Developmental ability of oocytes retrieved from Meishan neonatal ovarian tissue grafted into nude mice

Ovarian xenografting makes it possible to obtain oocytes with fertilization ability from immature pigs of Western breeds. In this study, we applied these methods to the Meishan, an indigenous Chinese pig breed, and investigated the developmental competence of oocytes grown in their neonatal tissue after grafting into nude mice. First, mice harboring neonatal ovarian tissue were infused with follicle stimulating hormone (FSH) (62.5 U/ml) for 13 days starting at 10, 30, and 60 days after vaginal opening (D10‐, D30‐, and D60‐FSH groups, respectively). Development of antral follicles and their oocytes was most enhanced in the D60‐FSH group. For the next step, we examined the in vitro maturation ability of the oocytes recovered from host mice after infusion with FSH at a dose of 62.5 U/ml or 125 U/ml (FSH‐62.5 or ‐125 group) for 13 days starting at 60 days after vaginal opening. Many more oocytes with maturation ability were obtained from the FSH‐125 group. The FSH‐125 mature oocytes were fertilized in vitro, as shown by formation of male and female pronuclei, but did not reach the blastocyst stage. These results indicate that Meishan neonatal ovaries are able to produce oocytes with fertilization ability after being grafted into nude mice.     

Factors influencing the loss of forest cover in bangladesh: An analysis from socioeconomic and demographic perspectives

Some studies have attributed forest shrinkage to population growth, economic development, conversion of forest land to agricultural use and harvesting of trees for timber and fuelwood. But the statistical support for these hypotheses is not strong. This paper attempts to test the above hypotheses statistically in the case of Bangladesh. Factor analysis extracted 4 important factors—(a) exploitation of forests for timber, fuelwood, tea, and shrimp production, (b) demographic pressure in agriculture, (c) economic development, and (d) expansion of crop lands—as causes of deforestation. The statistical test supports the hypotheses that the exploitation of forests for timber, fuelwood, tea and shrimp production, and conversion of forests to crop lands have a negative influence on forest cover. Economic development and demographic pressure in agriculture are also negatively correlated with forest cover. Results of regression analysis show the conversion of forests to agricultural land is the most important cause of deforestation. Other important causes, in order of their relative importance, are the relative price of forest products, population growth, economic development, demographic pressure in agriculture, increasing production of shrimps, export of tea and shrimps, increasing production of timber and fuelwood, and expansion of tea lands. The statistical tests support the above relationships.     

Plasma concentrations of inhibin A in cattle with follicular cysts: relationships with turnover of follicular waves and plasma levels of gonadotropins and steroid hormones

We investigated the profiles of circulating levels of inhibin A and total inhibin in beef cows with follicular cysts in relation to the patterns of follicular development and circulating gonadotropins and steroid hormones. Turnover of follicular waves was monitored in five cows every 2 days for 70 days from 10 days after detection of estrus without ovulation. The mean interwave intervals were 19.6 ± 1.0 days (n = 18 waves with cysts from the five cows). Circulating levels of inhibin A were approximately 170 pg/ml before emergence of follicular waves with cysts and increased (P < 0.05) concomitantly with follicle emergence. High concentrations of inhibin A (greater than 300 pg/ml) were noted for 7 days during the growth phase of cystic follicles, but inhibin A levels decreased gradually when development of the cysts reached a plateau. This profile of inhibin A was similar to those of total inhibin and estradiol, but was inversely related to the changes in plasma FSH concentrations. LH pulse frequency and mean concentrations of LH in cows with cysts were higher than those observed in the luteal phase of normal cyclic cows. These results indicate that the capacity to secrete inhibin, as well as estradiol, is maintained in cystic follicles, the growth of which is extended by LH secretion at levels greater than those seen in the normal luteal phase. Inhibin A plays an important role in the extension of interwave intervals by suppressing recruitment of a new cohort of follicles.     

Oncolytic reovirus synergizes with chemotherapeutic agents to promote cell death in canine mammary gland tumor

The oncolytic effects of reovirus in various cancers have been proven in many clinical trials in human medicine. Oncolytic virotherapy using reovirus for canine cancers is being developed in our laboratory. The objective of this study was to examine the synergistic anti-cancer effects of a combination of reovirus and low doses of various chemotherapeutic agents on mammary gland tumors (MGTs) in dogs. The first part of this study demonstrated the efficacy of reovirus in canine MGTs in vitro and in vivo. Reovirus alone exerted significant cell death by means of caspase-dependent apoptosis in canine MGT cell lines. A single injection of reovirus impeded growth of canine MGT tumors in xenografted mice, but was insufficient to induce complete tumor regression. The second part of this study highlighted the anti-tumor effects of reovirus in combination with low doses of paclitaxel, carboplatin, gemcitabine, or toceranib. Enhanced synergistic activity was observed in the MGT cell line treated concomitantly with reovirus and in all the chemotherapeutic agents except toceranib. In addition, combining reovirus with paclitaxel or gemcitabine at half dosage of half maximal inhibitory concentration (IC₅₀) enhanced cytotoxicity by activating caspase 3. Our data suggest that the combination of reovirus and low dose chemotherapeutic agents provides an attractive option in canine cancer therapy.     

Quantitative real‐time PCR monitoring of Escherichia coli and Clostridium perfringens with oral administration of Lactobacillus plantarum strain Lq80 to weaning piglets

Levels of fecal or intestinal lactobacilli, Escherichia coli and Clostridium perfringens, and the prevalence of clostridial alpha toxin gene and heat‐stable toxin (ST) gene of enterotoxigenic E. coli (ETEC) were monitored in weaned piglets before (day 0) and during (days 7, 14, and 21) the administration of Lactobacillus plantarum strain Lq80. Lactobacilli were enumerated in a culture‐dependent method. The remainders were determined by quantitative real‐time PCR. In this quantitative real‐time PCR method, the detection limit was proved to be as low as 10³ cells/g feces or intestinal contents. Number of lactobacilli increased from day 0 to day 7 (P < 0.05), to day 14 (P < 0.05), and to day 21 (P = 0.07) in the Lq80‐administered group. L. plantarum contributed to as low as 10% of the lactobacillal population in the Lq80‐administered group. The number of E. coli and C. perfringens, and the prevalence of alpha toxin gene in feces or intestinal contents of the Lq80‐administered group decreased, at least in the first week of the postweaning period. Oral administration of L. plantarum strain Lq80 can stimulate the growth of indigenous lactobacilli and decrease ST‐producing ETEC and C. perfringens in the intestine of postweaning piglets.     

Retrospective analysis of the efficacy of controlled internal drug release in follicular cysts in an embryo donor beef herd

We investigated the efficacy of a controlled internal drug release (CIDR) device in the reproductive management of an embryo donor beef herd. Superovulation of embryo donors was routinely induced by a combination of FSH and prostaglandin F(2)alpha analogue (PGF(2)alpha) at intervals of a few months, and after embryo recovery estrus of the donors was synchronized with PGF2(2)alpha. Between 1996 and 1998, approximately 20% of donors were diagnosed as having follicular cysts every year. Twenty-eight cases of follicular cysts recorded between 1997 and 1998 were treated with a CIDR device for 14 days to evaluate the efficacy of CIDR in resolving follicular cysts in donor herds. Initial recovery was defined as the occurrence of ovulation with estrous behavior and subsequent formation of a corpus luteum after removal of the CIDR. Initial recovery was recognized in all cases (n=28). Follicular cysts did not recur after repeated embryo recovery in 64% of the initially recovered donors, but in 36% of affected donors cysts recurred after the next embryo recovery. Subsequently, with a CIDR device instead of PGF(2)alpha, we synchronized estrus after embryo recovery in the same herd from 1999 to 2000, to investigate the ability of CIDR to prevent the initiation of follicular cysts. Of the donors used between 1999 and 2000, approximately 30% had a history of follicular cysts. Use of CIDR for estrous synchronization after embryo recovery lowered the incidence of follicular cysts to 3% in 1999 and 0% in 2000. Treatment with CIDR proved effective at resolving follicular cysts in the embryo donor beef herd and enabled re-use of donors affected with follicular cysts. CIDR is also likely to be efficacious in lowering the occurrence of follicular cysts in donor herds when it is used for estrous synchronization after embryo recovery.     

Identification and validation of a quantitative trait locus associated with wheat yellow mosaic virus pathotype I resistance in a Japanese wheat variety

Yellow mosaic disease, caused by wheat yellow mosaic virus (WYMV), is one of the most serious diseases of winter wheat (Triticum aestivum L.) in Japan. The three pathotypes of WYMV are distributed in different geographical areas: pathotype I is found mainly in western and central Japan (Kanto), pathotype II in northern Japan (Tohoku and Hokkaido) and pathotype III on the southern island of Japan (Kyushu). A total of 246 doubled‐haploid (DH) lines, derived from a cross between ‘Yumechikara’ (resistant) and ‘Kitahonami’ (susceptible), were evaluated for 2 years for their resistance to WYMV pathotype I. A single major quantitative trait locus, Q.Ymym, mapping to chromosome 2D was associated with resistance to pathotype I in ‘Yumechikara’. This is the first time a QTL responsible for pathotype I resistance has been identified. Fine mapping of Q.Ymym indicated that it was on a tight linkage block originating from ‘Yumechikara’, and the markers associated with this block will accelerate the development of varieties resistant to WYMV pathotype I.