Effect of iscoms and their adjuvant moiety (matrix) on the initial proliferation and IL-2 responses: comparison of spleen cells from mice inoculated with iscoms and/or matrix

In the iscom, antigen is attached by hydrophobic interactions to a matrix which is built up by the adjuvant Quil A and lipids. Thus, the iscom presents antigen in multiple copies on a small particle with a built-in adjuvant. By studying the specific antibody response, in vitro proliferation and IL-2 secretion by splenocytes from mice following different in vivo treatments with iscoms and/or matrix, we attempted to distinguish between nonspecific stimulatory effects, caused by the matrix or iscoms, and specific responses to the antigens incorporated into iscoms. The results strongly suggest that matrix and also iscoms exert a nonspecific adjuvant activity by a transient high spontaneous proliferation of cells collected within 2 weeks after administration of iscoms or matrix. This high rate of proliferation was preceded by suppressed proliferation, 3 days after injection with matrix or iscom. The adjuvant component included in iscoms, i.e., the matrix, does not excert a mitogenic stimulation in vitro or influence the levels of specific antibodies in serum. Specific responses to the antigens included in iscoms were recorded both as increasing levels of serum antibodies and as iscom-induced proliferation of immune spleen cells in vitro. The recruitment of IL-2 was only related to the specific stimulation induced by the antigens in iscom.     

Transport of steroids between fetuses via amniotic fluid in relation to the intrauterine position phenomenon in rats.

In litter-bearing mammals, the course of development of male and female fetuses is affected by the presence of other fetuses of the same or opposite sex located nearby within the uterus. The transport of testosterone between rat fetuses was examined by implanting a Silastic capsule containing [3H]testosterone into the amniotic sac of a fetus at either the ovarian or cervical end of a uterine horn on days 19 and 20 of pregnancy. The amount of testosterone that was recovered from the amniotic fluid of other fetuses 12 h later was determined. The amniotic fluid surrounding the adjacent fetus on the cervical side of the implanted fetus contained three times as much [3H]testosterone as did the adjacent fetus on the ovarian side, regardless of where in the uterus the implant was made. The movement of dye injected into the uterine lumen was towards the cervix. Intraluminal fluid movement may thus mediate the greater transport of [3H]testosterone towards the cervix than towards the ovary. Our findings support the hypothesis that transport of testosterone between fetuses occurs across the fetal membranes via diffusion, such that any fetus (male or female) located between male fetuses receives the greatest supplement of testosterone.     

Escherichia coli mutant lacking 4-thiouridine in its transfer ribonucleic acid.

A mutant of Escherichia coli has been isolated that lacks 4-thiouridine, a rare base in transfer ribonucleic acid. The mutant grows at the same rate as wild-type cells. It shows little near-ultraviolet-induced growth delay, thus supporting earlier hypotheses that 4-thiouridine in transfer ribonucleic acid is the chromophore for this growth delay.     

Inactivation of adenosine 5''-triphosphate synthesis and reduced-form nicotinamide adenine dinucleotide dehydrogenase activity in Escherichia coli by near-ultraviolet and violet radiations.

Near-ultraviolet (near-UV) light (300 to 380 nm) is a significant component of sunlight and has a variety of effects on biological systems. The present work is an attempt to identify chromophores (molecular absorbers of light) and targets (critical damaged molecules) for inhibition of adenosine triphosphate (ATP) synthesis in Escherichia coli by near UV. The fluence of 334 nm required for 37% survival of net ATP synthesis (F37) in E. coli AB2463 in succinate medium is 140 kJ/m2. The action spectrum for this inactivation is almost structureless, exhibiting a smooth transition from high efficiency at 313 nm to low efficiency at 405 nm. The action spectrum for inhibition of net ATP synthesis is consistent with the chromophore being either ubiquinone Q-8 or vitamin K2. The fluence required is consistent with ubiquinone Q-8 also being a target molecule. The activity of reduced nicotinamide adenine dinucleotide dehydrogenase in extracts of E. coli B is also inactivated by near UV and shows an F37 of about 40 kJ/m2. The action spectrum for this effect is quite structureless; it shows high efficiency at 313 nm and low efficiency at 435 nm. The data do not suggest a target molecule for this action, although it is possible that ubiquinone Q-8 absorbs the near-UV energy and then passes it on to some other target molecule. The data further indicate that inactivation of the oxidative phosphorylation system is not a primary factor in near-UV-induced growth delay in E. coli.     

Utilization of D-asparagine by Saccharomyces cerevisiae.

Yeast strains sigma1278b and Harden and Young, which synthesize only an internal constitutive form of L-asparaginase, do not grow on D-asparagine, as a sole source of nitrogen, and whole cell suspensions of these strains do not hydrolyze D-asparagine. Strains X2180-A2 and D273-10B, which possess an externally active form of asparaginase, are able to grow slowly on D-asparagine, and nitrogen-starved suspensions of these strains exhibit high activity toward the D-isomer. Nitrogen starvation of strain X218O-A2 results in coordinate increase of D- and L-asparaginase activity; the specific activity observed for the D-isomer is approximately 20% greater than that observed for the L-isomer. It was observed, in studies with cell extracts, that hydrolysis of D-asparagine occurred only with extracts from nitrogen-starved cells of strains that synthesize the external form of asparaginase. Furthermore, the activity of the extracts toward the D-isomer was always higher than that observed with the L-isomer. A 400-fold purified preparation of external asparaginase from Saccharomyces cerevisiae X218U-A2 hydrolyzed D-asparagine with an apparent Km of 0.23 mM and a Vmax of 38.7 mumol/min per mg of protein. D-Asparagine was a competitive inhibitor of L-asparagine hydrolysis and the Ki determined for this inhibition was approximately equal to its Km. These data suggest that D-asparagine is a good substrate for the external yeast asparaginase but is a poor substrate for the internal enzyme.     

Confirmation of QTL on porcine chromosomes 1 and 8 influencing leukocyte numbers, haematological parameters and leukocyte function

A genome wide search in European Wild Boar x Swedish Yorkshire (W x Y) inter-cross pigs has earlier identified quantitative trait loci (QTL) for leucocyte number and function on porcine chromosomes 1 and 8 (SSC 1 and 8). To verify the involvement of these chromosomal regions in the regulation of haematocrit (Hem) and haemoglobin (Hb) levels, leucocyte numbers and in vitro leukocyte functions (mitogen induced proliferation and IL-2 production, virus induced interferon-alpha production and neutrophil phagocytosis), animals of different genetic backgrounds were analysed. The animals comprised a back-cross sire family (n=47) of W x Y pigs and six crossbred [Y x Landrace (L)] sire families (n=191). They were genotyped for 16 genetic markers and an interval analysis was performed. On SSC1, a QTL close to S0082 on the q-arm that influenced numbers of white blood cells in L x Y pigs and numbers of band neutrophils and CD8(+) cells in W x Y pigs was identified (P相似文献   

Lactate dehydrogenase-elevating virus replication persists in liver, spleen, lymph node, and testis tissues and results in accumulation of viral RNA in germinal centers, concomitant with polyclonal activation of B cells.

Lactate dehydrogenase-elevating virus (LDV) replicates primarily and most likely solely in a subpopulation of macrophages in extraneuronal tissues. Infection of mice, regardless of age, with LDV leads to the rapid cytocidal replication of the virus in these cells, resulting in the release of large amounts of LDV into the circulation. The infection then progresses into life-long, asymptomatic, low-level viremic persistence, which is maintained by LDV replication in newly generated LDV-permissive cells which escapes all antiviral immune responses. In situ hybridization studies of tissue sections of adult FVB mice revealed that by 1 day postinfection (p.i.), LDV-infected cells were present in practically all tissues but were present in the highest numbers in the lymph nodes, spleen, and skin. In the central nervous system, LDV-infected cells were restricted to the leptomeninges. Most of the infected cells had disappeared at 3 days p.i., consistent with the cytocidal nature of the LDV infection, except for small numbers in lymph node, spleen, liver, and testis tissues. These tissues harbored infected cells until at least 90 days p.i. The results suggest that the generation of LDV-permissive cells during the persistent phase is restricted to these tissues. The continued presence of LDV-infected cells in testis tissue suggests the possibility of LDV release in semen and sexual transmission. Most striking was the accumulation of large amounts of LDV RNA in newly generated germinal centers of lymph nodes and the spleen. The LDV RNA was not associated with infected cells but was probably associated with virions or debris of infected, lysed cells. The appearance of LDV RNA in germinal centers in these mice coincided in time with the polyclonal activation of B cells, which leads to the accumulation of polyclonal immunoglobulin G2a and low-molecular-weight immune complexes in the circulation.     

Factors Affecting the Incidence of Necrotic Enteritis,Caecal Carriage of Clostridium perfringens and Bird Performance in Broiler Chicks

Two trials were conducted to study the effects of a competitive exclusion (CE) product BROILACT® and the anticoccidial narasin on the incidence of necrotic enteritis (NE), the numbers of Clostridium perfringens (CP) in the caeca of broiler chicks and the performance of the birds. In trial 1 the effects of type of protein and partial replacement of a narasin containing diet with whole wheat were also studied. All groups of chicks were studied up to the point of slaughter at 43 days of age and after evisceration in a processing plant to determine slaughter yield. In trial 1, statistically significant results included the following: CE-treatment reduced total mortality, and incidence of NE, on diet containing animal but not vegetable protein. Caecal carriage of CP was also reduced, while slaughter yield increased. Narasin reduced caecal carriage of CP and increased both growth rate and slaughter yield in both trials. Whole wheat replacement improved feed conversion but reduced bird growth rate. In trial 2, both CE-treatment and narasin influenced feed intake, CE-treatment significantly only at days 22 and 44. Narasin improved feed conversion until 5 weeks of age and CE-treatment did so until 22 days of age. In both trials, there was also an interaction effect indicating that CE-treatment increased slaughter yield for birds that were not fed narasin.