Effect of methotrexate exposure at late gestation on development of telencephalon in rat fetal brain

Pregnant rats were treated with 30 mg/kg of methotrexate (MTX) on gestation day (GD) 16, and fetal brains were examined time-dependently. On GD 20, the appearance of the telencephalon in the MTX group was different from that in the control group, and the major axis of the telencephalon of the MTX group was shortened, compared to that of the control group. In the sagittal section of the telencephalon in the MTX group on GD 20, histopathological findings of deformation and narrowing of the cerebral ventricle, the disturbance of the arrangement of the marginal cell layer of subventricular zone (SVZ) and thickening of telencephalic wall, cortical plate and ventricular zone (VZ)/SVZ were possibly attributable to neuronal migration disorders by MTX. Through all the experimental period, few pyknotic cells or TUNEL-positive cells were observed in the VZ/SVZ of the telencephalic wall and striatum in the control group. On the other hand, in the VZ/SVZ of the telencephalic wall and striatum in the MTX group, pyknotic cells or TUNEL-positive cells were observed on GD 17, and they increased significantly on GD18 and then decreased to the control levels from GD 19 onward. The phospho-Histone H3-positive rate decreased remarkedly in the VZ/SVZ of the telencephalic wall and striatum of the MTX group on GDs 17 and 18, compared to the control group, but they recovered on and after GD 19. These results suggested that there was a high possibility that development of the telencephalon in this period required strong folic acid.     

叶酸对圈养隆林黑山羊生长性能的影响研究

叶酸是水溶性B族维生素,一般认为山羊自身可合成,本文研究在圈养条件下饲料中添加叶酸对隆林黑山羊生长性能的影响效果。选择4月龄体况相近的平均体重为14kg左右健康生长期肉用隆林黑山羊母羊28只,采用单因素随机分组设计,随机分成4组,每组7只,分别在基础日粮中添加0mg/kg、1.5mg/kg、15mg/kg、45mg/kg(DM)的叶酸,进行饲养试验。结果表明,叶酸对山羊的生长速度和饲料转化率有较好的促进效果,在山羊日粮中添加45mg/kg(DM)的叶酸,其日增重比对照组提高19.2%,饲料转化率比对照组提高15.34%,在叶酸饲养试验中效果最佳。表明在日粮中添加叶酸对山羊有促生长作用。     

烟酸和不同水平叶酸对肉仔鸡生产性能的影响

试验选用1日龄艾维茵商品代白羽肉鸡210只,随机分成7组,每个处理组3个重复,每个重复10只鸡。处理Ⅰ组为对照组,处理Ⅱ、Ⅲ、Ⅳ组叶酸的添加水平分别为0.75、1.5和3.0 mg/kg;处理Ⅴ、Ⅵ、Ⅶ组烟酸的添加水平为60 mg/kg,叶酸的添加水平分别为0.75、1.5和3.0 mg/kg。于21日龄时,以重复为单位逐个称重,记录耗料量,计算料重比。结果表明,在21日龄时,与对照组相比,日粮中添加不同水平的叶酸均可显著提高肉仔鸡的日增重和日采食量,降低料重比（P<0.05）;添加60 mg/kg烟酸和不同水平叶酸可极显著提高肉仔鸡的日增重（P<0.01）。     

Preclinical evaluation of L-asparaginase and methotrexate administered at intermediate doses in dogs.

The role of L-asparaginase (L-ASP) in limiting signs of methotrexate (MTX) toxicosis was studied. Eight dogs were randomly allotted to 2 groups of 4 dogs. All dogs were given 400 IU of L-ASP/kg of body weight IM, on day 1. On day 10, group-1 dogs were given 3 mg of MTX/kg, IV, and group-2 dogs were given 6 mg of MTX/kg, IV. All dogs were given 400 IU of L-ASP/kg, IM, 24 hours later (on day 11). One group-2 dog was euthanatized on day 16 because of severe gastrointestinal signs that were unresponsive to treatment. A second dose of MTX, identical to that given on day 10, was given on day 20 to each surviving dog, followed by L-ASP on day 21. On day 67, the 7 surviving dogs were given 3 mg of MTX/kg, IV. Adverse reactions observed were vomiting, diarrhea, and weight loss. Gastrointestinal side effects of MTX were not attenuated with L-ASP and would be a serious limitation to use of MTX administered at an intermediate dose in the treatment of lymphoma in dogs.     

叶酸对超早期断奶宫内发育迟缓仔猪肝脏结构和细胞凋亡相关基因表达的影响

本试验旨在研究饲粮添加不同水平叶酸对超早期断奶宫内发育迟缓(IUGR)仔猪肝脏结构和细胞凋亡相关基因表达的影响。选取24头14日龄断奶、平均体重(2.79±0.34)kg的"杜×长×大"三元杂交仔公猪,随机分为3个处理,分别饲喂在基础饲粮中添加0、5和10 mg/kg叶酸的试验饲粮,每个处理8个重复,每个重复1头猪。试验期21 d。结果表明:1)饲粮添加叶酸对35日龄仔猪血清葡萄糖浓度无显著影响(P>0.05),添加5和10 mg/kg叶酸分别显著(P<0.05)和极显著(P<0.01)降低了血清甘油三酯浓度。2)饲粮添加5 mg/kg叶酸能显著降低肝细胞直径(P<0.05)。3)饲粮添加5 mg/kg叶酸显著提高了肝脏B细胞淋巴瘤蛋白2(Bcl-2)的基因表达量(P<0.05),极显著降低了Bcl-2相关X蛋白(Bax)和促凋亡相关基因肿瘤蛋白53(p53)的基因表达量(P<0.01);饲粮添加10 mg/kg叶酸,Bax和p53的基因表达量分别极显著(P<0.01)和显著(P<0.05)地降低了。4)饲粮添加叶酸对肝脏毛细血管扩张性共济失调症突变基因(ATM)、脱嘌呤嘧啶核酸内切酶1(APE-1)基因和一碳单位代谢关键酶编码基因的表达无显著影响(P>0.05)。结果提示,饲粮补充一定水平的叶酸有助于改善早期断奶IUGR仔猪35日龄时肝脏结构和细胞凋亡相关基因Bcl-2、Bax和p53的表达;本试验条件下,饲粮添加5 mg/kg叶酸效果较好。     

妊娠期添加叶酸对新生仔猪肝脏抗氧化能力和基因表达影响

试验选用24头大约克母猪,随机分为2个处理组,每组12个重复,研究妊娠期添加叶酸对新生仔猪肝脏抗氧化能力及其与叶酸代谢相关基因表达量的影响。对照组饲喂基础日粮(叶酸1.3 mg/kg),基础日粮为典型的玉米-豆粕型日粮,在基础日粮中添加叶酸构成处理组日粮(叶酸30 mg/kg),试验从母猪配种开始直至分娩。结果表明:妊娠期间增加母猪叶酸摄入量显著提高仔猪血清叶酸含量(P<0.01),极显著降低血清同型半胱氨酸含量(P<0.01)。叶酸添加组仔猪肝脏中总抗氧化能力(P<0.05)、谷胱甘肽过氧化物酶(P<0.05)和总超氧化物岐化酶活力(P<0.05)显著高于对照组。仔猪肝脏丙二醛和一氧化氮含量在添加叶酸之后显著下降(P<0.05)。添加叶酸显著提高仔猪肝脏中丝氨酸羟甲基转移酶基因表达量(P<0.05),下调T-蛋白基因mRNA水平(P<0.05)。由此可见,通过母体添加叶酸可显著改善仔猪肝脏抗氧化功能,并影响叶酸代谢相关基因表达量。     

Effect of folic acid supplements on homocysteine concentration in plasma of gestating sows.

An experiment comprising 19 German Landrace sows was established to evaluate the effect of folic acid supplements (10 mg/kg concentrate) on homocysteine and folic acid concentration in plasma and serum, respectively, of highly pregnant sows as compared to an unsupplemented control (basal diet contained 0.62 mg folic acid/kg concentrate). Blood samples were taken between day 75 and 110 of gestation for homocysteine analysis and on day 100 of gestation for folic acid determination. Due to the folic acid supplements serum folic acid concentration increased significantly (104 nmol/l in controls and 140 nmol/l in supplemented sows). In contrast, homocysteine concentration in the plasma was not significantly influenced by folic acid supplements (16.6 mumol/l in controls and 15.2 mumol/l in supplemented sows). Further investigations seem to be necessary to clarify the physiology of homocysteine metabolism in swine.     

2-Bromopropane induced germ cell apoptosis during spermatogenesis in male rat

2-Bromopropane (2-BP) causes testicular toxicity in humans and rats. However, the germ cell degeneration of testicular toxicity by 2-BP has not been understood. 2-BP at doses of 135, 405, and 1,355 mg/kg/day was daily injected subcutaneously into Sprague-Dawley rats for 28 days. At the dose of 1,355 mg/kg/day, 2-BP significantly decreased the weights of body and testes, eipididymis, seminal vesicle, and prostate, as well as daily sperm production. Atrophy of seminiferous tubules accompanied with degeneration of germ cells such as spermatogonia, spermatocytes, and elongated spermatids was observed in the testes of rats exposed to the 405 mg/kg/day and 1,355 mg/kg/day of 2-BP. TUNEL-positive germ cells were appeared in the 405 and 1,355 mg/kg/day of 2-BP-treated groups. In addition, ultrastructure alterations of apoptotic germ cells were observed by the electron microscopy study. Dead elongated spermatids were observed at 1,355 mg/kg/day after 28 days exposure. These results suggest that 2-BP impair spermatogenesis may result from apoptotic germ cell death.     

Measurement of the three-axis vibration,temperature, and relative humidity profiles of commercial transport trailers for pigs

The objective of this study was to collect and interpret three-axis acceleration, temperature, and relative humidity data from six locations within commercial transport trailers shipping market-weight pigs. Transport was observed in Kansas (n = 15) and North Carolina (n = 20). Prior to loading, three-axis accelerometers were affixed to six locations on the trailers: top fore (TF), top center (TC), top aft (TA), bottom fore (BF), bottom center (BC), and bottom aft (BA) compartments. Data were post-processed to calculate root-mean-square (RMS) accelerations and vibration dose values (VDV) in the vertical direction and the horizontal plane. These values were compared with exposure action values (EAV) and exposure limit values (ELV), vibration levels deemed uncomfortable and potentially dangerous to humans. Additionally, RMS and VDV were compared among the trailer compartments. The vertical RMS accelerations for all compartments exceeded the EAV for loads measured in Kansas, and for the majority of the compartments measured in North Carolina. Many compartments, specifically the BA compartment from all trips, exceeded the vertical ELV. Regardless of where the data were collected, fewer compartments exceeded the EAV in the horizontal orientation. Only BA compartments exceeded the ELV in the horizontal orientation. There were Area × Level interactions for vertical and horizontal RMS and VDV (P < 0.01). The BF compartment had a greater vertical RMS value than the TF, TC, and BC (P < 0.02) compartments, but did not differ (P = 0.06) from the TA compartment. The vertical RMS of the TA compartment did not differ from the TF, TC, and BC compartments (P > 0.13). The BF compartment had a greater (P = 0.02) vertical VDV value than the TC location, but did not differ from the other locations (P > 0.16). All other locations did not differ in vertical VDV (P > 0.12). The BF compartment had greater horizontal RMS than the TC and TA compartments (P < 0.01), but did not differ from TF and BC compartments (P > 0.12). All other compartments did not differ in horizontal RMS (P > 0.34). All compartments, aside from the BA compartment, did not differ in horizontal VDV (P > 0.19). Vibration analyses indicated the BA compartment had the greatest vertical and horizontal vibrations and a large percentage of the compartments exceed the EAV and ELV, which indicated pigs may have experienced uncomfortable trips that could cause discomfort or fatigue.     

Differentiation of stem progenitor CD9/SOX2-positive cells is promoted with increased prolactin-producing and endothelial cells in the pituitary

Sex-determining region Y-box 2 (SOX2)-positive cells are stem/progenitor cells in the adenohypophysis, comprising the anterior and intermediate lobes (AL and IL, respectively). The cells are located in the marginal cell layer (MCL) facing Rathke’s cleft (primary niche) and the parenchyma of the AL (secondary niche). We previously demonstrated in vitro that the tetraspanin superfamily CD9 and SOX2 double-positive (CD9/SOX2-positive) cells in the IL-side MCL migrate to the AL side and differentiate into hormone-producing and endothelial cells in the AL parenchyma. Here, we performed in vivo studies to evaluate the role of IL-side CD9/SOX2-positive cells in pregnancy, lactation, and treatment with diethylstilbestrol (DES; an estrogen analog) when an increased population of prolactin (PRL) cells was observed in the AL of the rat pituitary. The proportions of CD9/SOX2-, CD9/Ki67-, and PRL/TUNEL-positive cells decreased in the primary and secondary niches during pregnancy and DES treatment. In contrast, the number of CD9/PRL-positive cells increased in the AL-side MCL and AL parenchyma during pregnancy and during DES treatment. The proportion of PRL/Ki67-positive cells increased in the AL-side MCL and AL parenchyma in response to DES treatment. Next, we isolated CD9-positive cells from the IL-side MCL using an anti-CD9 antibody. During cell culture, the cells formed free-floating three-dimensional clusters (pituispheres). Furthermore, CD9-positive cells in the pituisphere differentiated into PRL cells, and their differentiation potential was promoted by DES. These findings suggest that CD9/SOX2-positive cells in the IL-side MCL may act as adult stem cells in the AL parenchyma that supply PRL cells under the influence of estrogen.     

雏鸡叶酸需要量的试验观察

10 0只海兰商品代 1月龄母雏 ,饲以基础日粮。随机分为 5组。A组作为对照组 ,B、C、D和E组分别添加 0 4、 0 5、 0 6、 1 0mg/kg叶酸(其他元素按标准自配 )。试验期 6周。结果表明 :随叶酸含量的增加 ,羽毛色泽亮丽 ,死亡率减少且体重有显著性增加。雏鸡正常叶酸需要量在0 7mg/kg以上。     

Effect of methotrexate on cerebellar development in infant rats

Six-day-old rats were treated intraperitoneal injections with methotrexate 1 mg/kg, and the cerebellum was examined. Both the length and width of the vermis decreased in the methotrexate-treated group instead of the control from 4 day after treatment (DAT) onward. A significant reduction in the width of the external granular layer was detected on 2 and 3 DAT in the methotrexate group. By 4 DAT, the width of the external granular layer of the methotrexate group was indistinguishable from the control, and by 8 DAT, it was greater than that of the control. The molecular layer of methotrexate group on 8 and 15 DAT was thinner than that of the control. On 1 DAT, in the methotrexate group, there were many TUNEL and cleaved caspase-3-positive granular cells throughout the external granular layer, and they decreased time-dependently. On 1 DAT, in the methotrexate group, phospho-histone H3-positive cells in the external granular layer were fewer than in the control and tended to increase on 2–4 DAT. The p21-positive-rate of the external granule cells in the MTX group was higher than in the control on 1–4 DAT. These results suggested that methotrexate exposure on postnatal day 6 induces a delay, slowing in the migration of external granular cells to the inner granular layer, attributed to decrease or inhibition in the production of external granular cells that had arisen from apoptosis and the decrease in cell proliferative activity, resulting in cerebellar hypoplasia.     

Chemical study of body organs in papular dermatitis in fattened pigs

In twenty fattened pigs with papular dermatitis (PD) and in seventeen pigs with no skin lesions (K),--the pigs had the live weight from 95 to 105 kg and came from a D. large fattening house situated in a region with extensive mining (lignite extraction)--we analyzed the skin, muscle, kidneys and liver for the contents of chemical elements (zinc, copper, manganese, lead, cadmium, mercury, chromium) and aflatoxin B1. In pancreas we analyzed only the content of aflatoxin B1. In comparison with the K group, the pigs with PD had in the skin the higher contents of zinc (PD 15.7 +/- 7.1 mg per kg, K 10.1 +/- 1.3 mg per kg, P less than 0.05) and aflatoxin B1 (PD 3.18 +/- 1.53 micrograms per kg, K 1.56 +/- 0.49 microgram per kg, P less than 0.05); in the muscle the higher contents of zinc (PD 30.2 +/- 7.6 mg per kg, K 23.8 +/- 5.4 mg per kg, P less than 0.05), of lead (PD 0.48 +/- 0.31 mg per kg, K 0.25 +/- 0.28 mg per kg, P less than 0.05) and copper (PD 3.19 +/- 3.11 mg per kg, K 0.98 +/- 0.41 mg per kg, P less than 0.01); in the kidneys the higher contents of lead (PD 0.96 +/- 0.75 mg per kg, K 0.26 +/- 0.34 mg per kg, P less than 0.01), cadmium (PD 0.38 +/- 0.14 mg per kg, K 0.26 +/- 0.20 mg per kg, P less than 0.05), manganese (PD 1.14 +/- 0.04 mg per kg, K 0.94 +/- 0.42 mg per kg, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

氮、磷、钾、钙对香水百合生长及叶片养分含量的影响

以盆栽香水百合为试验材料,采用氮、磷、钾、钙四因素四水平L₁₆(4⁴)正交试验设计方法,研究了不同肥料配比对香水百合株高、叶片数、叶面积、叶绿素和叶片中氮、磷、钾、钙含量变化的影响,旨在揭示香水百合需肥规律,为其规范化栽培提供依据。结果表明,1)氮肥对株高、叶面积、叶绿素影响显著,基本呈极显著正相关,氮肥为300 mg/kg时株高、叶片数、叶面积和叶绿素均最高;磷肥、钙肥与株高、叶片数、叶面积、叶绿素呈正相关;磷肥100～150 mg/kg、钾肥150 mg/kg、钙肥120 mg/kg时叶面积、叶绿素最高。2)叶片中氮、磷、钾、钙养分含量均呈先升高后下降的变化趋势,在现蕾期或初花期达到最高,现蕾期后不同处理间叶片养分含量差异显著。氮肥200～300 mg/kg、磷肥100 mg/kg、钾肥0～300 mg/kg时四者含量均最高。3)综合考虑各因素,最佳配比组合为氮300 mg/kg、磷100 mg/kg、钾150 mg/kg、钙120 mg/kg,该处理的香水百合生长状况最佳,株高增长快,叶片质量高,且叶中养分含量高,叶片磷、钾、钙积累持续时间长。     

Pharmacokinetics of low-dose methotrexate in horses

This study aimed to investigate both the pharmacokinetic behavior and tolerance of methotrexate (MTX) in horses to design a specific dosing regimen as a new immunomodulatory drug for long-term treatment. To determine the primary plasma pharmacokinetic variables after single intravenous, subcutaneous or oral administration, six horses were administered 0.3 mg/kg MTX in a crossover design study. After a 10-week washout, MTX was administered subcutaneously to three of the six previously treated horses at a dose of 0.3 mg/kg once per week for 3 months. In both studies, MTX and metabolite concentrations were measured using LC-MS/MS. The absolute bioavailability of MTX was 73% following subcutaneous administration but less than 1% following oral administration. The plasma clearance was 1.54 ml min⁻¹ kg⁻¹ (extraction ratio = 2%). After 24 hr, plasma concentrations were below the LOQ. No adverse effects were noted except for a moderate reversible elevation in liver enzymes (GLDH). With regards to the main metabolites of MTX, very low concentrations of 7-hydroxy-MTX were found, whereas polyglutamated forms (mainly short chains) were found in red blood cells. A subcutaneous dose of 0.2 mg kg⁻¹ week⁻¹ may be safe and relevant in horses, although this has yet to be clinically confirmed.     

Survival rate and development of fetuses during the first 30 days of gestation after folic acid addition to a swine diet

At weaning, 162 sows were assigned randomly to six treatments (27 in each treatment) according to a 2 X 3 factorial arrangement: two levels of supplementary folic acid (0 and 5 mg/kg of diet) and three treatments to stimulate ovulation (none, flushing and pregnant mare serum gonadotropin [PMSG] injection). All sows were mated twice within 7 d after weaning. Of the 162 animals originally selected, 123 sows were pregnant and used in this trial. The flushing treatment consisted of allowing sows ad libitum access to feed from the day after weaning through the 1st day of behavioral estrus, whereas control animals received 2.4 kg of feed daily. The hormonal treatment consisted of one i.m. injection of 1,250 IU of PMSG the day after weaning. The commercial-type diet used as the control was computed to contain .6 mg folates per kilogram. Folic acid supplementation elevated (P less than .001) serum folates between weaning and 30 d of gestation. Fetuses of sows fed the diet supplemented with folic acid had a higher (P less than .05) total protein concentration than fetuses of control sows, whereas RNA and DNA concentrations and protein:DNA ratio were not affected. The PMSG treatment elevated (P less than .05) ovulation rate, whereas the flushing or folic acid treatments had no effect on this trait. The addition of 5 mg/kg folic acid to the commercial-type diet improved (P less than .05) the survival rate of fetuses during early gestation and tended (P = .096) to increase the number of fetuses presumably living at 30 d of gestation when this treatment was associated with high ovulation rate.(ABSTRACT TRUNCATED AT 250 WORDS)     

Megaloblastic erythropoiesis and tissue depletion of folic acid in the cat

Dietary requirement for folic acid was shown in the cat. Folic acid deficiency was produced by feeding young cats a deficient diet (0.125 mg of total folate/kg of dry weight by analysis) for 22 weeks. The folic acid-deficient cats grew normally, but had reduced plasma, red blood cell, and liver folate concentrations in comparison with those concentrations in cats fed a control diet (1.36 mg of total folate/kg).. Urinary excretion of formiminoglutamic acid was increased in all deficient diet cats 24 hours after L-histidine injection. Erythroblasts in bone marrow smears from folic acid-deficient cats were megaloblastic; they showed abnormal nuclear chromatin patterns and had nuclear-cytoplasmic asynchronism.     

N -ethyl- N -nitrosourea induces retinal photoreceptor damage in adult rats

Seven-week-old male Lewis rats received a single intraperitoneal injection of N-ethyl-N-nitrosourea (ENU) (100, 200, 400 or 600 mg/kg), and retinal damage was evaluated 7 days after the treatment. Sequential morphological features of the retina and retinal DNA damage, as determined by a TUNEL assay and phospho-histone H2A.X (γ-H2AX), were analyzed 3, 6, 12, 24 and 72 hr, 7 days, and/or 30 days after 400 mg/kg ENU treatment. Activation of the nuclear enzyme poly (ADP-ribose) polymerase (PARP) was analyzed immunohistochemically by poly (ADP-ribose) (PAR) expression in response to DNA damage of the retina. All rats that received ≥ 400 mg/kg of ENU developed retinal degeneration characterized by the loss of photoreceptor cells in both the central and peripheral retina within 7 days. In the 400 mg/kg ENU-treated rats, TUNEL-positive signals were only located in the photoreceptor cells and peaked 24 hr after ENU treatment. The γ-H2AX signals in inner retinal cells appeared at 24 hr and peaked at 72 hr after ENU treatment, and the PAR signals selectively located in the photoreceptor cell nuclei appeared at 12 hr and peaked at 24 hr after ENU treatment. However, degeneration was restricted to photoreceptor cells, and no degenerative changes in inner retinal cells were seen at any time points. Retinal thickness and the photoreceptor cell ratio in the central and peripheral retina were significantly decreased, and the retinal damage ratio was significantly increased 7 days after ENU treatment. In conclusion, ENU induced retinal degeneration in adult rats that was characterized by photoreceptor cell apoptosis through PARP activity.     

Effects of Maternal Folic Acid Supplementation on Hepatic Apoptosis-Related Gene Expressions between Intrauterine Growth Restriction and Normal Body Weight Piglets

Intrauterine growth retardation （IU- GR） causes significantly negative effects on the meth- ylation status of genes related to cell apoptosis com- pared with normal body weight （NBW） piglets. Thus, the objective of the present study was to exam- ine the effects of maternal dietary folic acid supple- mentation on genes expression profile for hepatic ap- optosis in IUGR and NBW piglets. Twenty four York- shire gilts were allocated randomly to one of the two diets ： control （ C, folic acid 1.3 mg/kg） or folic acid supplementation （ FS, folic acid 30 mg/kg） after mat- ing. Gene expressions in liver samples were deter- mined and revealed that the mRNA expressions of p53 ,BCL-2 associated X protein （Bax）, and Cyclin- dependent kinase inhibitor 1A （CDKN1A） were up-regulated in IUGR piglets compared with NBW pig- lets fed C diets,but could be reversed by maternal fo- lic acid supplementation. The expressions of vascular endothelial growth factor （VEGF）, Serine-protein Ki- nase-Ataxia Telangiectasia Mutated （ATM） ,and Cad- herin-associated protein-beta-catenin 1 （ CTNNB1 ） were influenced by maternal folic acid supplementa- tion significantly, but were not influenced by birth weight. Expression of p53 binding protein-MDM-2 （ MDM-2 ） remained unchanged. In conclusion, these results demonstrated that maternal folic acid supple- mentation could exert positive effects on genes related to apoptosis in IUGR and NBW piglets, which might facilitate their postnatal health and growth perform- alice.     

河北片麻岩山区核桃×苜蓿模式早期细根分布特征

以河北片麻岩山区退耕地核桃(Juglans Regia)×苜蓿(Medicago sativa)模式为研究对象,采用挖掘取样法,研究了果草复合系统早期细根根系密度的空间分布特征,并比较分析了单作和间作模式下核桃细根分布的差异。结果表明:间作模式下核桃细根根系在垂直方向和水平方向上均呈现"低高低"的二次多项式分布,集中分布于20~60cm(垂直)、10~80cm(水平);苜蓿细根在垂直方向和水平方向上分布分别呈现负指数型和指数型分布,集中于0~30cm(垂直)、110~150cm(水平);在垂直深度0~20cm和水平距离100~150cm范围内,苜蓿核桃相对重叠比大于1,苜蓿根系占据主导地位,核桃根系则在较深垂直空间和较近林带具有明显优势;与核桃单作模式相比,果草间作模式下核桃细根从量上有所减少,在垂直方向上分布变深,在水平方向上亦有所下降。核桃苜蓿间作模式下细根分布具有一定的交织区域,存在竞争。