Playing polo during mitosis: PLK1 takes the lead.

Polo-like kinase 1 (PLK1), the prototypical member of the polo-like family of serine/threonine kinases, is a pivotal regulator of mitosis and cytokinesis in eukaryotes. Many layers of regulation have evolved to target PLK1 to different subcellular structures and to its various mitotic substrates in line with its numerous functions during mitosis. Collective work is starting to illuminate an important set of substrates for PLK1: the mitotic kinases that together ensure the fidelity of the cell division process. Amongst these, recent developments argue that PLK1 regulates the activity of the histone kinases Aurora B and Haspin to define centromere identity, of MPS1 to initiate spindle checkpoint signaling, and of BUB1 and its pseudokinase paralog BUBR1 to coordinate spindle checkpoint activation and inactivation. Here, we review the recent work describing the regulation of these kinases by PLK1. We highlight common themes throughout and argue that a major mitotic function of PLK1 is as a master regulator of these key kinases.

Effect of cholesterol on the motility and plasma membrane integrity of frozen equine spermatozoa after thawing.

The aim of the present study was to investigate the cryoprotectant properties of cholesterol after incorporation into the plasma membranes of equine spermatozoa. A cholesterol-methyl-beta-cyclodextrin complex was used to alter sperm plasma membrane cholesterol content. Ejaculates from six stallions were centrifuged in a non-fat skimmed milk glucose-sucrose extender (MK) or a modified Tyrode's medium (TALP). The sperm pellets were resuspended in the appropriate extender with or without added cholesterol (0.125 mmol cholesterol-methyl-beta-cyclodextrin complex l(-1)) and incubated at 24 degrees C for 15 min. After incubation, the aliquots were centrifuged and the sperm pellets were resuspended in lactose-EDTA-egg yolk freezing extender, frozen in static nitrogen vapour and stored at -196 degrees C. The straws were thawed and the motility and plasma membrane integrity of the spermatozoa were analysed. Addition of cholesterol to the incubation extenders improved the mean percentages of motile, progressively motile and rapidly motile spermatozoa in both the MK and TALP extenders containing cholesterol compared with extenders without cholesterol (P < 0.05). The percentage of spermatozoa with intact plasma membranes was higher in samples incubated in extenders containing cholesterol than in those without cholesterol (P < 0.05). The results of this study indicate that cyclodextrins can be used to incorporate cholesterol into equine sperm plasma membranes and that cholesterol incorporation imparts protection to the spermatozoa during cryopreservation.

Estudio terapéutico fase II: prospectivo no aleatorio, con interferón: alfa 2B recombinante en la infección del cuello uterino por virus papiloma humano (VPH) / Therapeutic study phase II: not aleatory prospective with recombinant interferon: alpha 2b in the cervix utery infections by papillomavirus human

El 20 por ciento del Cáncer Genital está asociado a la infección por Virus Papiloma Humano (VPH). Lograr un tratamiento para la infección por VPH del Cuello uterino. Ingresaron 14 pacientes (ptes) con enfermedad del Cuello Uterino (CU) por VPH, recurrente o recidivante, comprobada por biopsia dirigida en quienes habían fracasado los tratamientos convencionales conocidos. La edad estuvo comprendida entre los 19 y 40 años (a) en 78.5 por ciento de las pacientes. La Citología pre-tratamiento reveló 8/14 o 57,1 por ciento de las pacientes tenían infección por VPH. Con Colposcopia y biopsia dirigida del CU se obtuvo 100 por ciento de diagnóstico para VPH. Se usaron 3 x 10

Fertility comparison between breeding at 24 hours or at 24 and 48 hours after collection with cooled equine semen.

It has become a common practice in the equine breeding industry to send 2 insemination doses for breeding with transported cooled semen, one to be used for the initial insemination upon arrival, and the other to be held a second insemination the next day. One fertile stallion and 36 fertile mares were used to determine if breeding once with 1 dose of semen cooled for 24 h would improve fertility compared with breeding twice, 1 d apart, with half the dose of semen cooled for 24 h on the first day of breeding and half cooled for 48 h on the second day of breeding. Mares were given two intramuscular injections of 10 mg PGF2 alpha 14 d apart. Following the second injection, mares were teased with a stallion and their ovaries were scanned by transrectal ultrasonography daily. When a dominant follicle (> 35 mm diameter) was detected, 1500 units hCG were injected intravenously, and the mares were inseminated. Semen was collected in advance of anticipated breeding, mixed in nonfat dry milk solids-glucose extender to a concentration of 25 million sperm/mL, and placed in 2 commercial cooling containers for 24 or 48 h of storage prior to breeding. Mares were randomly assigned to 1 of 2 insemination treatment groups: 1) Group T1 (n = 18), in which mares were inseminated on the day of hCG injection with 500 million spermatozoa cooled for 24 h, or 2) Group T2 (n = 18), in which mares were inseminated on the day of hCG injection with 250 million spermatozoa cooled for 24 h, and again on the following day with 250 million spermatozoa cooled for 48 h. Pregnancy status was confirmed by transrectal ultrasonographic examination at 14 and 16 d after ovulation. Pregnancy rates were the same for both insemination treatment groups (12/18; 67%). There was no advantage to holding half of the insemination dose for rebreeding on the following day.

Comparison of three containers used for the transport of cooled stallion semen.

Three containers commonly used to transport cooled equine semen (Equitainer, ExpectaFoal and a Swedish-designed semen-transport container, previously called the Salsbro Box and now called Equine Express) were compared, using four ejaculates from each of three stallions. Each ejaculate was diluted to a spermatozoal concentration of 25 x 10(6)/ml with a nonfat dry milk-glucose extender containing amikacin sulfate (1 mg/ml) and potassium penicillin G (1000 units/ml). Extended semen was divided into three 40-ml aliquots for placement in each of the three semen-transport containers. The extended semen was stored in the containers for 24 h prior to analysis. Stored semen was warmed for 15 min at 37 degrees C, then video records of sperm motility were obtained for evaluation using a Hamilton-Thorne motility analyzer equipped with a stage warmer set at 37 degrees C. The temperature of 40-ml aliquots of semen extender stored in each container was also measured for 60 h using a copper-constantan thermocouple placed in the center of the stored samples. Intervals from onset of storage until sample temperature exceeded 10 degrees C during the warming phase were 27.5, 33.5 and 53 h, for the Expecta-Foal, Equine Express and Equitainer, respectively. Semen extender stored in the Equitainer compared most favorably to ideal cooling rates and storage temperatures published previously. Following a 24-h storage period, the mean percentages of motile, progressively motile, and rapidly motile spermatozoa, as well as the mean spermatozoal curvilinear velocity were similar (P > 0.05) among the three containers.