentage, also assessing its spatial distribution.2 Manzocco and colleagues demonstrated that MRI has great potential in monitoring the evolution of dry curing in S. Daniele hams.3In our experience, helical CT proved to be a fast tool in the classification of different meat cuts, deriving from adult cow and destined for the preparation of aircured products as “lean meat” or “fat meat”, both in fresh and frozen samples.
Histological studies confirmed that CT clearly distinguishes adipose and connective tissue infiltration within muscles and that semi-quantitative analysis of infiltration degree can be achieved.
These data were further supported by the chemical analysis of meat samples corresponding to the same region of interest observed in both CT and histologic investigations; dry matter, crude proteins, crude fat and ash contents, calculated following standard international methods,4 varied in fact depending on the fat infiltrated extent, according with CT images. We finally observed that CT could be used in the evaluation of the same products at the end of ripening, without removing the outer envelope.
These results are important for beef and meat industrial processing sector, suggesting that CT could be employed as an on-line instrument in abattoir and dry-cured meat industry in classifying the products at the beginning of the manufacturing even they are frozen. Moreover, it might represent a rapid and non-invasive technique for quality check at the end of the production line and for the assignment of the most appropriate nutritional and commercial value to different products
Large-scale chromatin remodeling and DNA methylation in immature bovine oocyte during the later phase of growth and differentiation
No full textRecent advances in tissue engineering technology suggest its application in different medical fields, including periodontology. There are some reports of new non-enzymatic methods of isolating human gingival fibroblast for short-time cultivation in vitro to be used in autologous gingival augmentation. The aim of this study was to obtain a simple and established method of culturing human gingival fibroblasts. The authors developed a recurrent method that can be successfully used in autologous gingival augmentation
Gap junction-mediated communications regulate chromatin remodeling during bovine oocytes growth and differentiation through cAMP-dependent mechanism(s)
No full textOocyte development is characterized by impressive changes in chromatin structure and function in the germinal vesicle (GV) that are crucial in conferring to the oocyte meiotic and developmental competence. During oogenesis, oocyte and follicular cells communicate by paracrine and junctional mechanisms. In cow, cumulus-enclosed oocytes (CEOs) isolated from early antral follicles have uncondensed chromatin (GV0), functionally open gap junction (GJ)-mediated communications, and limited meiotic competence. The aim of the present study was to analyze the role of GJ communications on the chromatin remodeling process during the specific phase of folliculogenesis that coincides with the transcriptional silencing and the sequential acquisition of meiotic and developmental capability. CEOs were cultured in a follicle-stimulating hormone-based culture system that sustained GJ coupling and promoted oocyte growth and transition from GV0 to higher stages of condensation. When GJ functionality was experimentally interrupted, chromatin rapidly condensed, and RNA synthesis suddenly ceased. These effects were prevented by the addition of cilostamide, a phosphodiesterase 3 inhibitor, indicating that the action of GJ-mediated communication on chromatin structure and function is mediated by cAMP. Prolonging GJ coupling during oocyte culture before in vitro maturation enhanced the ability of early antral oocytes to undergo meiosis and early embryonic development. Altogether, the evidence suggests that GJ-mediated communication between germinal and somatic compartments plays a fundamental role in the regulation of chromatin remodeling and transcription, which in turn are related to competence acquisition
Large-scale chromatin morpho-functional changes during mammalian oocyte growth and differentiation
Full text linkMammalian oocyte development is characterized by impressive changes in chromatin structure and function within the germinal vesicle (GV). These changes are crucial to confer the oocyte with meiotic and developmental competencies. In cow, oocytes collected from early and middle antral follicles present four patterns of chromatin configuration, from GV0 to GV3, and its progressive condensation has been related to the achievement of developmental potential. During oogenesis, follicular cells are essential for the acquisition of meiotic and developmental competencies and communicate with the oocyte by paracrine and gap junction mediated mechanisms. We recently analyzed the role of gap junction communications (GJC) on chromatin remodeling process during the specific phase of folliculogenesis that coincides with the transcriptional silencing and sequential acquisition of meiotic and developmental capabilities. Our studies demonstrated that GJC between germinal and somatic compartments plays a fundamental role in the regulation of chromatin remodeling and transcription activities during the final oocyte differentiation, throughout cAMP dependent mechanism(s)
Large-scale chromatin structure and function changes during oogenesis : the interplay between oocyte and companion cumulus cells
No full textThe process of chromatin configuration remodeling within the mammalian oocyte nucleus or germinal vesicle (GV), which occurs towards the end of its differentiation phase before meiotic resumption, has received much attention and has been studied in several mammals. This review is aimed to highlight the relationship between changes in chromatin configurations and to both functional and structural modifications occurring in the oocyte nuclear compartment. During the extensive phase of meiotic arrest at the diplotene stage, the chromatin enclosed within the GV is subjected to several levels of regulation. Morphologically, the chromosomes lose their individuality and form a loose chromatin mass. Then the decondensed chromatin undergoes profound rearrangements during the final stages of oocyte growth in tight association with the acquisition of meiotic and developmental competence. Functionally, the discrete stages of chromatin condensation are characterized by different level of transcriptional activity, DNA methylation and covalent histone modifications. Interestingly, the program of chromatin rearrangement is not completely intrinsic to the oocyte, but follicular cells exert their regulatory actions through gap junction mediated communications and intracellular messenger dependent mechanism(s). With this in mind and since oocyte growth mostly relies on the bidirectional crosstalk with the follicular cells, experimental manipulation of large-scale chromatin configuration is discussed. Besides providing tools to determine the key cellular pathways involved in genome-wide chromatin modifications, the present findings will aid to the refinement of physiological culture systems that can have important implications in treating human infertility as well as managing breeding schemes in animal husbandry
- …
