Adipose tissue development in the fetal pig examined using monoclonal antibodies

Two anti-adipocyte monoclonal antibodies (MAbs: AD-1 and AD-2) have been used to study the development of dorsal s.c. adipose tissue in fetuses from 50 to 110 d of gestation. Immunofluorescent staining of cryostat sections with each antibody revealed antigen-positive cells in fetal s.c. mesenchyme prior to lipid deposition. Lipid droplets as well as AD-1 and AD-2 positive cells were detected within the underlying muscle at 50 d. From 70 to 110 d of development, the AD-1 and AD-2 MAbs each detected all adipocytes examined, as well as capillaries associated with fat cell clusters in s.c. tissues. Reactivity toward both antibodies, as well as lipid deposition, also was detectable in the muscle underlying the s.c. mesenchyme from 70 d onward. Each MAb possessed a distinct pattern of reactivity. The AD-2 MAb stained arrector pili muscles and vessels in the s.c. mesenchyme and vessels in the underlying muscles, whereas the AD-1 did not. No reactivity using either MAb was detectable toward any other cell types within s.c. tissues. These results established the presence of cells expressing surface determinants found on mature adipocytes and associated capillaries prior to adipogenesis. A lineage relationship between adipocytes and capillary endothelial cells is suggested.     

Regulatory role of l-proline in fetal pig growth and intestinal epithelial cell proliferation

l-proline (Pro) is a precursor of ornithine, which is converted into polyamines via ornithine decarboxylase (ODC). Polyamines plays a key role in the proliferation of intestinal epithelial cells. The study investigated the effect of Pro on polyamine metabolism and cell proliferation on porcine enterocytes in vivo and in vitro. Twenty-four Huanjiang mini-pigs were randomly assigned into 1 of 3 groups and fed a basal diet that contained 0.77% alanine (Ala, iso-nitrogenous control), 1% Pro or 1% Pro + 0.0167% α-difluoromethylornithine (DFMO) from d 15 to 70 of gestation. The fetal body weight and number of fetuses per litter were determined, and the small and large intestines were obtained on d 70 ± 1.78 of gestation. The in vitro study was performed in intestinal porcine epithelial (IPEC-J2) cells cultured in Dulbecco''s modified Eagle medium-high glucose (DMEM-H) containing 0 μmol/L Pro, 400 μmol/L Pro, or 400 μmol/L Pro + 10 mmol/L DFMO for 4 d. The results showed that maternal dietary supplementation with 1% Pro increased fetal weight; the protein and DNA concentrations of the fetal small intestine; and mRNA levels for potassium voltage-gated channel, shaker-related subfamily, member 1 (Kv1.1) in the fetal small and large intestines (P < 0.05). Supplementing Pro to either gilts or IPEC-J2 cells increased ODC protein abundances and polyamine concentrations in the fetal intestines and IPEC-J2 cells (P < 0.05). In comparison with the Pro group, the combined administration of Pro and DFMO reduced the expression of ODC protein and spermine concentration in the fetal intestine, as well as the concentrations of putrescine, spermidine and spermine in IPEC-J2 cells (P < 0.05). Meanwhile, the percentage of cells in the S-phase and the mRNA levels of proto-oncogenes c-fos and c-myc were increased in response to Pro supplementation, whereas depletion of cellular polyamines with DFMO increased tumor protein p53 (p53) mRNA levels (P < 0.05). Taken together, dietary supplementation with Pro improved fetal pig growth and intestinal epithelial cell proliferation via enhancing polyamine synthesis.     

Effect of initial length of uterus per embryo on fetal survival and development in the pig

Influence of initial length of uterus available to each embryo on its subsequent survival and development was determined by systematic restriction of the length available to each potential embryo. Fifty-seven pregnant crossbred gilts were laparotomized at d 3 of gestation, length of uterine horns was measured in situ and corpora lutea (CL) were counted. In Exp. 1, uterine space available to each potential embryo was restricted by ligating one uterine horn 5 cm from the tip per CL. Uteri were examined at d 20, 25 or 50. In Exp. 2, one uterine horn was ligated on d 3 at 10, 20 or 30 cm from the tip per CL and uteri were examined at d 50. Embryos in the restricted section (RS) had a specific mean uterine length available to each potential embryo of 5, 10, 20 or 30 cm. Embryos in the nonrestricted section (NRS) had a variable mean uterine length available to each potential embryo of 44 +/- 4 cm. When embryos were restricted to 5 cm, the proportion of surviving fetuses at d 20, 25 and 50 was 61, 12 and 8%, respectively, whereas in combined NRS it was 82%. When the uterus was examined at d 50 after restricting embryos to 10, 20 or 30 cm/CL, 25, 33 and 52% of fetuses survived; in combined NRS survival was 71%. Each fetus surviving to d 50 in RS was associated with 36 cm of initial uterine length but fetal survival was not associated with number of CL. In RS, 59% were female fetuses and in NRS 50% were females.(ABSTRACT TRUNCATED AT 250 WORDS)     

B cell development in gut associated lymphoid tissues

B lymphocyte development can occur in a variety of anatomical sites. While typically considered to be a process that occurs in the bone marrow throughout life, it is becoming clear that gut associates sites of B cell development are critically important in many species of veterinary importance. Among these sites, the bursa of Fabricius in chickens and the ileal Peyer's patches of sheep are among the best studied. In these organs, it has become clear that many of the properties associated with B cell development in rodent and primate bone marrow do not apply. Thus while bone marrow B cell development typically involves an ongoing maturation of mature B cells from immature B lineage precursors that lack the expression of a surface immunoglobulin complex, gut associated lymphoid tissues (GALTs) may be colonized by a single wave of precursor cells during embryo development. Nonetheless, molecular analysis of the requirements for B lymphocyte development in GALTs reveals some striking parallels with requirements identified for B cell development in bone marrow. This article will discuss differences between B cell development in the bone marrow and GALTs and recent evidence emerging that yields insights into how these processes are regulated.     

Fructose utilization for nucleic acid synthesis in the fetal pig

Eight fetal pigs, in utero, were injected ip with 20 microCi/fetus [U14C]-fructose between d 55 and 65 pregnancy. The isotope was allowed to equilibrate between blood and tissues within injected fetuses for a period of 240 min. Fetal pigs were then sacrificed and nucleic acids were extracted from cold tissue homogenates of skeletal muscle and liver. Nuclide disintegrations per minute recovered in extracted DNA and RNA were used to calculate incorporation of labeled C from fructose. The recovery of labeled C per mmol of nucleic acids from skeletal muscle was greater (P less than .05) than that from liver. Relative incorporation of labeled C into skeletal muscle RNA (395.9 pmol/mmol) was greater (P less than .05) than for DNA (189.5 pmol/mmol). The same trend was observed for liver RNA (78.0 pmol/mmol) and DNA (55.6 pmol/mmol), but differences were nonsignificant. These data suggest that at least part of the high concentration of endogenous fructose measured in fetal pigs in utero is involved in synthesis of nucleic acids, thereby providing substrate for anabolic functions necessary for fetal growth and development.     

产前应激与胎儿发育

产前应激(prenatal stress,PS)是妊娠期母体受到各种内外界环境因素、社会和心理因素刺激时,所表现出的全身性、特异性适应反应。产前应激不仅影响母体本身,还可能影响胎儿的正常发育,甚至诱发终身疾病。发育中的胎儿对外界刺激具有较高的敏感性和较低的适应性,且产前应激对胎儿的生理和心理上都有较大的危害,致使后代生长发育迟缓、免疫功能紊乱、疾病易感性增加,而产前应激对胎儿的影响取决于应激的类型、时间、强度以及后代的性别,因此本研究主要综述光照应激、束缚应激、冷应激等几种产前应激对胎儿发育的影响,为研究动物产前应激提供理论基础。     

Cell surface immunoglobulin regulated checkpoints in chicken B cell development

The bursa of Fabricius is critical for the normal development of B lymphocytes in avian species. Productive colonization of bursal follicles by B cell precursors requires surface immunoglobulin expression. We have shown using retroviral gene transfer that expression of chimeric receptors containing the extracellular and transmembrane domains of murine CD8alpha and CD8beta fused to the cytoplasmic domains of chicken Igalpha and Igbeta can support productive bursal colonization in the chicken embryo in bursal cells lacking the expression of endogenous sIgM. We show here that chimeric receptor expression does not support continued bursal cell development after hatch. However intrabursal administration of anti-CD8 antibodies that ligate the CD8alpha:Igalpha chimeric receptor results in maintained numbers of bursal cells that express the chimeric receptor in the absence of endogenous sIgM. These results support a model in which sIgM receptor expression is required for productive bursal colonization in the chick embryo but sIgM receptor ligation is required to support later B cell development after hatch.     

Changes in fetal and maternal blood at the end of pregnancy and during parturition in the pig

Fetal and maternal blood gas tensions, pH, packed cell volume and glucose, fructose and lactic acid concentrations were monitored during the last two days of gestation, during parturition and and the first hour after birth. Blood samples were taken by means of indwelling catheters (implanted seven to 14 days before parturition) from 12 fetuses in seven sows. All fetuses were liveborn at a mean gestational age of 113.1 days. The significant finding was that all variables in fetal blood were stable during labour and, although mild hypercapnia was present during the last three hours, no significant changes in mean values were seen until those of samples taken within 15 minutes of birth. In some fetuses, no changes were seen until after birth, while in others pH and pO2 values declined during the last hour of fetal life. Immediately after birth a rapid increase in pO2 and decrease in pCO2 followed the onset of respiration. Blood pH fell during the first 30 minutes after birth and this fall was accompanied by increasing blood lactic acid concentrations. Blood glucose concentrations rose rapidly in the first 15 minutes after birth and were maintained during the first hour despite separation of the piglets from the sow. There was a transient, but significant, increase in packed cell volume during the period from 15 minutes before to 15 minutes after birth. Maternal values for all variables measured remained virtually unchanged during delivery.     

猪、牛生长发育的分形特性研究

通过观察猪、牛的生长发育过程 ,研究不同组织生长发育的不平衡现象 ,并首次对其分形表征的外显特性进行了讨论     

Avian B cell development: lessons from transgenic models

The bursa of Fabricius is critical for the development of B lymphocytes in avian species. Despite considerable advances in our understanding of the molecular mechanisms by which avian antibody diversity is generated, many stages of B-cell development in the bursa and the means by which they are regulated remain unclear. Here we discuss the use of productive chicken retroviral vectors which allow gene transfer in vitro or in vivo as tools to probe the requirements for bursal B-cell development. Expression of a truncated form of bursal cell surface IgM, lacking variable region encoded determinants, is sufficient to promote the initial colonization and clonal expansion of B-cells within the bursa. Expression of this truncated IgM does not, however, protect developing bursal cells against the apoptosis that occurs within the bursa after hatch. Conversely, over-expression of the proto-oncogene bcl-2, following retroviral gene transfer, protects cells against apoptotic cell death but is not sufficient to allow B lineage progression in the absence of sIgM expression. Finally we discuss the use of regulated promoters within the retroviral gene transfer system to show that while bursal cells are susceptible to transformation by the v-rel oncogene in vitro, this oncogene preferentially targets mature peripheral cells in vivo.