The proliferation inhibitory proteins p27(Kip1) and retinoblastoma are involved in the control of equine lymphocyte proliferation

Observations in early equine pregnancy clearly reveal maternal immune recognition of and response to the presence of the conceptus. Nevertheless, both maternal cellular and humoral responses appear ineffective in destroying the developing placenta and fetus in early pregnancy. Our previous studies had shown that the pre-conditioned medium generated from the culture of equine invasive trophoblast inhibited mitogen-induced lymphocyte proliferation and the expression of cytokine messenger RNA in vitro. Those findings also suggested that lymphocytes might have been halted in the G0/G1 phase of the cell cycle. To characterize the cell cycle and the intracellular mechanisms involved in the inhibition of lymphocyte proliferation, equine peripheral blood lymphocytes were cultured in the presence or absence of pokeweed mitogen (PWM) in fresh medium, or in medium pre-conditioned through cell culture of invasive trophoblast cells or fetal fibroblasts. Two-color flow cytometric analysis for bromodeoxyuridine (BrdU) incorporation by stimulated lymphocytes, and concomitant DNA staining with 7-amino-actinomycin D (7-AAD), indicated that a greater proportion of lymphocytes were found in the G0/G1 phase of the cell cycle when cultured in the invasive trophoblast cell pre-conditioned medium compared to controls. Analysis using carboxyfluorescein diacetate succinimidyl ester (CFSE) fluorescence intensity demonstrated that lymphocytes cultured in the presence of invasive trophoblast cell pre-conditioned medium had fewer cells going through division, but that those fewer cells sustained similar numbers of cell divisions as in control cultures. Hypophosphorylated retinoblastoma (Rb) protein expression was increased and p27Kip1 expression was maintained at higher levels in lymphocytes cultured in invasive trophoblast pre-conditioned medium compared to fresh medium. In agreement with these data, flow cytometric measurement of the Ki-67 protein expression in lymphocytes cultured in invasive trophoblast pre-conditioned medium was lower in comparison to controls. These findings suggest that the equine lymphocyte proliferation is at least partially regulated by the expression of proliferation inhibitory proteins such as p27Kip1 and hypophosphorylated Rb. These proteins seem to be important regulators of cell cycle transition between G1 and S phase in equine lymphocytes.     

Using “Uterine Index” to diagnose embryonic death in mares

Embryonic death plays an important role in infertility in mares, and most of embryonic mortality occurs at an early stage (before day 40) of pregnancy. Previous investigations focused on B-mode sonographic images to determine abnormal pregnancy; however, no study has provided a quantitative and objective method to diagnose embryonic death. Here we developed a new index, “Uterine Index,” using color Doppler sonography to describe alterations of uterine blood flow in physiological and pathological gestations during early gestation. Six Trotter mares were used in this study. The pregnancies were interrupted with a prostaglandin F2α (PGF_2α) analog (tiaprost) at days 25, 30, and 40. Three gestations were investigated in each stage. After the PGF_2α administration, these mares were examined every 8 hours until the embryonic vesicles were not visible on ultrasound. In the control group, three pregnancies were examined daily from days 12 to 60. The embryo size was measured in B-mode sonography, and the blood flow in uterine arteries was examined in Doppler ultrasound. The resistance index (RI) and uterine index (UI) were calculated. In the control group, the RI values of uterine artery were lower in pregnant side compared with that of the non-pregnant side from day 15 on, and the difference became greater as the pregnancy advanced (P < .05). The UI was close to 0 before week 3 and increased to approximately 10 after week 4. In the PGF_2α-treated group, the UI values reduced from pregnancy level to approximately 0. As early as 32 hours before embryonic death, we observed a significant difference of UI values between control and treated mares. On the contrary, the embryo size of treated mares was not different from that of normal mares. Through the analysis of all recorded UI values, we suggest that the UI values 10 and 5 are good values for distinguishing normal pregnancy (UI >10) from embryonic death (UI < 5). If the UI values are located between 10 and 5, a reexamination at intervals of 1 to 3 days is recommended. Our findings demonstrate that the UI is a useful method to diagnose and predict embryonic death in mares by providing reliable and objective information.     

谈如何使警犬技术的独特作用得到充分发挥

随着警犬技术自身不断地发展和完善,使用效益逐步提高,警犬技术在公安工作中的独特作用也日益明显,但其独特作用是否已经得到充分发挥了呢?笔者认为,目前我国警犬技术的作用距"充分发挥"还相差甚远.主要表现为:作为证据仍未得到法律的确认,参与侦办"大案"多、忽视了对"小案"的侦办,在各地区发挥的作用不均衡.究其原因,笔者认为主要有以下三个方面.     

Dietary effects on egg production,egg‐hatching rate and female life span of the tropical calanoid copepod Acartia bilobata

Copepods are crucial source of live feeds in the aquaculture industry. In particular, several species of the genus Acartia are considered optimal prey for fish larvae. The species Acartia bilobata has excellent potential for marine larvae culture, as it is easy for mass culture. This study investigated the effects of various algal diets on the egg production and egg‐hatching rate of A. bilobata. The results indicated that the single‐species diet Isochrysis galbana was the most supportive diet for A. bilobata egg production and female life span in all treatments (egg production: 23.85 ± 0.70 eggs female^?1 day^?1 and female life span: 18.00 ± 1.45 days). Nannochloropsis oculata and Tetraselmis chui treatments gave markedly lower egg production and female life span as both single‐species and multiple‐species diets. For the egg hatching‐rate experiment, except for the T. chui treatment, which yielded a considerably lower hatching rate than the other diets, the hatching rate was only slightly affected by the algal diets. These results confirm that A. bilobata, a tropical brackish‐water copepod species, develops rapidly at 28°C and can produce a large number of eggs; therefore, it has considerable potential for larvae culture.     

LEYMUS AEMULIS (NEVSKI) TZVEL., A NEW RECORD FROM WEST CHINA -- ITS MORPHOLOGICAL AND CYTOLOGICAL OBSERVATIONS

<正> Leymus aemulis (Nevski) Tzvel. is newly recorded in China. The morphology and cytology of this species were studied. It has single spikelet per node different from other Chinese species of Leymtis. The chremosome number is 2n=28. The chromosome pairing was analysed at metaphase Ⅰ. Meiotic configuration was 0.11 Ⅰ+13.95 Ⅱ. It indicated that this species is an allo-tetraploid.     

Real-time, very-long-baseline interferometry based on the use of a communications satellite

The Hermes satellite, a joint Canadian-American program, has been used to provide a communication channel between radio telescopes in West Virginia and Ontario, for very-long-baseline interferometry (VLBI). This system makes possible instantaneous correlation of the data as well as a sensitivity substantially better than that of earlier VLBI systems, by virtue of a broader observational bandwidth. With the use of a geostationary communications satellite it is possible to eliminate the tape recorders and the most troublesome part of the postobservational data processing. A further possibility is the development of a phase-coherent interferometer.     

Level of dietary energy during prepubertal growth and reproductive development of gilts.

Development of gilts that conceive early and continue to produce offspring is a primary objective of swine production. The objective of this study was to determine the degree of feed restriction during development required to optimize reproductive performance and efficiency in gilts. The effects that various patterns of growth had on reproductive development and performance of gilts through d 30 of gestation were investigated. At 13 wk of age and 41 kg BW, 192 white crossbred gilts were penned individually and assigned to receive 87.5%, 75%, 62.5%, and 50% of predicted ad libitum energy intake. The study was replicated in two seasons. At 25 wk of age, gilts were moved to group pens and allowed ad libitum access to feed, and estrous detection was initiated. Gilts were inseminated at first observed estrus and those recycling were remated. Post-mating gilts were fed 1.5x maintenance in stalls. Gilts that did not return to estrus 17 to 30 d after mating were slaughtered at 30 d of gestation. Reproductive tracts were collected and numbers of corpora lutea and live embryos were recorded. Feed restriction during development resulted in differences in BW and backfat thickness at the start of the breeding period and differences in feed intake during breeding. Gilts subjected to the greatest feed restriction during development consumed the greatest quantity of feed during breeding. Feed intake during breeding was associated with BW and backfat gain during breeding. The treatment group that entered breeding lightest and leanest (50% of predicted ad libitum intake) had the least number of days to first estrus, followed by the fattest, heaviest group (87.5% of predicted ad libitum intake). Treatment groups did not differ (P > 0.38) in ovulation rate or live embryo numbers. Significant relationships between quantity of GE consumed during development and variables considered important in reproductive development and performance were evident, such as BW and fatness at start of breeding and first detected estrus, and ovulation rate. Variation in dietary energy during the development period impacted many aspects of reproductive development and performance. However, coupling restricted energy intake during development with ad libitum intake during breeding negated many of the effects of feed restriction during the development period.