Low incidence of atrial septal defects in nonmammalian vertebrates.

The atrial septum enables efficient oxygen transport by separating the systemic and pulmonary venous blood returning to the heart. Only in placental mammals will the atrial septum form by the coming-together of the septum primum and the septum secundum. In up to one of four placental mammals, this complex morphogenesis is incomplete and yields patent foramen ovale. The incidence of incomplete atrial septum is unknown for groups with the septum primum only, such as birds and reptiles. We found a low incidence of incomplete atrial septum in 11 species of bird (0% of specimens) and 13 species of reptiles (3% of specimens). In reptiles, there was a trabecular interface between the atrial septum and the atrial epicardium which was without a clear boundary between left and right atrial cavities. In developing reptiles (four squamates and one crocodylian), the septum primum initiated as a sheet that acquired perforations and the trabecular interface developed late. We conclude that atrial septation from the septum primum only results in a low incidence of incompleteness. In reptiles, the atrial septum and atrial wall develop a trabecular interface, but previous studies on atrial hemodynamics suggest this interface has a very limited capacity for shunting.

Wing Abnormality in a Wild-Hatched Whooping Crane (Grus americana) Chick from the Nonmigratory Population in Louisiana, USA.

We describe a wing abnormality in a wild-hatched Whooping Crane (Grus americana) chick from the reintroduced Louisiana, US nonmigratory population. Despite its seemingly compromised flight ability, the chick fledged, reached independence, and lived until 13 mo of age. Necropsy revealed an axial malunion near the left carpus likely resulting from trauma.

Bilateral Pentadactyly in an Immature Alpine Swift (Tachymarptis melba).

An immature Alpine swift (Tachymarptis melba) that presented to a wildlife rehabilitation center was observed to have bilateral pentadactyly on examination. The supernumerary digits did not appear to cause discomfort for the bird, and no motor deficits were apparent. The skin and nails of the digits appeared normal. Radiographically, the extra digits appeared to be composed of two phalanges. The male swift was housed and fed an insectivore diet until it was fully fledged and demonstrated good flying ability. After 16 days of hospitalization, hand-feeding, and flight training, the bird was released to the wild. To our knowledge, this is the first case described of bilateral pentadactyly in an Alpine swift.

A four-legged hen with two cloacae and three caeca

Here we report a fourteen-month-old fourleggedlocal hen in Nigeria with two cloacae and three caeca. The hen walked with only the normal two limbs, which were larger and cranial to the extra two limbs. The extra limbs were usually suspended in the air and pointed caudally during motion, being attached to the pygostyle by cartilage and skin tissue. Investigations of the bird were carried out using radiology ,necropsy findings and biometry. The intestines occupied the caudodorsal portion of the abdominal cavity with three caeca attached at the terminal end of the ileum; two on the right side of the median plane and one on the left. The right caecum was fused and had a divided distal end, terminating in two blind sacs. The hen had two cloacal openings, one on each side of the median plane and was observed to consistently defecate only through the right. The findings from our work provide information on multiple development alabnormalities in the hen (AU)

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Overview of developmental heart defects by dioxins, PCBs, and pesticides.

The developing cardiovascular system is a sensitive target of many environmental pollutants, including dioxins, dioxin-like polychlorinated biphenyls (PCBs), and some pesticides such as methyl parathion. Laboratory research has utilized a variety of vertebrate models to elucidate potential mechanisms that mediate this cardioteratogenicity and to establish the sensitivity of different species for predicting potential risk to environmental and human health. Studies of dioxin and dioxin-like PCBs have illustrated that piscine, avian, and mammalian embryos exhibit cardiovascular structural changes and functional deficits, although the specific characteristics vary among the individual models. Piscine models typically exhibit reduced blood flow, altered heart looping, and reduced heart size and contraction rate. The chick embryo exhibits extensive cardiac dilation, thinner ventricle walls, and reduced responsiveness to chronotropic stimuli, while the murine embryo exhibits reduced heart size. It is notable that in all models the dioxin-associated cardioteratogenicity is associated with increases in cardiovascular apoptosis and decreases in cardiocyte proliferation. While the cardiotertogenicity in piscine and avian species is associated with overt morbidity and mortality, that is not the case for the murine embryo. However, murine offspring exposed during development to dioxin exhibit cardiac hypertrophy and an increased sensitivity to a second cardiovascular insult in adulthood. Thus, although the mammalian embryo is less sensitive to cardiovascular defects by dioxin and dioxin-like compounds, developmental exposure increases the risk of cardiovascular disease later in life. The impact of developmental exposure to dioxin-like chemicals on human cardiovascular disease susceptibility is not known. However, recent animal research has confirmed human epidemiology studies that dioxin exposure in adulthood is associated with hypertension and cardiovascular disease.

An overview of dioxin-like compounds, PCB, and pesticide exposures associated with sexual differentiation of neuroendocrine systems, fluctuating asymmetry, and behavioral effects in birds.

Dioxin, polychlorinated biphenyls (PCBs), and pesticides impact neural systems in birds due to interference with sexual differentiation. Early endocrine disrupting chemical (EDC) effects may delay maturation and have long-term effects on lifetime reproduction, especially in precocial birds that complete sexual differentiation prior to hatch. Semi-altricial and altricial species appear more resilient to EDC effects and show a gradient in sensitivity, especially in the neuroplastic song system. Embryonic steroid exposure occurs via maternally deposited steroids followed by embryo produced hormones; EDCs potentially affect these developing systems. As such, EDCs can impact lifelong fitness by acting on neural systems that regulate reproduction, metabolism, and behavior.

Reporte de albinismo en Podiceps major, Pelecanus thagus y Cinclodes fuscus y revisión de aves silvestres albinas del Perú / Report of albinism in Podiceps major, Pelecanus thagus y Cinclodes fuscus and a revision of wild albino birds from Peru

Reportamos observaciones de individuos albinos en tres especies de aves peruanas, el Zambullidor Grande (Podiceps major), el Pelícano peruano (Pelecanus thagus) y el Churrete cordillerano (Cinclodes fuscus). Los individuos eran albinos parciales casi totalmente blancos, aparentemente adultos, que mostraron un comportamiento normal entre sus conespecíficos. La supervivencia después de varios meses pudo ser comprobada para el Pelícano peruano y el Churrete cordillerano. Debido a que la información publicada sobre albinismo en aves peruanas es muy escasa, se realizó una revisión y se recopilaron registros para otras nueve especies que son también presentados.

We report observations of albino individuals in three species of Peruvian birds, Great Grebe (Podiceps major), Peruvian Pelican (Pelecanus thagus) and Bar-winged Cinclodes (Cinclodes fuscus). These were all three mostly white partial albinos, apparently adult birds that showed normal behavior among normal conspecific individuals. Survival after several months was confirmed for the Peruvian Pelican and the Bar-winged Cinclodes. Since published information on albinism in Peruvian birds is very scarce, a revision was made and records for nine other species were compiled and are also presented.

Three anomalies: A scythebill in the Greater Antillean Grackle (blackbird), a crown pattern in the Rock Beauty (angelfish), and a double spot in the Butter Hamlet (grouper), and their possible genetic significance / Tres anomalías: un pico de guadaña en Greater Antillean Grackle (mirlo), un patrón de corona en Rock Beauty (pez ángel) y una mancha doble en Butter Hamlet (mero), y su posible significado genético

Three anomalies are described: a scythebill in Greater Antillean Grackle, Quiscalus niger (Boddaert) (Passeriformes: Emberizidae), a crown color pattern in Rock Beauty, Holacanthus tricolor (Bloch) (Perciformes: Pomacanthidae), and a double-spot color pattern in Butter Hamlet, Hypoplectrus unicolor (Walbaum) (Perciformes: Pomacanthidae). Bill anomalies are generally thought to be genetic in origin and genetic changes in bill shape can occur rapidly in a population. The scythebill anomally demonstrates how quickly a drastic bill modification may occur. The crown color pattern anomaly is similar to distinctive markings found in other members of this genus [Queen Angelfish, H. ciliaris (Linnaeus) and hybrid Townsend Angelfish H. ciliaris X H. bermudensis Goode] in the tropical western Atlantic. It suggests how quickly this pattern could have originated in the other species, and/or some propensity of this pattern in the genus. The distinct double-spot color pattern anomaly suggests how quickly new color patterns can originate in genus Hypoplectrus. This is important because species in this genus are distinguished almost solely on the basis of color pattern and speciation may be occurring rapidly. Anomalies should be recorded because they may give us some hints at the genetic origin of species characters and some could represent potentially inheritable characters. We suggest these potentially inheritable characters could be recognized and described when they first arise in an individual and before they become inherited by a population. Following these potentially inheritable characters could help to explain how such characters enter into a population. This approach to the study of inherited characters could fill a void in our knowledge of evolution and speciation. Rev. Biol. Trop. 54 (Suppl. 3): 161-169. Epub 2007 Jan. 15.

Se describen tres anomalías: el pico de guadaña en el chinchilín, Quiscalus niger (Boddaert) (Passeriformes: Emberizidae), un patrón de color de corona en el isabelita medioluto, Holacanthus tricolor (Bloch) (Perciformes: Pomacanthidae), y un patrón de color de doble mancha en el vaca blanca, Hypoplectrus unicolor (Walbaum) (Perciformes: Pomacanthidae). Generalmente se piensa que las anomalías en el pico son de origen genético y que los cambios genéticos en la forma del pico pueden ocurrir rápidamente en una población. La anomalía del pico de guadaña demuestra cuan rápido puede ocurrir una modificación drástica del pico. La anomalía del patrón de color de corona es similar a otras marcas distintivas encontradas en otros miembros de este género [isabelita reina, H. ciliaris (Linnaeus) y el híbrido isabelita azul H. ciliaris X H. bermudensis Goode] en el Atlántico occidental tropical y también indica cambios rápidos. Esto es importante porque las especies de este género se distinguen casi solamente por patrones de color. Las anomalías deberían ser registradas ya que podrían darnos algunas pistas acerca del origen genético de las características de las especies. Proponemos que los caracteres potencialmente heredables pueden reconocerse y describirse cuando aparecen en un individuo, antes de que sean heredados a la población, llenando un vacío en nuestro conocimiento de la evolución y la especiación.

Organochlorine contaminants and biomarker response in double-crested cormorants nesting in Green Bay and Lake Michigan, Wisconsin, USA.

Double-crested cormorant (Phalacrocorax auritus) eggs at pipping and sibling 10-day-old chicks were collected from two colonies in Green Bay, WI, one colony in Lake Michigan, WI, and reference colonies in South Dakota and Minnesota. Egg contents and chicks were analyzed for organochlorine contaminants including polychlorinated biphenyl (PCB) congeners. Livers of embryos and chicks were assayed for hepatic microsomal ethoxyresorufin-O-dealkylase (EROD) activity. Eggshell thickness and the physical dimensions of embryo brains were measured. Concentrations of organochlorines, including p,p'-DDE (p,p'-dichlorodiphenyldichloroethylene), PCBs, and PCB congeners were generally an order of magnitude higher in eggs and chicks from Wisconsin than from reference locations. Total PCBs averaged 10-13 microg/g wet weight in eggs from three Wisconsin colonies compared to 0.9 microg/g PCBs from reference locations. Double-crested cormorant chicks accumulated on average 33-66 microg PCBs/day and 7-12 microg p,p'-DDE/day in the Wisconsin colonies compared to 0 microg PCBs/day and 1 microg p,p'-DDE/day in the reference colonies. At pipping, EROD activity in the livers of cormorant embryos was significantly higher in the Wisconsin colonies and significantly correlated with PCBs and the toxic equivalents (TEQs) of aryl hydrocarbon-active PCB congeners relative to 2,3,7,8-tetrachlorodibenzo-p-dioxin. However, in 10-day-old chicks EROD activity was not consistently different among colonies and was not correlated with PCBs or TEQs. A significant negative relationship between embryo brain asymmetry and the size of the egg suggested that physical constraint might be an important factor influencing the response of this bioindicator. Thinner eggshells in two colonies located near Door County, Wisconsin, suggested that historic p,p'-DDE residues associated with orchards are still an important source of p,p'-DDE in the local environment.

Chlorinated hydrocarbons and biomarkers of exposure in wading birds and fish of the lower Rio Grande Valley, Texas.

During 1997 we evaluated reproductive success in colonial water birds nesting in the Lower Rio Grande Valley (LRGV), Texas, and correlated success with concentrations of contaminants in eggs. We also measured steroid hormones and gonadosomatic index (GSI) as biomarkers of endocrine effects in common carp (Cyprinus carpio). Nest and fledging success of green herons (Butorides virescens) and great egrets (Ardea alba) were similar to those found in other parts of North America; however, nesting success of black-crowned night-herons (Nycticorax nycticorax) was lower, very likely due to flooding of the nesting area. Except for DDE and toxaphene, all chlorinated pesticides in bird eggs were low and not of concern for negative effects on any of the three species. DDE was highest in green heron eggs and seemed to increase along a geographic gradient from west to east, with eggs from Falcon Reservoir containing low concentrations, and those at Los Indios containing the highest concentrations (approx. 11,000 ng/g WW), near or above the threshold for reproductive impairment. DDE levels in great egrets and black-crowned night-herons were below those that are associated with reproductive impairment. Mean DDE levels in carp at the JAS Farms site were above the threshold level suggested for predator protection. Toxaphene was detected in about 20% of the samples with high levels observed in green heron eggs from Los Indios (mean = 4,402 ng/g WW). These are the highest toxaphene levels reported in bird eggs in the LRGV. Toxaphene levels in fish ranged between 90 and 312 ng/g WW. In general, PCBs in bird eggs and fish tissue were low and at levels not of concern for reproductive effects. The greatest concentrations of testosterone and 11-ketotestosterone were detected in fish from the JAS Farms site, which also had the greatest concentrations of DDE. Increased androgen production and gonad development in fish at this site, relative to Pharr, could be possibly associated with endocrine disrupting effects of p,p'-DDE. DDE, toxaphene, PCBs, and hormones were highest in birds and fish from the eastern edge of the study area.

Factors on farms in eastern Australia associated with the development of tibiotarsal rotation in ostrich chicks.

OBJECTIVES: To determine the incidence of tibiotarsal rotation (TTR) in ostrich chicks and to identify factors on farms associated with the development of TTR. DESIGN: A cross-sectional study using a personal interview. PROCEDURE: During a single visit to 31 farms, data were collected about a defined cohort of chicks, and about farm-related factors that may be associated with the development of TTR. Farms were categorised for TTR status according to the proportion of the chick cohort that survived to 10 weeks of age without developing TTR. Chick performance was measured using descriptive epidemiological methods and univariable analyses were conducted to identify unconditional associations between TTR status and farm-related factors. RESULTS: Ninety-six of 931 ostrich chicks from 21 (68%) farms developed TTR during the first 10 weeks following hatch. Lower limb deformities were the most common cause of death in chicks between 3 and 10 weeks of age. On seven (23%) study farms, where less than 87% of young chicks survived to 10 weeks without developing this condition, TTR was considered a serious problem. Twelve farm-related factors were associated with farm TTR status, including eight chick-related variables (aspects of nutrition, pen design and management) and four farm-related variables (related to the number of veterinary visits, farm location, number of rainy days and the person most closely involved with chick raising. CONCLUSION: The results confirm a continuing problem of young chick wastage in eastern Australia. TTR was an important cause of mortality in farmed ostrich chicks during the first 10 weeks after hatch. The factors that producers could address to reduce the incidence of TTR include pen design, access to water and nutrition.

Multiple intussusceptions in a juvenile rhea (Rhea americana) with proventricular impaction.

Multiple intussusceptions of the small intestine were identified in a 4-mo-old rhea (Rhea americana) that died acutely after chronically poor growth. The chick was one of a group of 12 chicks that exhibited musculoskeletal deformities, poor growth, and subsequent death. Gross necropsy findings of this chick revealed proventricular impaction by sticks and stones accompanied by multiple intussusceptions of the small intestine. This finding identifies a disease process that may afflict ratites when raised for production and that may complicate treatment of proventricular impaction.

In ovo 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure in three avian species. 1. Effects on thyroid hormones and growth during the perinatal period.

Thyroid hormones are important in the perinatal growth and development of avian species, and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds have been shown to cause alterations in these hormones in laboratory animals. Since the decreased reproductive success in certain fish-eating bird populations exposed to TCDD and related compounds is characterized by high embryo and hatchling mortality, we examined the effects of in ovo TCDD exposure on plasma thyroid hormone concentrations (total T3, total T4) and body and skeletal growth during the perinatal period in the domestic chicken (Gallus gallus), domestic pigeon (Columba livia), and great blue heron (Ardea herodias). Hepatic ethoxyresorufin O-deethylase (EROD) activity was also determined as an enzymatic marker of cytochrome P450IA induction by TCDD. [3H]TCDD was injected into the air cell of chicken eggs (21-day incubation period) on Embryonic Day 4.5 (0.1 microgram/kg egg), pigeon eggs (18-day incubation period) on Embryonic Day 3.5 (1 microgram/kg egg) and Embryonic Day 14 (3 microgram/kg egg), and heron eggs (28-day incubation period) at approximately the midpoint of incubation (2 microgram/kg egg). Chickens were euthanized on Embryonic Days 17 and 19, day of hatch (Embryonic Day 21), and Days 2 and 4 after hatch. Pigeons and herons were euthanized either at hatch (Embryonic Days 18 and 28, respectively), or fed an uncontaminated diet for 7 days prior to sacrifice. Although hepatic EROD activity was induced 13- to 43-fold above controls in chickens, there was no effect of TCDD exposure on hatchability, body growth, subcutaneous edema, or plasma thyroid hormone levels. In pigeons exposed to TCDD on Embryonic Day 3.5, EROD was induced 6- to 15-fold, hatchability was decreased, liver to body weight ratio was elevated, and body and skeletal growth were decreased (p < 0.01); however, there was no effect of TCDD exposure on plasma thyroid hormone levels. Similarly, in pigeons exposed to TCDD on Embryonic Day 14, EROD was induced 10- to 14-fold, liver to body weight ratio was elevated, and body and skeletal growth were decreased (p < 0.01), but there was no effect of TCDD treatment on plasma thyroid hormone levels. In herons, hepatic EROD activity was induced 2- to 3-fold above control birds, similar to EROD activities measured in heron hatchlings exposed to environmental levels of TCDD and related chemicals in the Strait of Georgia, British Columbia. However, this level of TCDD exposure had no effect on plasma thyroid hormone levels or body growth in herons. Collectively, these results suggest that perinatal plasma thyroid hormone levels cannot be used as relatively noninvasive biomarkers of TCDD exposure during embryonic development in chickens, pigeons, and great blue herons.

In ovo 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure in three avian species. 2. Effects on estrogen receptor and plasma sex steroid hormones during the perinatal period.

As opposed to mammals, the heterogametic sex in birds is female, and sexual differentiation of the central nervous system away from the intrinsic male pattern is dependent on ovarian estrogen secretions during the perinatal period. The contamination of aquatic systems with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds has been suggested to be responsible for decreased reproductive success in certain wild fish-eating bird populations. Since TCDD has been shown to alter estrogenic status in laboratory animals, we determined the effects of in ovo TCDD exposure on hepatic estrogen receptor (ER) concentrations and affinities, and plasma estradiol concentrations during the perinatal period in the domestic chicken (Gallus gallus), domestic pigeon (Columba livia), and great blue heron (Ardea herodias). Plasma testosterone levels were also determined in herons as an indication of androgenic status. [3H]TCDD was injected into the air cell of chicken eggs on Embryonic Day 4.5 (0.1 microgram/kg egg), pigeon eggs on Embryonic Day 3.5 (1 microgram/kg egg) and Embryonic Day 14 (3 micrograms/kg egg), and heron eggs at approximately Embryonic Day 13 (2 micrograms/kg egg). Chickens were euthanized on Embryonic Days 17 and 19, hatch, and Days 2 and 4 after hatch. Pigeons and herons were either euthanized at hatch or fed an uncontaminated diet for 7 days prior to termination. Between 5 and 10% of the injected [3H]TCDD dose was measured in the liver of hatchlings. There was no effect of in ovo TCDD exposure on hepatic ER levels or plasma estradiol concentrations in female chickens and pigeons exposed early in incubation. In female pigeons exposed during the latter third part of incubation to a TCDD dose that would cause high embryo lethality if injected early in incubation, hepatic ER concentrations were elevated (p < 0.001) and plasma estradiol concentrations were decreased (p < 0.01) at hatch. There was no effect of TCDD exposure on plasma estradiol levels in male pigeons. In herons, TCDD exposure had no effect on hepatic ER levels or plasma estradiol and testosterone concentrations at either time point. We conclude that in chicken, pigeon, and great blue heron hatchlings exposed early in incubation to low doses of TCDD, hepatic ER levels and plasma estradiol concentrations are not biomarkers of toxicity.

Morphometric abnormalities in brains of great blue heron hatchlings exposed in the wild to PCDDs.

Great blue heron hatchlings from colonies in the Strait of Georgia, British Columbia, Canada are being monitored for environmental contaminant exposure and effects by the Canadian Wildlife Service. The contaminants of concern are polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), primarily derived from kraft pulp mill effluent. The levels of PCDDs and PCDFs in eggs from the most contaminated colonies peaked in 1988 and 1989 and dropped dramatically through 1990 to 1992. Brains of heron hatchlings (taken as eggs from the wild and hatched in the laboratory) were analyzed for gross morphological abnormalities. Brains from highly contaminated colonies (Crofton, British Columbia and University of British Columbia Endowment Lands) in 1988 exhibited a high frequency of intercerebral asymmetry. The frequency of this abnormality decreased in subsequent years as the levels of TCDD and TCDD-TEQs (toxic equivalence factors) decreased. The asymmetry was significantly correlated with the level of TCDD and TCDD-TEQs in eggs taken from the same nest. Yolk-free body weight negatively correlated and the brain somatic index positively correlated with the TCDD level in such pair-matched eggs. These results indicate that gross brain morphology, and specifically intercerebral asymmetry, may be useful as a biomarker for the developmental neurotoxic effects of PCDDs and related chemicals.

Serum- and bone-mineral status of ostriches with tibiotarsal rotation.

Tibiotarsal rotation in ostrich chicks is a serious problem that accounts for considerable financial loss to ostrich farmers. Serum- and bone-mineral analyses of 20 ostrich chicks with tibiotarsal rotation were compared with serum- and bone-mineral analyses of eight normal ostrich chicks of comparable age, sex and body mass, and raised under identical conditions. The serum-zinc values were significantly higher and the bone-calcium and phosphorus values significantly lower in the affected group than in the group of normal ostrich chicks. The results indicated poor mineralization of bone with subsequent reactive osteoid formation.

[Breed-dependent anomalies in ornamental birds]. / Zuchtbedingte Anomalien bei Ziervögeln.

Following a definition of the terms pet bird and domestication, and a description of important mechanisms which may have played a role during domestication, a short review is given on the various changes that occurred and have been used selectively by humans: changes in body size, skin and feathers, skull, metabolisms, and the central nervous system including behavior and disturbances of behavior. Implications for animal welfare are considered.

Biological effects of polychlorinated dibenzo-p-dioxins, dibenzofurans, and biphenyls in double-crested cormorant chicks (Phalacrocorax auritus).

The present project assessed the effect of environmental contamination with polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls (PCBs) on hepatic microsomal ethoxyresorufin O-deethylase (EROD) activities and morphological parameters in matched double-crested cormorant (Phalacrocorax auritus) hatchlings from egg clutches chosen for chemical analysis. Double-crested cormorant eggs were collected from five colonies across Canada, with differing levels of contamination. Levels of contamination expressed in sum of 2,3,7,8-tetrachlorodibenzo-p-dioxin-toxic equivalents (TCDD-toxic equivalents or TEQ, ng/kg egg; mean +/- SEM) were: Saskatchewan, 250 +/- 50; Chain Islands, 672 +/- 73; Christy Islet, 276 +/- 14; Crofton, 131, n = 1; and Lake Ontario, 1606 +/- 118. In the hatchlings, hepatic EROD activities (pmol/min/mg protein; mean +/- SEM) were: Saskatchewan, 283 +/- 42; Chain Islands, 516 +/- 98; Christy Islet, 564 +/- 91; Crofton, 391 +/- 52; and Lake Ontario, 2250 +/- 156. Hepatic microsomal EROD activity (pmol/min/mg protein) regressed positively on TEQ (r2 = .69; p < .00005; n = 25). Yolk weight (g) regressed negatively on TEQ (r2 = .44; p = .00005). Wing length (mm) regressed negatively on PCB-169 (r2 = .28; p = .007). Monospecific antibodies raised against rat cytochrome P-450 1A1 recognized a protein in the hepatic microsomes of the double-crested cormorant, and also in those of the great blue heron (Ardea herodias), using immunoblotting. The intensity of the stained band increased with increased EROD activity, supporting the assumption that ethoxyresorufin is a suitable substrate for avian cytochrome P-450 1A1. These results validate the use of avian hepatic microsomal EROD activity as an index of cytochrome P-450 1A1 induction by environmental levels of polychlorinated aromatic hydrocarbons and as a useful screening tool to determine the extent of exposure to such chemicals. Furthermore, the induction of cytochrome P-450 1A1 observed in the cormorant indicates that the Ah receptor-mediated process, by which TCDD and related chemicals exert many of their toxicities, has been activated.

The incidence of tibiotarsal rotation in the ostrich (Struthio camelus).

Abnormal lateral tibiotarsal rotation has been reported as one of many abnormalities affecting the pelvic appendicular skeleton of birds. In this study, lateral rotation of the tibiotarsus affected 89 out of 1,407 ostrich chicks between 2 weeks and 6 months of age raised at the Oudtshoorn Experimental Farm. There was no sexual preference, but the lesion affected the right pelvic limb almost exclusively and very rarely the left limb. Pelvic appendicular skeletal abnormalities make a significant contribution to mortalities in ostrich chicks.