The induction by muscle stimulation of a deep pectoral myopathy in the fowl

Thirty min occlusion of the subclavian artery of commercial strains of adult light-weight and broiler breeder fowls had no adverse effect on the supracoracoid muscle. When this temporary arterial occlusion was combined with electrically-induced contractions of the supracoracoid for a period of 4 min, myopathy occurred in both types of bird. A similar degree of muscle contraction without any interference with the arterial supply induced necrosis of the supracoracoid of the broilers but not of the light-weight strain. The superficial pectoral muscle of the broilers was not adversely affected by stimulation. The necrotic muscle resembled that in spontaneous deep pectoral myopathy. These findings are discussed with particular reference to the vascular supply to the muscle and although they are not considered to be due to pre-existing occlusive lesions of the arteries, the basic nature of the causative defect remains obscure. On the basis of this work carried out on commercial broiler breeder stock maintained at the Poultry Research Centre, we conclude that a relatively small number of electrically-stimulated contractions of the supracoracoid muscle will bring about necrotic myopathy.

Where, when and how much: regulation of myelin proteolipid protein gene expression

The myelin proteolipid protein (PLP) gene ( Plp) encodes the most abundant protein found in myelin from the central nervous system (CNS). Expression of the gene is regulated in a spatiotemporal manner with maximal levels of expression occurring in oligodendrocytes during the active myelination period of CNS development, although other cell types in the CNS as well as in the periphery can express the gene to a much lower degree. In oligodendrocytes, Plp gene expression is tightly regulated. Underexpression or overexpression of the gene has been shown to have adverse effects in humans and other vertebrates. In light of this strict control, this review provides an overview of the current knowledge of Plp gene regulation.

Functional characterization of a cis-acting DNA antisilencer region that modulates myelin proteolipid protein gene expression

Regulation of myelin proteolipid protein (PLP:) gene expression is tightly controlled, both spatially and temporally. Previously, we have shown with transgenic mice that a PLP:-lacZ fusion gene (which includes the entire sequence for PLP: intron 1 DNA) is regulated in a similar manner to endogenous PLP: gene expression. Furthermore, by deletion-transfection analyses using assorted PLP:-lacZ constructs with partial deletion of PLP: intron 1 sequences, we have shown that the first intron possesses an antisilencer region that is capable of over-coming repression mediated by two distinct regions located elsewhere within intron 1 DNA. Here, we report the ability of various fragments encompassing the antisilencer region to restore beta-galactosidase activity when inserted into PLP:-lacZ constructs, which originally exhibited low levels of beta-galactosidase activity. Additional constructs were generated to test the effects of these antisilencer-containing fragments in constructs that are missing either one or both of the negative regulatory regions that are overridden during antisilencing. Transfection analyses, in conjunction with protein-DNA binding assays, suggest that several nuclear factors are necessary for derepression of PLP: gene activity in an oligodendroglial cell line. Moreover, either the "core" or complete antisilencing region can act in an additive or synergistic fashion when multiple copies are inserted into the Plp-lacZ constructs.

Myelin proteolipid protein intron 1 sequences do not appear to enhance myelin proteolipid protein gene transcription

Sequences from the first intron of the mouse myelin proteolipid protein (PLP) gene were examined for their ability to modulate PLP gene expression. Glial (N20.1) or nonglial (NIH 3T3) cells were transiently transfected with constructs that contained 1.4 kb of PLP promoter sequence driving luciferase reporter gene expression, as well as various portions of PLP intron 1 DNA. Although these same PLP intron 1 fragments enhanced reporter gene expression from a heterologous basal promoter in a previous study, the results reported here demonstrate that they do not augment PLP promoter activity. Thus, the regulation of PLP cell-type-specific expression, conferred by the first intron, appears to be mediated by an enhancer-independent mechanism.

Antisilencing: myelin proteolipid protein gene expression in oligodendrocytes is regulated via derepression

Antisilencer or antirepressor elements have been described, thus far, for only a few eukaryotic genes and were identified by their ability not to augment gene expression per se but to override repression mediated via negative transcription regulatory elements. Here we report the first case of antisilencing for a neural-specific gene, the myelin proteolipid protein (PLP) gene (Plp). PLP is the most abundant protein found in CNS myelin. The protein is synthesized in oligodendrocytes, and its expression is regulated developmentally. Previously we have shown that a PLP-lacZ transgene (which includes the entire sequence for Plp intron 1) is regulated in mice, in a manner consistent with the spatial and temporal expression of the endogenous Plp gene. In the present report, we demonstrate by transfection analyses, using various PLP-lacZ deletion constructs, that Plp intron 1 DNA contains multiple elements that collectively regulate Plp gene expression in oligodendrocytes. One of these regulatory elements functions as an antisilencer element, which acts to override repression mediated by at least two negative regulatory elements located elsewhere within Plp intron 1 DNA. The mechanism for antisilencing appears to be complex as the intragenic region that mediates this function binds multiple nuclear factors specifically.

Regulation of murine myelin proteolipid protein gene expression

To identify putative sequences that direct cell type-specific expression and/or enhance proteolipid protein (PLP) gene expression, glial or nonglial cells were transfected with various PLP-luciferase constructs that collectively span the entire mouse PLP-specific DNA present in a transgene known to direct cell type specificity in transgenic mice. These constructs were transfected into murine oligodendrocyte cell lines that transcribe the PLP gene and, hence, should contain the requisite trans-acting factors necessary for PLP gene expression. Mouse NIH/3T3 fibroblasts were used as a nonglial model. We have finely mapped the PLP promoter region for transcriptional regulatory elements and demonstrate both positive and negative elements, none of which appear to extinguish expression in nonglial cells. The 5'-flanking PLP DNA tested did not enhance the basal herpes simplex-1 virus thymidine kinase (TK) promoter, nor did PLP sequences present in the distal half of intron 1. The 5' portion of intron 1 did enhance TK promoter activity, suggesting that this region of the gene may contain enhancer elements that modulate PLP gene expression; however, the enhancement did not appear to be cell type-specific. Intriguingly, a 541 bp region of the intron that significantly enhanced TK promoter activity contains multiple JC virus repeated elements and other elements known to be important in restricting the virus to oligodendrocytes. These results suggest that intron 1 sequences may modulate expression of the PLP gene.

The first intron of the myelin proteolipid protein gene confers cell type-specific expression by a transcriptional repression mechanism in non-expressing cell types

Chimeric genes containing portions of the mouse myelin proteolipid protein (PLP) gene fused to the lacZ reporter gene were used to detect the effect of PLP intron 1 sequences on cell type-specific expression. A transfected fusion gene containing PLP intron 1 sequences was expressed in an oligodendrocyte cell line but not in a liver cell line, consistent with endogenous PLP gene expression. However, an analogous fusion gene missing the first intron was expressed in either oligodendrocyte or liver transfected cells. These studies suggest that transcriptional repressor element(s) located in PLP intron 1 are important in extinguishing expression in non-glial cell types and that the promoter alone functions in an indiscriminate manner. This moderately large intron (>8 kb) was sequenced to aid in future fine mapping of these cell-specific regulatory element(s).

Dual luminescence-based reporter gene assay for luciferase and beta-galactosidase

A unique combined luminescence assay for firefly (Photinus pyralis) luciferase and beta-galactosidase (beta-gal) reporter gene products is described. Luciferase and beta-gal activities are determined with the same aliquot of cell lysate prepared from cells contransfected with both reporter genes, thereby reducing manual labor and increasing experimental accuracy. With the Dual-Light assay system, luciferase activity is measured first with an enhanced luciferase assay, followed by quantitation of beta-gal with Galacton-Plus chemiluminescent substrate and Sapphire-II enhancer. Highly sensitive detection of luciferase (2 fg) and beta-gal (8 fg) is achieved with a dynamic range over seven orders of magnitude of enzyme concentration. Comparative analysis of both independent and combined (Dual-Light) detection methods for cells contransfected with luciferase and beta-gal reporter genes is also described.

A myelin proteolipid protein-LacZ fusion protein is developmentally regulated and targeted to the myelin membrane in transgenic mice

Transgenic mice were generated with a fusion gene carrying a portion of the murine myelin proteolipid protein (PLP) gene, including the first intron, fused to the E. coli LacZ gene. Three transgenic lines were derived and all lines expressed the transgene in central nervous system white matter as measured by a histochemical assay for the detection of beta-galactosidase activity. PLP-LacZ transgene expression was regulated in both a spatial and temporal manner, consistent with endogenous PLP expression. Moreover, the transgene was expressed specifically in oligodendrocytes from primary mixed glial cultures prepared from transgenic mouse brains and appeared to be developmentally regulated in vitro as well. Transgene expression occurred in embryos, presumably in pre- or nonmyelinating cells, rather extensively throughout the peripheral nervous system and within very discrete regions of the central nervous system. Surprisingly, beta-galactosidase activity was localized predominantly in the myelin in these transgenic animals, suggesting that the NH2-terminal 13 amino acids of PLP, which were present in the PLP-LacZ gene product, were sufficient to target the protein to the myelin membrane. Thus, the first half of the PLP gene contains sequences sufficient to direct both spatial and temporal gene regulation and to encode amino acids important in targeting the protein to the myelin membrane.

Mutations in the myelin proteolipid protein gene alter oligodendrocyte gene expression in jimpy and jimpymsd mice

The mouse myelin proteolipid protein (PLP) gene has been studied in normal and jimpymsd mice. Potential upstream regulatory regions of the normal gene have been cloned and mapped, but when these regions were studied in jimpymsd mice by Southern blots, no alterations were observed, relative to the normal gene. To assess whether the low ratio of PLP to DM20 proteins in this mutant reflected an altered PLP/DM20 ratio mRNAs, S1 nuclease analyses were undertaken, which demonstrated that at all ages studied in both jimpy and jimpymsd mice, PLP mRNA was elevated above DM20 mRNA. When exon 3 (the site of the alternative splice signal for DM20 mRNA) of the jimpymsd PLP gene was sequenced, no mutation was identified. The transcription of the PLP gene in normal and mutant animals was studied. The transcription rate increases in normal animals with development, and in very young jimpymsd or jimpy mice, the transcription rate of the PLP gene was close to that of age-matched normal animals. However, by 10 days of age, the transcription rate of this gene in both mutants was significantly below that of age-matched controls. The transcription rate of the myelin basic protein (MBP) gene was also reduced, indicating that expression of both genes is affected by this mutation. In contrast, the transcription rate of the glycerol phosphate dehydrogenase (GPDH) gene, an early marker of oligodendrocytes, is equal to or greater than normal in both mutants. We have confirmed an earlier report of a point mutation in exon 6 of the jimpymsd PLP gene, which converts an alanine to a valine.(ABSTRACT TRUNCATED AT 250 WORDS)

Sequences essential for activity of the thyroid hormone responsive transcription stimulatory element of the rat growth hormone gene

Thyroid hormone dependent transcription stimulatory and inhibitory elements exist at the 5'-end of the rat GH (rGH) gene (TSE and TIE, respectively). In this study, the location of the sequences essential for TSE activity was examined using stably transfected GC cells. Because the TIE may influence TSE activity, we investigated TSE activity both on the rGH promoter, in the presence of the TIE, and on the viral thymidine kinase promoter, with the TIE deleted. The results of these studies indicate that the minimum sequences essential for TSE activity exist between positions -194 and -169 of the rGH gene.

Role of glucosinolates in the causation of liver haemorrhages in laying hens fed water-extracted or heat-treated rapeseed cakes

Glucosinolates were removed from whole rapeseed by a hot-water extraction procedure or depleted by heat treatment. When laying hens were maintained for three months on diets containing about 300 g kg-1 of these rapeseed cakes, the incidence of liver haemorrhages detected at post mortem examination was similar to that in birds maintained on 300 g kg-1 commercial rapeseed meal and significantly greater than in control birds fed soya-based diets. The effectiveness of glucosinolate extraction or depletion was determined by chemical analysis and by histological examination of the thyroid glands. Histologically the haemorrhages were similar after feeding extracted and commercial rapeseed meals. Diets containing mixtures of nitriles and glucosinolates severely depressed food intake and egg production but did not cause a greater incidence of haemorrhages than the other rapeseed products tested. Mortality from causes other than liver haemorrhage was higher with the diets containing rapeseed and this suggests that rapeseed has a more generalised effect on the body's defence mechanisms. These observations suggest that other factors in rapeseed meal, alone or acting with glucosinolates, may be responsible for inducing liver haemorrhages in laying hens.

Experimental systems which modify and simulate rapeseed-induced liver haemorrhages in in-lay hens

The occurrence of liver haemorrhages was compared when diets containing 30 or 40 per cent rapeseed meal (RSM) or 30 per cent soybean meal (SBM), with and without experimental additives, were fed to in-lay hens of a commercial egg-producing strain for 12 weeks. The incidence of haemorrhages was significantly greater when the birds were maintained on the basal (unsupplemented) RSM diet than on the equivalent SBM diet. Haemorrhages were either small and infrequent, minute and multiple as in peliosis hepatis, or large enough to rupture the liver capsule. They might be recent or old and encapsulated, sometimes both varieties affecting the same specimen, and they occurred in any part of the liver. Histologically, hepatocyte necrosis and reticulin derangement were not detected in livers without gross haemorrhages and even in those with haemorrhages these abnormalities were only seen closely adjacent to haemorrhages or to foci of eosinophilic fibrinoid. In some instances there was sinusoidal ectasia. Separate additions of 50 g dried skimmed milk powder, 0.5 g zinc oxide, 0.25 g ferrous sulphate or 2.0 mg selenium (as sodium selenite) kg-1 to the basal RSM diet did not significantly modify the incidence of haemorrhage. Ferrous sulphate slightly reduced goitrogenicity. Supplements of 2.2 mg menadione and 1.0 g sodium phenobarbital kg-1 RSM diet induced slight reductions in the number of cases of liver haemorrhage or their severity, indicating that the multifunction oxidase system may be involved in rapeseed hepatotoxicity. The addition of 0.5 g methimazole kg-1 to the basal SBM diet induced severe colloid goitre but did not induce liver haemorrhage. Both thiouracil (0.5 g kg-1 diet) and beta-aminopropionitrile (0.5 g and 2.5 g kg-1 diet) when added to the basal SBM diet induced liver haemorrhages which did not differ in incidence or histological appearance from those induced by RSM. Hyperplastic goitre was caused by thiouracil. Intrahepatic cholestasis induced by sodium taurolithocholate, bilirubin and alpha-naphthylisothiocyanate and extrahepatic cholestasis induced by bile duct ligation resulted in hepatocyte necrosis but not gross liver haemorrhages. Spontaneous deaths due to conditions other than liver haemorrhages were significantly more numerous in RSM-fed than SBM-fed hens.(ABSTRACT TRUNCATED AT 400 WORDS)

Discrete positive and negative thyroid hormone-responsive transcription regulatory elements of the rat growth hormone gene

We have recently shown that a thyroid hormone-responsive transcription stimulatory element exists in the 5'-flanking DNA near the rat growth hormone (rGH) gene (Crew, M. D., and Spindler, S. R. (1986) J. Biol. Chem. 261, 5018-5022). Progressive deletion-transfection analysis of the 5' end of the gene has led to the identification of two genetic elements responsive to thyroid hormone. The first of these is a thyroid hormone-responsive transcription stimulatory element, or TSE. The TSE induced a thyroid hormone-dependent induction-attenuation transcription cycle similar to that of the natural rGH gene. Deletion of sequences between positions -254 and -241 in the rGH 5'-flanking DNA eliminated TSE activity. The second regulatory element is a thyroid hormone-responsive transcription inhibitory element (TIE). When this element was active, thyroid hormone strongly but transiently inhibited rGH promoter utilization. Deletion of sequences between nucleotides -46 and -21 abolished the effects of the TIE. To determine whether the TSE and TIE are enhancer-like, we ligated various regions of rat growth hormone 5'-flanking DNA containing these elements to a chimeric test gene containing the Herpes simplex virus thymidine kinase promoter. Thyroid hormone activated heterologous promoter utilization when a rat growth hormone 5'-flanking DNA fragment containing the TSE (-520 to -115) was linked in cis, regardless of the distance or orientation of the TSE with respect to the promoter. These data suggest that the TSE is a thyroid hormone-dependent enhancer. In contrast, when the TIE was placed immediately 5' to the thymidine kinase promoter, transcription was not effected by 3,5,3'-L-triiodothyronine, suggesting that the TIE is not enhancer-like.

Liver haemorrhages induced by rapeseed meal: incidence in adult male and female fowls

Adult cockerels of a commercial egg-producing strain did not develop liver haemorrhages when maintained for 12 weeks on a diet containing 400 g rapeseed meal/kg food. Haemorrhages occurred in 43% of laying hens of the same strain as the cockerels and 33% of laying hens of another strain maintained on the same diet for the same period. Oestrogenisation of the male birds did not influence the incidence of haemorrhage.

Hemiagenesis of the thyroid gland in the quail (Coturnix coturnix japonica)

Hemiagenesis of the thyroid occurred in a closed population of Japanese quails. The unilateral gland was histologically normal, occurred most frequently in females, was heavier than individual pairs of glands and the birds showed no clinical effects. Comparative aspects are discussed.

Elevated bile acids in the plasma of laying hens fed rapeseed meal

A simple procedure was developed for the estimation of bile acid taurine conjugates in fowl plasma. Laying hens fed a diet containing rapeseed meal (RSM) (400 g kg-1) for 12 weeks had higher bile acid levels (154 mumol litre-1) than hens fed a control soyabean diet (116 mumol litre-1) (P less than 0.01). The incidence of liver haemorrhages was higher (34.8 per cent) in RSM-fed hens than in controls (21 per cent), but the severity of the lesions did not correlate with the bile acid concentration in affected birds. Histological examination of sections from livers of RSM-fed birds did not reveal significant hepatocyte degeneration outside the immediate vicinity of the haemorrhage. Canalicular bile plugs were never seen. The incidence of liver haemorrhages (13 per cent) and plasma bile acids (85 mumol litre-1) were lower in hens fed a diet containing beta-aminopropionitrile (0.5 g kg-1), a known lathyrogen. Acute treatment of hens with the hepatotoxin alpha-naphthyl isothiocyanate over four days induced necrosis of hepatocytes and resulted in elevated bile acid concentrations (262 mumol litre-1) compared with controls (73 mumol litre-1) given arachis oil. It was concluded that laying hens fed high levels of RSM develop cholestasis but the toxic principle is not known.

Ectopic pulmonary cartilage and bone in domestic fowl

The occurrence and histological appearance of ectopic pulmonary cartilage and bone in domestic fowl was investigated. Its incidence was shown to vary in different strains of birds. The structures may occur in newly hatched chicks and are similarly present in birds maintained on diets containing bonemeal and diets without it. They could not be experimentally induced by bronchial insufflation of fine bone particles. Previous theories of their genesis are discussed and it is concluded that they do not originate from either inhaled dietary bonemeal or disease processes but are probably abnormal embryonic induction of mesenchyme or cartilaginous germ cells displaced from adjacent bronchi.

A computer method for scanning and analysis of dot blots

A system is described for computer analysis of autoradiograms produced from dot blots. The autoradiograms are first digitized on a rotating drum densitometer. The system automatically locates, integrates, and corrects the intensity of each spot for background. A linear range of exposures for each series of dilutions on the dot blot is calculated, and the amount of specific RNA is reported relative to other samples or to an internal standard. Without operator intervention, the system can directly scan and analyze all possible spots produced by the commercial filtration devices which use the geometry of a 96-well microtiter plate.

X chromosome-linked muscular dystrophy (mdx) in the mouse

An X chromosome-linked mouse mutant (gene symbol, mdx) has been found that has elevated plasma levels of muscle creatine kinase and pyruvate kinase and exhibits histological lesions characteristic of muscular dystrophy. The mutants show mild clinical symptoms and are viable and fertile. Linkage analysis with four X chromosome loci indicates that mdx maps in the Hq Bpa region of the mouse X chromosome. This gives a gene order of mdx-Tfm-Pgk-1-Ags, the same as for the equivalent genes on the human X chromosome.

Toxic effects of high concentrations of zinc oxide in the diet of the chick and laying hen

The effects of high dietary concentrations of zinc oxide on chicks and hens were studied in four experiments. Chicks given 2000, 4000 or 6000 mg zinc/kg diet from 2 to 6 weeks of age grew poorly, many showing gizzard erosion and lesions of the exocrine pancreas. Dissecting aneurysms occurred in a few birds receiving 6000 mg zinc/kg. Pancreatic lesions were found in chicks maintained on 1000, 2000 or 4000 mg zinc/kg from 0 to 4 weeks and the two higher concentrations reduced body weight and increased the incidence of gizzard erosion. Histologically, gizzard lesions varied from excessive desquamation of epithelial cells, heterophils and erythrocytes into an abnormally spongiform koilin, to erosion of koilin, glands and pits. Pancreatic lesions could be detected only microscopically and consisted of dilation of the acinar lumina, cytoplasmic vacuolation, cytoplasmic globule formation and necrosis of the exocrine cells with interparenchymal fibrosis. Similar lesions of the gizzard and pancreas were found in hens after they had received 10000 or 20000 mg zinc/kg diet for only 4 d. Hens given 10000 mg zinc/kg for 4 d followed by a normal zinc intake for 28 d had normal gizzards and pancreata.

The contribution of anorexia to reduced growth in zinc-deficient chickens

1. It was shown, using a paired-feeding technique, that the growth depression in zinc-deficient chicks was largely caused by the greatly reduced consumption of the deficient diet. 2. Chicks receiving a zinc sulphate solution directly into the crop ate an amount of zinc-deficient diet similar to that of the zinc-deficient diet eaten ty the control chicks; palatability was thus ruled out as the cause of the anorexia. 3. Only chicks receiving the zinc-deficient diet displayed signs of zinc deficiency.

The effects of zinc deficiency on oral behaviour and taste bud morphology in chicks

The number of beak and tongue movements was measured in chickens (Gallus domesticus) following oral stimulation with different concentrations of quinine hydrochloride (0.01 to 0.25 M), acetic acid (0.25 to 5.0 M), sodium chloride (0.5 to 5.0 M) and distilled water. The birds showed an increase in behaviour with increasing concentration up to a certain point, when the response showed no further increase. 2. Two groups of chicks, one fed on a normal diet and one fed on a diet deficient in zinc, were stimulated orally every 3 to 4 d with 0.1 ml of sodium chloride (2 M), acetic acid (2 M), quinine hydrochloride (0.1 M) and water, and the numbers of beak and tongue movements were recorded. 3. All the birds fed on the zinc-deficient diet showed significant increases in beak and tongue movements compared with the control birds. The time of onset of this increase in behaviour was variable: with quinine hydrochloride it was 3 d whereas with acetic acid, sodium chloride and water it was between 6 and 9 d. 4. The morphology of the taste buds in zinc deficiency was investigated and there was no evidence of primary or preferential involvement of the taste buds; these structures were either morphologically normal or were involved in a generalised degeneration of the epithelium. 5. The increase in oral behaviour is discussed in relation to the possible ageing of the taste cells and to the general degeneration of the oral epithelium.

March gangrene: deep pectoral myopathy, Oregon disease, green muscle disease

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Pathology of deep pectoral myopathy of broilers

Deep pectoral myopathy occurred in 39 of 204 apparently healthy and 46 of 146 ill, adult broiler breeders from Poultry Research Centre flocks. Both sexes and two commercial strains were similarly affected. The myopathy was not associated with any disease except pododermatitis. The supracoracoid was the only muscle affected. It was bilaterally involved in 33 chickens. The lesions were grouped macroscopically into three categories: acute oedema progressing to a green necrosis, centrally located cicatrix, and replacement of the caudal region by fibroadipose tissue. Microscopcially the green lesion consisted of necrotic, anucleate muscle fibres devoid of inflammatory cells and surrounded by a fibrous capsule that had a reactive inner border and externally abutted on normal and regenerating muscle or fibro-adipose tissue. Considered with the ultrastructural findings of early loss of glycogen and disintegration of sarcoplasmic reticulum, mitochondria, nuclei and Z lines, these findings indicate that the condition is an ischaemic necrosis. There was no evidence that its primary cause was occlusive vascular lesions. The muscle was able to regenerate unless extensive secondary neurological lesions were present.

Deep pectoral myopathy: an experimental simulation in the fowl

Surgical occlusion of the subclavian artery of domestic fowls has been found to induce a condition closely resembling, in location and histopathology, the deep pectoral myopathy of turkeys. The operative procedure is described and the significance of the collateral blood supply in the pathogenesis of the lesion is briefly discussed.

Changes in plasma lipid and glucose levels during the onset of fatty liver and kidney syndrome in chics

Plasma glucose, free fatty acid and triglyceride levels were measured during the onset of fatty liver and kidney syndrome in chicks. Intial studies indicated that behavioural and clinical changes characteristically associated with the syndrome were observed only during the 24 h preceding death. A more detailed examination of the blood changes was made on fasted birds. Typically, affected birds could be distinguished from healthy fasted birds by a hypoglycaemia which developed within 2.5 h of the removal of food, and a slightly higher and more sustained elevation of free fatty acid levels. Triglyceride values were not generally different from those found in normal birds. Although moderate to large amounts of lipid were occasionally observed in the kidneys of healthy fasted birds, only in affected birds was significant lipid infiltration of the kidneys associated with a similar level of lipid infiltration of the liver. In extreme cases death from fatty liver and kidney syndrome could occur within 4 h of the removal of food.

The histopathology of zinc deficiency in ducks

Ducks maintained from hatching on zinc-deficient diets were retarded in growth and had severe lesions of the pedal epidermis, epithelia of the base of the tongue, oral surface of the larynx and nasal sinuses. Similar but milder changes affected the roof of the mouth, the crop and the oesophagus of a few cases. There was derangement of the architecture of the rete mucosum with loss of distinction between the cells of the stratum basale and stratum spinosum. Enlargement of the nuclei and nucleoli of these cells, widening of the intercellular space and dyskeratosis and degeneration, particularly of the prickle cells, were seen. Although epithelial atrophy occurred in early examples of the condition, acanthosis, hyperkeratosis and heterophil infiltration of the epithelial layers were characteristic of most cases. Erosion of the epithelium with the formation of purulent crusts ocntaining secondary bacterial foci was present and in these cases inflammatory phenomena occurred in the dermis. A small proportion of the nuclei of the pancreatic exocrine cells were enlarged and irregular in shape.

An ultrastructural study of the liver, kidney and myocardium in the fatty liver and kidney syndrome in the fowl

In birds with the fatty liver and kidney syndrome large lipid droplets measuring up to 4 mum in diameter were observed in increased numbers in liver, kidney and heart muscle, particularly in the livers and the proximal convoluted tubules (PCT) of the kidneys. In the hepatocytes and the PCT a much smaller type of lipid particle (LP) was also observed, both intracellularly within the cisternae of the Golgi-ER system and outside the plasma membranes in the space between neighbouring parenchymal cells, within the space of Disse and among the basal processes of the PCT. The origin of these LP is discussed.

Biotin deficiency and fatty liver and kidney syndrome in chicks given purified diets containing different fat and protein levels

1. The occurence of biotin deficiency and fatty liver and kidney syndrome (FLKS) in chicks was studied using a 2x2x2x2 factorial-design experiment in which the variables were dietary biotin, fat and protein, and starvation. 2. The severity of biotin deficiency, using growth retardation and severity of dermal lesions as criteria, was least when the low-biotin diet also contained low levels of fat and protein. Addition of fat or protein increased the severity of the deficiency. Tissue fatty acid composition was affected by biotin deficiency only in those birds given the low-protein, low-fat diet. The main change was an increase in the ratio, 16:1 fatty acids :18:0 fatty acids. Plasma glucose and free fatty acid levels in non-fasted birds were unaffected by the dietary variables. 3. Mortality from FLKS with the diet containing low biotin, fat and protein levels was 52% at 28d, but was reduced or eliminated when the dietary level of any of these ingredients was increased. 4. Starvation considerably increased the incidnece of FLKS in the period immediately after fasting, and also affected plasma glucose and free fatty acid concentrations. Liver fatty acid composition, indicated an increase in the proportion of 18:0 at the expense of 16:1 and concentrations increased in proportion, at the expense of 18:0. 5. The relationship between biotin deficiency and FLKS, and a possible mechanism for the induction of FLKS by starvation are discussed.

The occurrence of lipid in the oxyntico-peptic cells of the proventriculus of the fasting domestic fowl

A histological study has shown that considerable amounts of lipid accumulate in the oxyntico-peptic cells of the proventriculus of domestic fowls deprived of food. Lipid droplets were first seen in the cells 6 hours after commencing the fast and they reached a maximum in 24 hours; a decrease was detected histologically 2 hours after re-feeding and all lipid had disappeared 8 hours after access to food. Lipid was observed in fasted chickens aged from 1 to 27 weeks, in four different breeds, and in certain naturally occurring diseases. Small amounts of lipid were also seen in the proximal convoluted tubules of the kidneys of chickens which had been fasted. The relationship of the lipid to the metabolism of the oxyntico-peptic cells and to certain disease states is discussed.

The histopathology of fatty liver and kidney syndrome in chicks

Studies of the general histopathology of the fatty liver and kidney syndrome in chickens have shown abnormal accumulations of the lipid in a variety of organs but no degenerative or inflammatory reactions. Lipid was found in some skeletal muscles, alimentary tract, autonomic ganglia, central nervous system and pineal gland as well as in the liver, kidney and heart. Small amounts of lipid were sometimes seen in the exocrine pancreas, adrenal medulla and epithelium of the thyroid follicles. Lipid deposits in the liver were primarily associated with the hepatic structural unit. The glycogen content of the hepatic cell was reduced. The lipid-metabolising gastrocnemius muscle contained abnormal amounts of lipid but this did not apply to the carbohydrate-metabolising pectoralis major muscle. The thymus did not contain excessive lipid but was significantly smaller in affected than in control birds of similar ages. There was loss of tinctorial distinction between the cortex and medulla of the adrenal gland associated with decreased basophilia of the latter region. Many of these morphological changes can be correlated with previously reported biochemical findings and they are discussed in relation to the hyperlipaemia and hypoglycaemia which characterise the disease.

The Harderian glands of the domestic fowl. 3. Ultrastructure

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The Harderian glands of the domestic fowl. II. Histochemistry

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The Harderian gland of the domestic fowl. I. Histology, with reference to the genesis of plasma cells and Russell bodies

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The histochemistry of the pineal gland of the domestic fowl

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