The ultrastructure of neonatal calf intestine and absorption of heterologous proteins

Difructose Anhydride and Passive Immunity Effects on Passive Immune Transfer and Performance of Feeding Difructose Anhydride to Neonatal Calves

The objective of this study was to assess the potential effects of supplementing difructose anyhdride III (DFAIII) during the first days of life on the absorption of immunoglobulin G (IgG) and growth performance of calves early in life fed colostrum with a high IgG concentration. Sixty-six healthy new-born Holstein calves were randomly assigned to three treatments consisting of no supplementation (control), supplementation of 12 g/d (DFA12), or 36 g/d (DFA36) of DFAIII during the first 7 d of life via colostrum and milk replacer (MR). Calves were separated from dams at birth and bottle-fed colostrum in two meals, each targeting 2.5 L within the first 18 h of birth. Colostrum had been previously collected from other dams (and preserved frozen) within the first 2 h of calving and had a Brix value ≥32%. Daily consumption of starter concentrate and MR (and colostrum on the first day) were individually monitored. Calves were body weighed using an electronic scale at birth and on a weekly basis thereafter until the end of study at 42 d of age. A sample of colostrum fed to each calf and a blood sample from the jugular vein of the calves were collected at 12 and 24 h of life to determine the IgG concentration. The mean colostrum IgG concentration fed in the current study was 110 ± 33.7 g/L (mean ± SD). No differences in animal performance were found among the treatments. Calves on all treatments consumed the same amount of colostrum with a similar concentration of IgG, and thus the amount of IgG consumed was also similar. Serum IgG concentrations were greater at 24 than at 12 h but did not differ among treatments. However, the apparent efficiency of absorption of colostral immunoglobulins was greater in DFA12 and DFA36 at 12 h of life than in control calves, with no differences observed at 24 h. Even when feeding high-quality colostrum, in terms of IgG concentration, supplementation with difructose anhydride III may pose an additional advantage in promoting the passive transfer of immunoglobulins in neonatal Holstein calves during the first 12 h of life.

Feeding colostrum and transition milk facilitates digestive tract functionality recovery from feed restriction and fasting of dairy calves

The objective of this study was to evaluate the digestive tract recovery and metabolism of feeding either bovine colostrum (BC), transition milk (TM), or milk replacer (MR) after an episode of feed restriction and fasting (FRF) in dairy calves. Thirty-five Holstein male calves (22 ± 4.8 d old) were involved in a 50-d study. After 3 d of feeding 2 L of rehydration solution twice daily and 19 h of fasting (d 1 of study), calves were randomly assigned to one of the 5 feeding treatments (n = 7): calves were offered either pooled BC during 4 (C4) or 10 (C10) days, pooled TM during 4 (TM4) or 10 (TM10) days, or MR for 10 d (CTRL) at the rate of 720 g/d DM content. Then, all calves were fed the same feeding program, gradually decreasing MR from 3 L twice daily to 2 L once daily at 12.5% DM until weaning (d 42), and concentrate feed, water, and straw were offered ad libitum until d 50. Citrulline, Cr-EDTA, β-hydroxybutyrate (BHB), and nonesterified fatty acids (NEFA) in serum and complete blood count (CBC) were determined on d -3, 1, 2, 5, and 11 relative to FRF, except BHB and NEFA at d -3. Volatile fatty acids (VFA), lactoferrin (LTF), IgA, and microbiota (Firmicutes to Bacteroidetes ratio and Fecalis prausnitzii) were analyzed in feces on d 5 and 11 before the morning feeding. Health scores were recorded daily from d -3 to d 14 as well as d 23 and 30. Feed concentrate, MR, and straw intake were recorded daily, and body weight on d -3, 1, 2, 5, and 11 and weekly afterward. Calf performance, intake, serum Cr-EDTA, CBC, fecal LTF concentrations and microbiota parameters were similar among treatments throughout the study. Serum NEFA concentrations were greater in TM4, TM10 and C10 calves compared with the CTRL ones from d 2 to 11, and after the FRF, serum concentrations of BHB were lower in CTRL calves than in the other treatments, and on d 11, serum BHB concentrations in the long treatments (C10 and TM10) remained greater than those in the shorter ones (C4 and TM4) and CTRL. Serum citrulline concentrations were similar on d -3 and 1 in all treatments, but they were greater in C4, C10, TM4, and TM10 on d 2 and 5, and on d 11 they were only greater in C10 and TM10 than in CTRL calves. Fecal IgA concentrations tended to be greater in C10 than in CTRL, TM4, and TM10 calves, and in C4 and TM10 than in CTRL animals. Fecal propionate proportion was lesser in C10 than in CTRL, TM4, and TM10 calves, while butyrate was greater in C4 and C10 than in TM4 and CTRL calves. The proportion of non-normal fecal scores of C10 fed calves was greater than TM4 and TM10 calves. Results showed that TM and BC may help to recover intestinal functionality, provide gut immune protection, and increase liver fatty acid oxidation in calves after a FRF episode.

Invited review: The importance of colostrum in the newborn dairy calf

It is critical that bovine maternal colostrum is fed to newborn calves during their first hours of life. Colostrum is the secretion a cow produces after mammary involution that is rich in various nutrients. In addition to the nutritive value for newborn calves, immunoglobulins are of interest due to their role in developing the naïve immune system of calves at birth. The process by which a calf acquires immunity via absorption of immunoglobulins is defined as passive immunity. When calves consume an adequate amount of immunoglobulins, they are classified as having successful passive immunity (SPI). In contrast, if they are deprived of adequate colostrum, they are considered to have had a failure of transfer of passive immunity (FPI). Transfer of passive immunity is assessed by measuring serum IgG concentrations at 24 to 48 h of age. The major factors that influence whether a calf has SPI or FPI are colostrum IgG concentration, quantity fed, and age of calf at colostrum feeding. Monitoring apparent efficiency of immunoglobulin absorption in calves is often recommended to evaluate overall colostrum management practices. Serum IgG analyses can be determined with direct (radial immunodiffusion) or indirect (refractometry) methods and used to assess SPI or FPI prevalence.

Colostrum Management for Dairy Calves

Colostrum management is the single most important management factor in determining calf health and survival. Additional benefits of good colostrum management include improved rate of gain and future productivity. Successful colostrum management requires producers to provide calves with a sufficient volume of clean, high-quality colostrum within the first few hours of life. This article reviews the process of colostrogenesis and colostrum composition, and discusses key components in developing a successful colostrum management program. In addition, the article discusses approaches for monitoring and proposes new goals for passive immunity in dairy herds.

Effect of butyrate on passive transfer of immunity in dairy calves

The objectives of this study were to determine the effects of supplemental butyrate on (1) Ig production in dams and (2) Ig absorption in their calves. Twenty dry dams fed a close-up total mixed ration were assigned to either a control treatment (CTRL-D) or a butyrate treatment where the close-up total mixed ration was supplemented with butyrate at 1% of dry matter intake (wt/wt; BUT-D). At calving, calves were assigned to 1 of 2 treatments: a control group fed colostrum replacer only (CTRL-C) and a butyrate group fed colostrum replacer with supplemental butyrate at 2.5% (wt/vol; BUT-C). Serum IgG, glucose, and β-hydroxybutyrate were measured weekly in both dams and calves. Additionally, calves were weighed weekly to determine average daily gain. In dams, serum IgG concentration was not different between CTRL-D and BUT-D (1,785 ± 117 vs. 1,736 ± 137 mg/dL, respectively), nor was there a change in Ig levels in the colostrum between control and butyrate groups. Serum total protein did not differ between CTRL-D and BUT-D dams. Dam dry matter intake did not differ between CTRL-D and BUT-D but did decrease 1 wk before parturition. Compared with CTRL-C calves, BUT-C calves had significantly decreased serum IgG concentration at 24 h (2,110 ± 124 vs. 1,400 ± 115 mg/dL), wk 1 (1,397 ± 121 vs. 866 ± 115 mg/dL), and wk 2 (1,310 ± 121 vs. 797 ± 115 mg/dL). Additionally, apparent efficiency of absorption was lower for the BUT-C group compared with the CTRL-C group (35.3 ± 2.1 vs. 25.9 ± 2.0). Differences in serum Ig concentrations between the CTRL-C and BUT-C groups did not affect average daily gain (0.59 ± 0.05 vs. 0.48 ± 0.05 kg/d, respectively), serum glucose concentrations, or serum β-hydroxybutyrate concentrations. These data demonstrate that butyrate inclusion in colostrum negatively affects IgG absorption in newborn calves, whereas calf body weight gains were unaffected.

Effects of feeding pregnant beef cows selenium-enriched alfalfa hay on passive transfer of ovalbumin in their newborn calves

Intestinal absorption of immunoglobulins is critical for health and survival of newborn calves because there is no transfer of immunoglobulins in utero. The objective of this study was to determine if feeding beef cows Se-enriched alfalfa hay during the last trimester of gestation improves passive transfer of ovalbumin (OVA), a surrogate protein marker for IgG absorption. Control cows (n = 15) were fed non-Se-fortified alfalfa hay (5.3 mg Se/head daily) plus a mineral supplement containing inorganic Se (3 mg Se/head daily). Med-Se (n = 15) and High-Se cows (n = 15) were fed Se-biofortified alfalfa hay (27.6 and 57.5 mg Se/head daily, respectively); both groups received mineral supplement without added Se. Calves were randomly assigned to receive orally administered OVA at 12, 24, or 36 h of age. Calves that received their oral dose of OVA at 12 h of age had higher serum OVA concentrations across the first 48 h of life if born to High-Se cows compared to calves born to Control cows (P = 0.05), with intermediate values for calves born to Med-Se cows. Our results, using OVA as a model for passive transfer, suggest that if calves do not receive adequate colostrum to reach maximum pinocytosis, then supranutritional Se supplementation in beef cattle may improve passive transfer in their calves, if calves receive colostrum within the first 12 h of age.

Effect of delaying colostrum feeding on passive transfer and intestinal bacterial colonization in neonatal male Holstein calves

The objective of this study was to investigate the effect of time of first colostrum feeding on the passive transfer of IgG and on bacterial colonization in the intestine of neonatal dairy calves. Twenty-seven male Holstein calves were randomly assigned to 1 of 3 treatments at birth: calves were fed colostrum at 45 min (0 h, n = 9), 6 h (n = 9), or 12 h after birth (n = 9). Calves were fed pooled, heat-treated colostrum (62 g of IgG/L) at their respective feeding times at 7.5% of birth body weight and fed milk replacer at 2.5% of birth body weight per meal every 6 h thereafter. Blood samples were taken every 3 h using a jugular catheter and were analyzed for determination of serum IgG by radial immunodiffusion. At 51 h after birth, calves were euthanized for collection of tissue and digesta of the distal jejunum, ileum, and colon. Quantitative real-time PCR was used to estimate the prevalence of Bifidobacterium spp., Lactobacillus spp., Fecalibacterium prausnitzii, Clostridium cluster XIVa, and total Escherichia coli. Delaying colostrum feeding by 6 h (35.6 ± 1.88%) and 12 h (35.1 ± 3.15%) decreased the maximum apparent efficiency of absorption of IgG compared with feeding colostrum immediately after birth (51.8 ± 4.18%) and delayed the time to maximum serum IgG concentration (24 h vs. 15 h, respectively). Moreover, 12-h calves tended to have a lower prevalence of Bifidobacterium spp. (0.12 ± 0.017%) and Lactobacillus spp. (0.07 ± 0.019%) associated with the colon mucosa compared with 0-h calves (1.24 ± 0.648% and 0.26 ± 0.075%, respectively). In addition, 6-h (0.26 ± 0.124%) and 12-h (0.49 ± 0.233%) calves had a lower prevalence of total E. coli associated with ileum mucosa compared with 0-h calves (1.20 ± 0.458%). These findings suggest that delaying colostrum feeding within 12 h of life decreases the passive transfer of IgG and may delay the colonization of bacteria in the intestine, possibly leaving the calf vulnerable to infections during the preweaning period.

Colostral transfer of gamma glutamyl transpeptidase in calves

Serum gamma glutamyl transpeptidase (GGT) levels in blood samples taken from normal calves which bad suckled colostrum were much higher than those found in healthy adult cattle. Levels of over 60 times the normal adult level were observed. These high levels of GGT took approximately 5 weeks to decline to adult values. Calves which appeared to have not received or absorbed colostrum had GGT levels which would be considered normal in adult cattle. A calf with serum gamma globulin levels which indicated an intermediate amount of colostrum absorption had a level of GGT which was intermediate between that expected for normal adult cattle and that found in calves which had more fully absorbed colostrum. The mean GGT level observed in colostrum from 6 newly-calved cows was over 800 times the mean serum GGT level of the same 6 cows. It therefore appears most likely that GGT is concurrently absorbed with colostrum by calves and this gives rise to the very high levels seen in normal calves. Calves with very high levels of serum GGT also had raised levels of alkaline phosphatase (AP) which slowly declined but never reached normal adult levels within the 53-day period of observation. It therefore appears that high levels of both GGT and AP are achieved by calves at the time of colostrum absorption and it is concluded that clinical interpretation of serum GGT and AP levels in young calves is closely dependent upon parallel knowledge of their serum gamma globulin levels.

Colostrum management for dairy calves

Colostrum management is the single most important management factor in determining calf health and survival. Unfortunately, a significant proportion of North American dairy calves suffer from failure of passive transfer of antibodies from colostrum, contributing to excessively high preweaning mortality rates and other short- and long-term losses associated with animal health, welfare, and productivity. A successful colostrum management program requires producers to consistently provide calves with a sufficient volume of clean, high-quality colostrum within the first few hours of life. This article reviews the process of colostrogenesis and discusses important components of colostrum. The key components of delivering and monitoring a successful colostrum management program are discussed.

Endocytosis of cholera toxin by human enterocytes is developmentally regulated

Many secretory diarrheas including cholera are more prevalent and fulminant in young infants than in older children and adults. Cholera toxin (CT) elicits a cAMP-dependent chloride secretory response in intestinal epithelia, which accounts for the fundamental pathogenesis of this toxigenic diarrhea. We have previously reported that the action of this bacterial enterotoxin is excessive in immature enterocytes and under developmental regulation. In this study, we tested the hypothesis that enhanced endocytosis by immature human enterocytes may, in part, account for the excessive secretory response to CT noted in the immature intestine and that enterocyte endocytosis of CT is developmentally regulated. To test this hypothesis, we used specific inhibitors to define endocytic pathways in mature and immature cell lines. We showed that internalization of CT in adult enterocytes is less and occurs via the caveolae/raft-mediated pathway in contrast to an enhanced immature human enterocyte CT uptake that occurs via a clathrin pathway. We also present evidence that this clathrin pathway is developmentally regulated as demonstrated by its response to corticosteroids, a known maturation factor that causes a decreased CT endocytosis by this pathway.

Do cows fed BSE-infected meat and bone meal in the colostrum-producing stage pass on infectious BSE agent to their calves?

Direct ingestion of the infectious BSE agent via meat and bone meal (MBM) is commonly regarded as the main route of infection for cattle. I propose that another plausible route of infection has been overlooked so far, namely the ingestion of MBM by mother animals who susequently pass on the infectious agent in their colostrum and thus infect their offspring. This theory could explain why, although infection is thought to occur at very early stages in life, many BSE animals had not received MBM containing feeds when calves. Literature evidence on intact protein absorption in adult mammals, on the presence of the infectious BSE agent in the blood in the pre-symptomatic stage, and on the incorporation of intact dietary protein into colostrum or milk in humans and pigs, support this hypothesis. This hypothesis does not necessarily mean that colostrum or milk from BSE-positive animals is infectious. Rather, the mother animals in the hypothesis scenario will be themselves infected, but probably not develop the disease due to its long incubation period, thus occurring in statistics as 'negative' animals.

Oral administration of IL-1 beta enhanced the proliferation of lymphocytes and the O(2)(-) production of neutrophil in newborn calf

Recently, we demonstrated the presence of IL-1 beta in the colostral whey from dairy cows. Here, authors examined oral transmission of colostral IL-1 beta and its immunological effects on the neonatal calves. Biotin-labeled recombinant bovine (rb) IL-1 beta was administered orally to newborn calves and monitored in the serum. The results disclosed the passive transfer of colostral cytokines via the oral route, and a potent increase in white blood cell (WBC) count was observed in all calves administered with rbIL-1 beta. Oral administration of IL-1 beta significantly increased the proliferation of peripheral blood mononuclear cells (PBMCs) stimulated with concanavalin A, and the O(2)(-) production of stimulates neutrophils in newborn calves. These results suggest that the oral administration of IL-1 beta has an immunostimulatory activity in the newborn calf.

Apical tubules in marginal cells of the differentiating stria vascularis

BACKGROUND

Apical tubules (ATs) in marginal cells (MCs) of the stria vascularis appear in limited stages of differentiation of the MCs, but their origin and roles remain uncertain. The present study was designed to solve the problem of whether the ATs are intracellular compartments derived from the Golgi apparatus (GA).

METHODS

The cochleae of Wistar rats at ages of postnatal days 1, 3, and 5 were prepared for electron microscopy and cytochemistry using thiamine pyrophosphatase (TPPase) and coenzyme A phosphatase (CoA-Pase) as marker enzymes of trans Golgi cisterns and fluorescent labelled lectin, griffonia simplicifolia agglutinin-I (GS-1).

RESULTS

The ATs appeared in the apical cytoplasm of the MCs between postnatal days 1 and 5. Reaction products of TPPase and CoA-Pase activities were localized in the trans-Golgi cisterns and the ATs, which were occasionally in a close apposition to the GA. The reaction was found along the apical plasma membrane of the MCs only in case of TPPase. Heavy reactions to GS-1 were seen in the supranuclear region as well as along the apical plasma membrane of the MCs.

CONCLUSIONS

The present ultrastructural and cytochemical studies indicate that the ATs, which appear in the MCs at limited perinatal stages, originate from the trans-Golgi cisterns. These ATs may be involved in the apical plasma membrane supply for the differentiation of the MCs prior to the generation of EP.

Ultrastructure of pre- and postcolostral enterocytes of the newborn calf

Ten calves were used to elucidate the ultrastructure of enterocytes before and 24 h after colostral intake. Tissue samples were obtained from duodenum, jejunum (5 locations) and ileum. Protein A-gold technique was applied to immunoelectron-microscopically demonstrate colostral IgA. The prominent feature of the precolostral enterocytes are intracytoplasmic vacuoles. The frequency of vacuoles increases from cranial jejunum to ileum and from the villi bases to the tips. The appearance of absorptive vacuoles after colostral administration correlates with the incidence of precolostral empty vacuoles. Bovine IgA was detected in absorptive vacuoles and within the intestinal lumen of postcolostral calves. In addition to a diffuse IgA labelling of most vacuoles, a few corresponding enterocytic vacuoles labelled inhomogenously or negatively. This study demonstrates morphologically that the main site of colostral absorption is the middle-to-caudal region of the small intestine. Immunoelectron microscopy of IgA labelling provides indications of a selective IgA absorption in addition to pinocytosis.

Ultrastructure of fetal alimentary organs: stomach and spiral intestine in the southern stingray, Dasyatis americana

In the fetal southern stingray, Dasyatis americana, both the stomach and spiral intestine function early in development to digest and absorb nutrient histotroph elaborated by uterine villi termed trophonemata. The gastric mucosa consists of a surface columnar mucous epithelium that is confluent with gastric pits or foveolae. Gastric glands are populated by oxynticopeptic and enteroendocrine cells. The surface mucous cells are pyramidal with apical microvilli. Oxynticopeptic cells are low columnar with a distinct and elaborate tubulovesicular system in the apical cytoplasm. Microvilli line the lumen of the gastric glands and cells have elaborate interdigitating lateral folds. Enteroendocrine cells are characterized by basal granules and a prominent rough endoplasmic reticulum. The fetal intestine is filled with bile-tinged viscous fluid. A core of submucosa supports spiral intestinal plicae that form the spiral valve from which villi project. The most prominent characteristic of the cells are enormous supranuclear vesicles formed by coalescence of smaller endocytotic vesicles. The apical cytoplasm has a profusion of smooth tubules, endoplasmic reticulum, and lysosomes. The large vesicles are interpreted as storage depots for continually ingested histotroph. Small vesicles may then bud off to be digested via the lysosomal system.

Immunoelectron microscopical demonstration of the absorption of colostral IgG by small intestinal enterocytes in newborn rats

The protein A-gold technique was used in the cranial, transitional and caudal segments of the small intestine of 12 newborn rats to demonstrate the process of absorption of gold-labelled IgG through the enterocytes. The observation of the attachment of labelled IgG molecules to the wall of coated vesicles suggested a receptor-mediated transport of colostral IgG in the cranial segment of the small intestine. However, intracellular micropinocytotic transport predominated in the transitional and caudal segments of the small intestine. There was no evidence for paracellular transport. Lysosomal structures in the enterocytes did not appear to impede the absorptive activity during the absorption period, which lasted 20 days.

An immunoelectron microscopic investigation of colostral IgG absorption across the intestine of newborn calves

The protein A-gold was used to examine the transport of colostral IgG from the lumen of the gut to the circulation in four newborn calves and one 24-hour-old calf. The absorptive enterocytes of the duodenum, jejunum and ileum were investigated five to 60 minutes after administering colostrum, and 24 hours after birth. In the newborn calves, an intracellular micropinocytotic transport of IgG molecules was dominant throughout the entire small intestine. The amount transported increased from the duodenum to the ileum. In addition, evidence of a selective, receptor-mediated transport of IgG during the first few hours of life was provided by the presence of bovine clathrin at the microvillous membrane of the duodenal and jejunal enterocytes, indicating the existence of specialised vesicles for transport, the so-called 'coated' vesicles. No sign of paracellular transport was detected. Intestinal closure was interpreted as a multifactorial event comprising the replacement of the fetal intestinal epithelial cells by more mature populations, the initial cessation of transport at the basal and lateral cell membrane of the absorptive enterocytes, and an increase in intracellular proteolytic activity by lysosomes.

[Lysosomal structures in the intestinal epithelium of mammals during their pre- and postnatal development. A micromorphometric-functional synopsis]

The first lysosomes appear in the stratified embryonic intestinal epithelium during its transition into the simple columnar form. This occurs concurrently with the initial villogenesis. Lysosomes situated basally in the epithelium are presumably the precursor of the first giant lysosomes in the lower small intestine of rodents. Immediately after establishment of the simple configuration a special form of secondary lysosomes can be observed, i.e. glycogenosomes, in the ephemerally existing huge glycogen containing areas. During subsequent fetal intestinal development one observes two events in the epithelial cells, which are the same in principle but differ in one essential point, while they exhibit partially impressive structures. On the one hand there are autophagic degenerative lysosomal processes in the villous epithelium until birth, that lead to a surface without villi in the large intestine, where they occur particularly frequently. On the other hand giant lysosomes originate perinatally in the lower small intestine as well as in the caecum and colon ascendens, in which protein molecules, which were transported by a system of inframicrovillar membranes, are lysosomally degraded, which can be defined as a heterophagic event.

Prenatal and postnatal development of the large intestine in the insectivore Suncus murinus, the laboratory shrew

Development of the large intestine in the insectivore Suncus murinus (the laboratory shrew) was investigated from day 21 to 30 of gestation and from birth to 20 days of age. Two days before birth, the stratified epithelium in the large intestine changed into a single layer. Although neither villi nor villus-like structures were ever present, fissures, corresponding to openings of the crypts, appeared on the mucosal surface before birth. These increased in number as well as in width and depth, connected with each other, and gave the mucosal surface a ridge-like appearance by 20 days of age. An elevation containing submucosae appeared shortly after birth and formed a large circular fold during the neonatal period. Goblet cells were the predominant epithelial cell type. Individual epithelial cells were mature-looking a few days before birth; goblet cells contained numerous mucous globules and absorptive cells possessed well-developed organelles. However, although goblet cells increased in number and exhibited active mucous-releasing forms after birth, absorptive cells never showed morphologic evidence of active endocytosis, such as apical endocytotic complexes and large supranuclear vacuoles. Each epithelial cell was similar in ultrastructure to that of the adult shortly after birth.

Milk intake before first colostrum in newborn dairy calves. Effect on intestinal transmission of macromolecules

The aim of this experiment was to investigate if ingestion of non-colostrum milk before first colostrum by calves impaired intestinal transmission of macromolecules from colostrum fed to calves 8, 16, and 24 h later. This design reflects the situation when calves are born in housing systems where the cow and her newborn calf are not separated from the herd, which gives the calf opportunity to suckle cows other than the mother. Two groups of eight calves each were fed pooled colostrum three times at 8, 16, and 24 h of age. One of the groups were fed non-colostrum milk 30 min after birth. Marker molecules were used to estimate absorption from each colostrum feeding. Blood samples were taken 8 h after each feeding and at 1 wk of age. At no time was there any significant difference between the plasma IgG means of the two groups. There was no difference in transmission of the marker molecules. It was concluded that early ingestion of non-colostrum milk before first colostrum does not change intestinal permeability to colostral macromolecules.

Variation in serum concentrations of immunoglobulins G, A, and M in Canadian Holstein-Friesian calves

Radial immunodiffusion was used to quantify Ig concentrations (mg/100 ml) in the sera of 74 male and 82 female Holstein calves and in whole colostrum from their dams. Calves were the progeny of 15 AI bulls. Blood samples were collected by jugular puncture from calves at birth, 24 to 36 h post first colostrum ingestion, and then weekly from 3 to 7 wk of age. Colostrum was sampled within 6 h of parturition. Mean calf serum Ig profiles showed peak concentrations of all isotypes by d 1 of age, which declined greatly by 3 to 4 wk, followed by gradual increases to 7 wk. Within isotype, there were highly significant positive correlations between serum concentrations in calves from 3 to 7 wk and between colostral and calf serum concentrations up to 5 wk, depending on isotype. Effects of season and location on calf serum isotype concentrations were important, but effects of ease of calving and twinning were small. Paternal half-sib heritability estimates computed by restricted maximum likelihood ranged from 0 to .20 for IgG, 0 to .45 for IgA, and 0 to .26 for IgM, depending on sampling period, and were .07, .08, and 0 for IgG, IgA, and IgM, averaged over all sampling periods. Although standard errors were large, heritability estimates for passive (24 to 36 h) and onset of active (3 to 4 wk) immunity suggested a moderately important additive genetic component and that these serum Ig concentrations could possibly be manipulated to produce more disease-resistant dairy calves.

Prenatal and postnatal development of the small intestine in the insectivore Suncus murinus

The development of the small intestine in the insectivore Suncus murinus was noted during the period from 21 days' gestation to 20 days after birth. At 21 days of gestation, the proximal small intestine exhibited the beginning of villus formation, whereas the distal small intestine preserved the stratified epithelium. Stratified epithelium in the distal small intestine changed into a single layer by 24 days' gestation. At 26 days' gestation, each epithelial cell was immature; but by 28 days mature-looking epithelial cells were found. The shape of the villi changed from cuboid to columnar during the same period. The connective-tissue cores of the villi began to develop at 7 days after birth in the proximal small intestine and at 15 days after birth in the distal small intestine. Crypts appeared at 15 days after birth. Endocytosis of epithelial cells took place at 28 days of gestation. In the proximal small intestine, supranuclear vesicle clusters were observed first at birth; they began to decrease both in number and size at 10 days' gestation and then disappeared completely by 20 days after birth. In the distal small intestine, large supranuclear vacuoles were observed first at 28 days of gestation. Although these vacuoles invariably were found up to 15 days after birth, they also disappeared completely by 20 days. Epithelial cells showed a structure similar to those of the adult after weaning.

Study on the origin of apical tubules in ileal absorptive cells of suckling rats using concanavalin-A as a membrane-bound tracer

The ileal absorptive cells of suckling rats exhibit high levels of endocytic activity being engaged in nonselective uptake of macromolecules from the intestinal lumen. The apical cytoplasm usually contains an extensive network of small, membrane-limited tubules (apical tubules: AT), in addition to newly formed endocytic vesicles and large endocytic vacuoles. To determine whether the AT are directly involved in the endocytic process by carrying the tracer into the cell, we have analysed movements of the apical cell membrane of the ileal absorptive cells by using a membrane-bound tracer (horseradish peroxidase-labelled concanavalin-A: Con-A HRP). The ileal absorptive cells were exposed in vitro to Con-A HRP for 10 min at 4 degrees C, incubated for different times in Con-A free medium at 37 degrees C, and prepared for electron microscopy. After 1 min incubation at 37 degrees C, invaginations of the apical cell membrane, including coated pits, and endocytic vesicles were labelled with HRP-reaction product, whereas the AT and large endocytic vacuoles were negative. After 2.5 min, almost all the large endocytic vacuoles were labelled with reaction product, which was seen in their vacuolar lumen and along the luminal surface of their limiting membrane. A few AT with reaction product were seen in the apical cytoplasm; they were in frequent connection with the reaction-positive large endocytic vacuoles. With increasing incubation time, the number of the labelled AT increased. Thus, after 15 min at 37 degrees C, the apical cytoplasm was fully occupied by the reaction-positive AT. The ends of these AT were often continuous with small spherical coated vesicles. No reaction product was detected in the Golgi complex at any time after incubation. These observations indicate that the AT located in the apical cytoplasm probably originate by budding off from the large endocytic vacuoles, rather than being involved in the process of endocytosis.

Disaccharidase activity in intestine epithelium microvilli membranes of lambs during the first month after birth

Disaccharidase activity was studied in microvilli membranes of enterocytes isolated from duodenum, jejunum and ileum of lambs at an age of 1, 7 and 23 days. A maximum of lactase activity was observed on the 7th day compared to activity on 1st and 23rd day after parturition and a decrease in enzyme activity on the 23rd day compared to activity on the 7th day. Differences, however, were significant only in respect to activity in ileum. A significant increase of maltase activity in ileum and jejunum was established on the 7th and 23rd day compared to activity on the 1st day after parturition. Trehalase activity attained a maximum in all the three intestine divisions, consequently it subsided with no statistically significant differences. Lactase activity in ileum was significantly lower compared to activity in jejunum of lambs at an age of 1 and 23 days. A marked decrease of maltase activity in distal direction was found only on 1 day-old lambs. No significant alterations were observed in trehalase activity along the small intestine of lambs of the three age groups.

Biological and pathological aspects of the mammalian small intestinal permeability to macromolecules

The literature on the biology and pathology of mammalian small intestinal permeability to macromolecules is reviewed. In mammals, macromolecules may penetrate the epithelial layer of the small intestinal mucosa, especially in the neonatal period. The neonatal uptake and transport of immunoglobulins is important in the acquisition of passive immunity in the newborn. In the mature small intestine the uptake of macromolecules almost ceases, except in M-cells. Excessive uptake and transport of macromolecules has been demonstrated in several experimental and spontaneous gastrointestinal diseases, in which increased concentration of macromolecules in the small intestinal lumen and/or damage of one or more components of the small intestinal mucosal barrier is present. Finally, methods to study macromolecular permeation of the small intestine are discussed.

Ultrastructural localization of transferrin, transferrin receptor, and iron-binding sites on human placental and duodenal microvilli

Ultrastructural methods were used to determine the subcellular location of the transferrin receptor, transferrin and iron-binding sites on human term placenta and human duodenum microvillus surfaces. The transferrin receptor and transferrin were localized by immunocytochemical methods employing either OKT9, a human transferrin receptor monoclonal antibody, or mouse anti-human transferrin (ATfn), both followed by a horseradish peroxidase (HRP)-conjugated goat anti-mouse IgG (GAM-HRP) and diaminobenzidine (DAB) sequence. Iron-binding sites were localized by acid ferrocyanide (AF) staining after saturation of tissue specimens with iron, accomplished with iron nitrilotriacetate (FeNTA), a known transferrin iron donor. Placental microvillus surfaces demonstrated staining for the OKT9-GAM-HRP-DAB-reactive transferrin receptor, ATfn-GAM-HRP-DAB-reactive transferrin, and FeNTA-AF-reactive iron acceptor, whereas enterocyte microvillus surfaces lacked significant staining with each of these methods. FeNTA-AF stained iron-binding substance in placental and enterocyte microvilli and cytoplasmic matrix. Thus using the same ultrastructural immunostaining and cytochemical methods transferrin receptor, transferrin, and nitrilotriacetate iron acceptor sites can be demonstrated on the microvillus surface of human placenta but not on the microvillus surface of human duodena.

Receptor mechanisms of the neonatal intestine and their relationship to immunoglobulin absorption and disease

Immunoglobulin absorption by the calf has been the subject of considerable research. Despite these efforts little is known about the cytological events that occur at the level of the intestinal epithelial cell. These events have been studied extensively and characterized in the laboratory rodent; however, there have been few attempts to make corollaries between the two species. All neonatal animals display certain similarities in their intestinal morphology that may be correlated, with immunoglobulin absorption. Selectivity in absorption appears to be variable among neonatal animal species; however, all demonstrate some selectivity. Selectivity in absorption implies that receptors are a necessary component in the transport of immunoglobulins. Selectivity further requires binding of immunoglobulins to an endocytic vesicle membrane to ensure transport through the cell, circumvention of intracellular digestion, and release at the basolateral cell membrane. A decrease of immunoglobulin absorption may be accomplished in a variety of ways such as competition between intestinal microbes and immunoglobulins for a common receptor on the intestinal epithelial cell. An additional consideration is aberrant synthesis or recycling of the cell membrane receptor, as induced by metabolic decelerators such as cortisol. Failure to recycle immunoglobulin receptors also would decrease efficiency of absorption.

Histochemistry of oxidative metabolism in epididymal epithelium of mouse

The activities of cytoplasmic and mitochondrial dehydrogenases were assessed histochemically in the lining epithelia of five segments of the proximal part and the medial and distal parts of the mouse epididymis. The cytochemical evaluation of enzyme activities revealed by nitro BT or tetranitro BT was well supported by the relative transmittance values. In the principal cells of the proximal part, the activities of dehydrogenases differed according to histological segmentation. In the medial and distal parts of the duct, a progressive increase in the intensity of all the reactions was observed. The "goblet cells" with apical nuclei in the proximal part and the "clear cells" in the medial and distal parts showed higher activities than the adjacent principal cells.

Membrane-bound and fluid-phase macromolecules enter separate prelysosomal compartments in absorptive cells of suckling rat ileum

The absorptive cell of the suckling rat ileum is specialized for the uptake and digestion of milk macromolecules from the intestinal lumen. The apical cytoplasm contains an extensive tubulocisternal system, a variety of vesicles and multivesicular bodies (MVB), and a giant phagolysosomal vacuole where digestion is completed. To determine if sorting of membrane-bound and fluid-phase macromolecules occurs in this elaborate endocytic system, we infused adsorptive and soluble tracers into ligated intestinal loops in vivo and examined their fates. Lysosomal compartments were identified by acid phosphatase histochemistry. Native ferritin and two ferritin-lectin conjugates that do not bind to ileal membranes (Con A, UEAI) served as soluble tracers. Horseradish peroxidase binds to ileal membranes and thus was not useful as a fluid-phase tracer in this system. Cationized ferritin and a lectin that binds to terminal B-D-galactosyl sites on ileal membranes (Ricinus communis agglutinin [RCAI]-ferritin) were used as tracer ligands. All tracers entered the wide apical invaginations of the luminal cell surface and were transported intracellularly. Membrane-bound tracers were found in coated pits and vesicles, and throughout the tubulocisternal system (where cationized ferritin is released from the membrane) and later, in large clear vesicles and MVB. In contrast, fluid-phase tracers appeared within 5 min in vesicles of various sizes and were not transported through the tubulocisternae, rather, they were concentrated in a separate population of vesicles of increasing size that contained amorphous dense material. Large clear vesicles, large dense vesicles, and MVB eventually fused with the giant supranuclear vacuole. Acid phosphatase activity was present in MVB and in the giant vacuole but was not present in most large vesicles or in the tubulocisternae. These results demonstrate that membrane-bound and soluble protein are transported to a common lysosomal destination via separate intracellular routes involving several distinct prelysosomal compartments.

Influence of administered indigenous microorganisms on uptake of [iodine-125] gamma-globulin in vivo by intestinal segments of neonatal calves

Ten calves less than 14 h of age (average 8.6 h) were anaesthetized, and the intestine was ligated into segments 10 cm in length at 3-cm intervals beginning 1.8 m anterior of the ileocecal junction and proceeding proximally. Seven treatments were assigned in random order to segments in three successive sections of the small intestine. Segments received 1 ml of viable bacteria of intestinal origin, autoclaved bacteria of intestinal origin, or sterile microbiological broth at zero time; then after 4 h they were injected with iodine-125 labeled gamma-globulin. After an additional 1.5 h, the experiment was ended and uptake assayed. Two treatments measured anaerobic microbial growth after 4 h incubation with 1 ml of either sterile broth or live bacteria culture. Residual [iodine-125] gamma-globulin was measured in segments receiving 1 ml of sterile broth or live bacteria culture with 5.5-h incubation followed by 15-s exposure to labeled gamma-globulin. Uptake was lowest in segments receiving live bacteria as compared to segments receiving sterile inocula. Number of bacteria per gram of tissue was correlated negatively with uptake. Low corticosteroids in serum were associated with low uptake of gamma-globulin.

Colostral immunoglobulin transfer in calves II. The rate of absorption

The rate and pattern of colostral immunoglobulin absorption, based upon increase in concentration of immunoglobulin in serum in calves, has been determined from the interaction of three factors: starting age of colostral feeding, amount of colostrum fed, and time after feeding. All immunoglobulin classes show common characteristics of absorption following a rapid transfer during the first 4 h after feeding. An analysis of three-dimensional response surface for each of the three immunoglobulin classes indicated positive linear trend in the amount fed up to 2 liters. Rates of absorption in succeeding time periods following the initial feeding had decreasing linear trends. That is, age at first feeding had an inverse effect on rate of absorption. A linear-by-linear interaction between amount fed and starting age as shown for all three classes. Only immunoglobulin IgM had a significant quadratic response for amount fed. Concentration of immunoglobulin in the pooled colostrums fed had no influence on rate of absorption. Evidence is that 2 liters of colostrum fed to Holstein calves may be optimum in the range studied for maximum pinocytotic activation of absorptive cells and maximum rate of absorption.

Distributional uptake of gamma-globulin in small intestine of neonatal calves

Newborn calves deprived of colostrum were used to determine distribution of uptake of gamma-globulin labeled with iodine-125 in small intestine. Ten calves less than 12.5 h of age (average 7 h) were anesthetized, and intestines were exteriorized through an abdominal incision. Intestine was ligated into 10-cm segments, 70 cm apart, beginning at the ileocecal junction and progressing anteriorally, then each segment injected with 100 mg (appoximately 1 microCi) labeled gamma-globulin in 5 ml electrolyte solution, and incubated for 1.5 h. One additional segment was formed adjacent to segments 1, 5, and 10 to assess uptake after .5 h incubation with [iodine-125] gamma-globulin. After prescribed gamma-globulin exposure, segments were excised; then volume of lumen contents, segment weight, and tissue activity were measured. The location of each segment was the percentage of distance from cecum to abomasum. Uptake was milligrams gamma-globulin per gram of segment tissue. Distribution of gamma-globulin uptake after 1.5 h incubation was a cubic function of segment position. Uptake was greatest in a region 15% of the cecum-abomasum distance and declined progressively toward the abomasum. After .5-h incubation with gamma-globulin, regression of uptake on segment position was a quadratic function with greatest uptake at 30% of cecum-abomasum distance. Uptake was greater in segments exposed to gamma-globulin for 1.5 h than .5 h.

REgional functional differentiation in the gut of the grasscarp, Ctenopharyngodon idella (Val.)

A regional differentiation--reflecting structural differences--of the intestine of larval and juvenile grasscarps can be illustrated by studying the activity of alkaline phosphatase and the uptake of orally administered horseradish peroxidase. Pinocytosis takes place in a welldefined area of about 23% of the length of the gut (segment II). Neither the rostral +/- 68% (segment I) nor the caudal +/- 9% (segment III) shows absorption of the enzyme. Alkaline phosphatase activity, mainly localized at the microvilli of the enterocytes is high in the first segment of the gut and low in the second segment. In larvae, the activity decreases sharply at the transition from segment I to segment II. The activity is weak or absent in the caudal third segment. Quantitative histochemical data are confirmed by biochemical analyses. Alkaline phosphatase activity is found all over the mucosal folds of the first segment, with relatively weak activity at the base and at the tip of the folds. This may be related to a renewal of the epithelium. Our results suggest that active absorption of digested food takes place mainly in the rostral first segment, while the uptake of macromolecules by pinocytosis is a function of the second segment. Comparison of the results with information available in literature leads to a rejection of the hypothesis that the uptake of protein macromolecules in Cyprinids is to be attributed to the absence of a stomach and therefore to an inefficient digestion of proteins.

Influence of colostrum on transepithelial movement of Escherichia coli 055

The effect of colostrum on transepithelial migration of live Escherichia coli 055:B5:H7 in the neonatal calf intestine was determined by microbiological and microscopic investigations. Colostrum-deprived calves (2 to 6 h old) were given E. coli suspended in saline, E. coli suspended in colostrum, or E. coli in saline 1 h after colostrum. Twenty-four hours after exposure, tissues were collected for examination. Escherichia coli were numerous in mesenteric lymph nodes of calves given this organism in saline. Fewer were recovered from nodes of calves that received the bacteria in colostrum. Escherichia coli were not recovered from mesenteric lymph nodes of calves given colostrum before dosage with the organism. Electron microscopic studies of small intestines from calves that received E. coli in saline revealed bacterial attachment sites surrounded by exfoliation of microvilli. Bacteria appeared to enter epithelial cells by invagination of apical plasma membrane or dilation of apical tubules. Intracellular E. coli were enclosed in a surrounding membrane. The organisms were not observed adhering to or penetrating intestinal epithelium of calves that received E. coli in colostrum or 1 h after colostrum.

Absorption of horseradish peroxidase by the principal cells of the large intestines of postnatal developing rats

The absorption of horseradish peroxidase in the rat large intestine during the postnatal developing period was investigated by cytochemical and ultrastructural methods. In the ceca and ascending colons from 4-, and 5-day-old rats, intraluminaly injected peroxidase became localised on microvilli, in the intracytoplasmic network of the apical tubules and small vacuoles (tubulo-vacuolar system), in the large supranuclear vacuole, in the Golgi apparatus, on the lateral and basal cell membranes of the surface principal cells, and also in the lumen of blood capillaries in the subjacent propria. On the other hand, the protein tracer was not seen in the large intestinal epithelial cells that lack tubulo-vacuolar systems and large supranuclear vacuoles within their cytoplasm. In the descending colons of rats of any postnatal age, the epithelial principal cells are devoid of these membrane systems, and exogenous peroxidase was not detected in the cytoplasm of the principal cells. It is assumed that at least the proximal portion of the large intestine in neonatal animals has the capacity to absorb macromolecular protein through those surface principal cells that have specialized intracellular membrane systems.

Effect of potassium isobutyrate on absorption of immunoglobulins from colostrum by calves

Calves received either colostrum with 2.83 meq potassium isobutyrate per gram of gamma-globulin or colostrum with distilled water within 1 h after birth. Blood samples were taken at intervals during the first 72 h for determination of concentrations of gamma-globulin, immunoglobulin IgG and IgM. Calves fed colostrum with distilled water attained higher concentrations in serum of total gamma-globulin, immunolgobulin IgG and IgM. Holstein calves were more efficient than Ayrshire calves in absorbing total gamma-globulin, but differences between breeds were not significant for specific immunoglobulins. Efficiency of gamma-globulin absorption within 24 h was 35.7% for control calves and 24.7% for calves fed colostrum plus potassium isobutyrate. Potassium isobutyrate had a depressing effect on absorption of immunoglobulins by calves.

Electron microscopic study on gut epithelium of the tench (Tinca tinca L.) with respect to its absorptive functions

Few morphological differences are seen along the intestinal tract of the adult tench (Tinca tinca L.) a stomachless freshwater teleost. However, three segments can be distinguished, when function and structure of enterocytes are studied. The enterocytes of the proximal segment are found to be concerned with dietary lipids absorption. In the cell, absorbed fats are seen in two inclusion bodies: lipid particles and lipid droplets. Only lipid particles are involved in direct transport of absorbed fatty acids in the blood circulation, as in lymphatic vessels. Lipid droplets seem to be involved in temporary storage of fatty acids. Special features are found in enterocytes of the short middle segment; these cells show many invaginations and pinocytosis figures, a well-developed tubulo-vesicular network and large vacuoles in the supranuclear hyaloplasm. Such characters bear a resemblance to descriptions of the gut of some newborn mammals. The great permeability of this epithelium to macromolecules is demonstrated by the administration of horseradish peroxidase (HRP). Enterocytes of the distal segment show, at their basal pole, numerous invaginations of the plasma membrane, and a large mitochondrial population. Morphological similarity suggests a functional analogy with epithelia involved in water and ions transport.