Fertility of cryopreserved sperm in three bulls with different Robertsonian translocations.

The fertility of three bulls carrying different Robertsonian translocations (rob(1;29), rob(14;17) and rob(26;29)) was evaluated. Oocytes-cumulus complexes obtained from slaughterhouse-derived ovaries were matured and then fertilised in vitro with frozen/thawed seminal material from the above mentioned subjects, and from control bulls with normal karyotype. An assessment was first made of the concentration, vitality and acrosome integrity of the seminal material to be sure that possible differences in the results of the in vitro fertilisation experiments were not due to seminal material quality. The results of the experiments, evaluated by the percentage of cleaved embryos and blastocysts per cleaved embryo, indicated that the three bulls carrying Robertsonian translocations had similar fertilising power and semen qualitative parameters to the controls. These data suggest that neither gametogenesys impairment nor decreased spermatozoa fertilising capacity is responsible for the reduced fertility in bulls with Robertsonian translocations. What the data do confirm is that the observed in vivo hypofertility for karyologically abnormal bulls is mainly due to early embryonic mortality.

Transient transfection of porcine granulosa cells after 3D culture in barium alginate capsules.

Three-dimensional culture systems in barium alginate capsules can be employed to maintain primary granulosa cells in an undifferentiated state for almost 6 days. This is due to a self-organization of cells in a pseudofollicular structure. The transfection of primary granulosa cells is a necessary condition when employing these culture systems for several purposes, for example as an in vitro toxicity test or the development of oocytes or zygotes. In this work, the feasibility of two transient transfection techniques (liposome-mediated and electroporation) was assessed in primary porcine granulosa cells after a 6-day culture in an artificial extracellular matrix (barium alginate membrane). Human recombinant green fluorescent protein was chosen as a molecular readout, and protein expression was assessed after 48 hours from transfection. Liposome-mediated transfection gave low transfection levels, with increasing yields from 2 to 12 microgDNA/ml of medium; the maximum percentage (85.7%) was reached at 12 microgDNA/ml of medium. Electroporation-mediated transfection yields were higher: the best results (81.7% of transfected cells) were achieved with two 50V pulses and 12 microg/ml DNA. The application of a single or double pulse (50V) at 4 mgDNA/ml gave negligible results. These results indicate that primary granulosa cell cultured in barium alginate capsules can be transfected by electroporation with high transfection yields.

Boar semen controlled delivery system: storage and in vitro spermatozoa release.

Swine spermatozoa were encapsulated in barium alginate and protamine-barium alginate membranes to lengthen their preservation time and to provide a means of controlling their release. Precocious acrosome reactions and secondary anomalies were measured as indices of semen quality. These characteristics were observed for two forms of encapsulated spermatozoa when stored at 18 and 38 degrees C for 24 h and for semen diluted in a classical extender at both temperatures. The results indicate that encapsulation enhances semen preservation, providing protection against membrane damage upon dilution. The effect is even more evident at the higher temperature (38 degrees C), where cell metabolism is higher. An in vitro release test of spermatozoa showed a massive cell delivery from barium alginate capsules within 6 h, and a slow release from protamine-barium alginate capsules. The properties of spermatozoa 24 h after release did not differ from the semen stored at the same temperature in capsules, indicating that the release process does not impair semen quality.

A new centric fusion translocation in cattle: rob (13;19).

A new Robertsonian translocation has been found in cattle. A bull from Marchigiana breed (central Italy) was found to be a heterozygous carrier of a centric fusion translocation involving cattle chromosomes 13 and 19 according to RBA-banding and cattle standard nomenclatures. CBC-banding revealed the dicentric nature of this new translocation, underlining the recent origin of this fusion. In fact, both the bull's parents and relatives had normal karyotypes. In vitro fertilization tests were also performed in the bull carrying the new translocation, in two bulls with normal karyotypes (control) and in four other bulls carrying four different translocations.

[Cryopreservation of female gametes after the second meiotic division]. / Crioconservazione di gameti femminili dopo completamento della seconda divisione meiotica.

During the past few years, experimentation in the field of assisted fertilisation has been focused on the freezing of the female gamete. This technique would allow the ethical problems relating to embryo conservation to be resolved. Unfortunately, in spite of the continuous progress made in embryology, conventional freezing methods have proved lethal to ovocytes owing to the profound morphological and functional changes that take place caused by the low temperature and the toxic action of cryoprotective agents. These alterations include: the thickening of the pellucid zone, thus preventing fertilisation; the confluence of cytoplasmatic organules into vesicles and masses; the depolymerisation of the microtubular apparatus of the meiotic spindle and loss of its orientation towards the egg cell, leading to lack of fertilisation or in the event that fertilisation takes place, a high incidence of chromosomal alterations, such as polyploidy, which are incompatible with subsequent embryonal development. This study aimed to evaluate the possibility of eliminating part of these alterations, in particular those affecting the meiotic spindle, an element of central importance in the formation of the zygote. For this purpose, ovocytes matured in vitro were treated with ionomycin, a substance capable of activating the second meiotic division, and then frozen. The mechanism of action of ionomycin can be attributed to the depolarisation of the plasmatic membrane of the ovocyte, with an increased flow of calcium ions and inhibition of a protein that blocks the second meiotic division. The activation of the second meiotic division has enabled the authors to avoid damage to the meiotic spindle resulting from freezing and to obtain encouraging results in terms of the percentage of fertilisation and embryonal development after freezing, and the subsequent insemination of the ovocyte. Embryonal development ceased during the subsequent phases for reasons that are not yet clear. However, this study showed that severe cellular damage induced by freezing is attributable to alterations to the meiotic spindle that condition the later phases of fertilisation and embryonal development.