Acute death of kangaroos in a zoo due to highly pathogenic Corynebacterium pseudotuberculosis and Yersinia pseudotuberculosis

Background: “Lumpy jaw” is disease effecting wallabies and kangaroos, particularly in Macropus rufus and Macropusgiganteus. In the most serious situations, additional tooth loss and fistulas follow, accompanied by a stench, weight loss,and eventually death due to sepsis or blood poisoning. “Lumpy jaw” disease has seriously affected the normal display andhealth of kangaroos, and cause a huge economic loss. There was an outbreak of jaw infection in kangaroos at the HongshanForest Zoo. Two Macropus giganteus and two Macropus rufus died of “lumpy jaw”. The main objective of the describingcase was to isolate pathogens, provide a basis for follow-up treatment, and serve to establish a disease prevention protocol.Case: Four grown-up kangaroos (two Macropus giganteus and two Macropus rufus) were raised in Hongshan Forest Zoo,which had obviously clinical symptoms, such as oral lesions of pus, necrotic tissue, rotting teeth, then died of “lumpyjaw”. Oral swab samples were collected from the lesion sites of the dying kangaroos. Mice experiments were conducted toexamine the pathogenicity of the strains. Tests of antimicrobial susceptibity were performed to prescribe with better drugtreatments for kangaroos. Corynebacterium pseudotuberculosis and Yersinia pseudotuberculosis were identified based onmorphology, culture characteristics and biochemical tests. Corynebacterium pseudotuberculosis (G+) in Sucrose, Mannitol,Lactose, Maltose, Glucose tubes were positive, that acids and gases both production, in Gelatin liquefaction, Indol test,MR were positive, that only acids production, others were negative; Yersinia pseudotuberculosis (G-) in Urea, MR werepositive, that only acids production, others were negative.The infected mice presented with gum erosion or ulcers whenthe two pathogens were injected subcutaneous at the oral regional by 2-3 point at 0.2 mL of individual strains 1.0×109CFU/mouse...(AU)

The tammar wallaby: a non-traditional animal model to study growth axis maturation.

Maturation of the growth hormone (GH)/insulin-like growth factor 1 (IGF1) axis is a critical developmental event that becomes functional over the peripartum period in precocial eutherian mammals such as sheep. In mice and marsupials that give birth to altricial young, the GH/IGF1 axis matures well after birth, suggesting that functional maturation is associated with developmental stage, not parturition. Recent foster-forward studies in one marsupial, the tammar wallaby (Macropus eugenii), have corroborated this hypothesis. 'Fostering' tammar young not only markedly accelerates their development and growth rates, but also affects the timing of maturation of the growth axis compared with normal growing young, providing a novel non-traditional animal model for nutritional manipulation. This review discusses how nutrition affects the maturation of the growth axis in marsupials compared with traditional eutherian animal models.

Acute death of kangaroos in a zoo due to highly pathogenic Corynebacterium pseudotuberculosis and Yersinia pseudotuberculosis

Background: “Lumpy jaw” is disease effecting wallabies and kangaroos, particularly in Macropus rufus and Macropusgiganteus. In the most serious situations, additional tooth loss and fistulas follow, accompanied by a stench, weight loss,and eventually death due to sepsis or blood poisoning. “Lumpy jaw” disease has seriously affected the normal display andhealth of kangaroos, and cause a huge economic loss. There was an outbreak of jaw infection in kangaroos at the HongshanForest Zoo. Two Macropus giganteus and two Macropus rufus died of “lumpy jaw”. The main objective of the describingcase was to isolate pathogens, provide a basis for follow-up treatment, and serve to establish a disease prevention protocol.Case: Four grown-up kangaroos (two Macropus giganteus and two Macropus rufus) were raised in Hongshan Forest Zoo,which had obviously clinical symptoms, such as oral lesions of pus, necrotic tissue, rotting teeth, then died of “lumpyjaw”. Oral swab samples were collected from the lesion sites of the dying kangaroos. Mice experiments were conducted toexamine the pathogenicity of the strains. Tests of antimicrobial susceptibity were performed to prescribe with better drugtreatments for kangaroos. Corynebacterium pseudotuberculosis and Yersinia pseudotuberculosis were identified based onmorphology, culture characteristics and biochemical tests. Corynebacterium pseudotuberculosis (G+) in Sucrose, Mannitol,Lactose, Maltose, Glucose tubes were positive, that acids and gases both production, in Gelatin liquefaction, Indol test,MR were positive, that only acids production, others were negative; Yersinia pseudotuberculosis (G-) in Urea, MR werepositive, that only acids production, others were negative.The infected mice presented with gum erosion or ulcers whenthe two pathogens were injected subcutaneous at the oral regional by 2-3 point at 0.2 mL of individual strains 1.0×109CFU/mouse...

Infection with Toxoplasma gondii in a red kangaroo (Macropus rufus) and a Patagonian mara (Dolichotis patagonum) in captivity.

Toxoplasmosis is an infectious, zoonotic and parasitic disease, caused by Toxoplasma gondii. In this manucript, two cases of infection with T. gondii in captive animals from a zoological park in the central region of Chile are described. One case was a red kangaroo (Macropus rufus), which is highly susceptible to the infection, and the other was a Patagonian mara (Dolichotis patagonum), a rodent in which there is no previous report of the infection. Both animals had myocarditis, with the presence of intralesional tachizoites and cysts suggestive of infection with T. gondii. This infection was confirmed by immunohistochemistry in both animals. The origin of the infection is unknown, but it is likely that free ranging domestic felines were associated with the dissemination of the parasites. This highlights the importance of controlling the domestic animal populations in zoological parks. To the best of our knowledge, this is the first time that T. gondii infection is described in a Patagonian mara, adding a new host for this infectious agent.

Infection with Toxoplasma gondii in a red kangaroo (Macropus rufus) and a Patagonian mara (Dolichotis patagonum) in captivity / Infecção por Toxoplasma gondii em um canguru vermelho (Macropus rufus) e em uma mara (Dolichotis patagonum) em cativeiro

Abstract Toxoplasmosis is an infectious, zoonotic and parasitic disease, caused by Toxoplasma gondii. In this manucript, two cases of infection with T. gondii in captive animals from a zoological park in the central region of Chile are described. One case was a red kangaroo (Macropus rufus), which is highly susceptible to the infection, and the other was a Patagonian mara (Dolichotis patagonum), a rodent in which there is no previous report of the infection. Both animals had myocarditis, with the presence of intralesional tachizoites and cysts suggestive of infection with T. gondii. This infection was confirmed by immunohistochemistry in both animals. The origin of the infection is unknown, but it is likely that free ranging domestic felines were associated with the dissemination of the parasites. This highlights the importance of controlling the domestic animal populations in zoological parks. To the best of our knowledge, this is the first time that T. gondii infection is described in a Patagonian mara, adding a new host for this infectious agent.(AU)

Resumo Toxoplasmose é uma doença parasitária infecciosa e zoonótica causada por Toxoplasma gondii. São descritos dois animais com toxoplasmose, mantidos em cativeiro, em um zoológico na região central do Chile. Um destes foi um canguru vermelho (Macropus rufus), o qual é altamente suscetível à infecção; o outro foi uma mara (Dolichotis patagonum), um roedor sem relato prévio de infecção por T. gondii. Ambos os animais tinham miocardite associada a organismos protozoários intralesionais, sugestivos de infecção por Toxoplasma gondii. Esta infecção foi confirmada pela imuno-histoquímica, nos dois animais. A origem da infecção é desconhecida, mas é provável que felinos domésticos errantes estejam associados com a disseminação do protozoário. Isso destaca a importância do controle populacional de animais domésticos em zoológicos. Até onde se sabe, esta é a primeira vez que a infecção por T. gondii é descrita em uma mara, adicionando um novo hospedeiro para este agente infeccioso.(AU)

Infection with Toxoplasma gondii in a red kangaroo (Macropus rufus) and a Patagonian mara (Dolichotis patagonum) in captivity / Infecção por Toxoplasma gondii em um canguru vermelho (Macropus rufus) e em uma mara (Dolichotis patagonum) em cativeiro

Abstract Toxoplasmosis is an infectious, zoonotic and parasitic disease, caused by Toxoplasma gondii. In this manucript, two cases of infection with T. gondii in captive animals from a zoological park in the central region of Chile are described. One case was a red kangaroo (Macropus rufus), which is highly susceptible to the infection, and the other was a Patagonian mara (Dolichotis patagonum), a rodent in which there is no previous report of the infection. Both animals had myocarditis, with the presence of intralesional tachizoites and cysts suggestive of infection with T. gondii. This infection was confirmed by immunohistochemistry in both animals. The origin of the infection is unknown, but it is likely that free ranging domestic felines were associated with the dissemination of the parasites. This highlights the importance of controlling the domestic animal populations in zoological parks. To the best of our knowledge, this is the first time that T. gondii infection is described in a Patagonian mara, adding a new host for this infectious agent.

Resumo Toxoplasmose é uma doença parasitária infecciosa e zoonótica causada por Toxoplasma gondii. São descritos dois animais com toxoplasmose, mantidos em cativeiro, em um zoológico na região central do Chile. Um destes foi um canguru vermelho (Macropus rufus), o qual é altamente suscetível à infecção; o outro foi uma mara (Dolichotis patagonum), um roedor sem relato prévio de infecção por T. gondii. Ambos os animais tinham miocardite associada a organismos protozoários intralesionais, sugestivos de infecção por Toxoplasma gondii. Esta infecção foi confirmada pela imuno-histoquímica, nos dois animais. A origem da infecção é desconhecida, mas é provável que felinos domésticos errantes estejam associados com a disseminação do protozoário. Isso destaca a importância do controle populacional de animais domésticos em zoológicos. Até onde se sabe, esta é a primeira vez que a infecção por T. gondii é descrita em uma mara, adicionando um novo hospedeiro para este agente infeccioso.

Toxoplasmosis sistémica en un canguro rojo (Macropus rufus) cautivo / Systemic toxoplamosis in a captive red kangaroo (Macropus rufus)

Los objetivos del estudio fueron presentar y documentar los hallazgos histopatológicos de toxoplasmosis sistémica en un canguro rojo (Macropus rufus) mantenido en cautiverio donde se describen los hallazgos macro y microscópicos encontrados y los análisis adicionales realizados. En el laboratorio de histopatología animal (Universidad de los Llanos) se recibieron muestras de tejidos fijados en formol tamponado, al 10% que procedían de un ejemplar macho de Macropus rufus, de ocho años de edad y 50 kg de peso corporal. Las muestras se procesaron mediante métodos rutinarios para microscopía óptica. Los cortes histológicos de 3-4 mm de grosor se colorearon con Hematoxilina-Eosina (H&E) y se realizó en algunos cortes la tinción de Ácido Periódico Schiff (PAS), PCR e IHQ. Al análisis histopatológico se encontró una toxoplasmosis sistémica asociada a quistes de protozoarios con inmunoreactividad positiva para T. gondii. La detección de T gondii en tejidos en formalina fue hecha usando dos ensayos de PCR que señalaban segmentos de ADN de diferentes secuencias repetitivas encontradas en T gondii y la IHQ confirmo lo hallado por PCR. Histopatológicamente se diagnosticó infección crónica por protozoarios eucoccideos de la familia Sarcocystidae. El diagnóstico etiológico fue de toxoplasmosis.

The objetives of this study were to present and document the hystopathologycal findings of systemic toxoplamosis in a captive red kangaroo (Macropus rufus) which described macro and microscopic findings of the hystopathological analysis. In the laboratory of animal histopathology (Universidad de los Llanos) formalin fixed tissue specimens were received, from a captive male Macropus rufus, who was eight years old and weighed 50 kg. The samples were processed by usual methods for optical microscopy. The histological sections of 3-4 mm thick were colored with Hematoxilin-Eosin (H&E) and then some samples stained with Periodic Acid Schiff (PAS), and processed by PCR and IHQ. Once the histopathological analysis was performed systemic toxoplasmosis was associated to protozoa cysts immunoreactives to T. gondii. The molecular detection of T. gondii in formalin fixed tissues was made using two PCR tests and confirmated by IHQ. Histopathologically a chronic infection by an eucoccideo protozoa from the Sarcocystidae family was diagnosed. The etiologic diagnosis was toxoplasmosis.

How does a hopping kangaroo breathe?

We developed a model to demonstrate how a hopping kangaroo breathes. Interestingly, a kangaroo uses less energy to breathe while hopping than while standing still. This occurs, in part, because rather than using muscle power to move air into and out of the lungs, air is pulled into (inspiration) and pushed out of (expiration) the lungs as the abdominal organs "flop" within the kangaroo's body. Specifically, as the kangaroo hops upward, the abdominal organs lag behind, and the insertion of the diaphragm is pulled toward its origin, flattening the dome and increasing the vertical dimension of the thoracic cavity (the thoracic cavity and lungs enlarge). Increasing the volume of the thoracic cavity reduces alveolar pressure below atmospheric pressure (barometric pressure), and air moves into the alveoli by bulk flow. In contrast, the impact of the organs against the diaphragm at each landing causes expiration. Specifically, upon landing, the abdominal organs flop into the diaphragm, causing it to return to its dome shape and decreasing the vertical dimension of the thoracic cavity. This compresses the alveolar gas volume and elevates alveolar pressure above barometric pressure, so air is expelled. To demonstrate this phenomenon, the plunger of a syringe model of the respiratory system was inserted through a compression spring. Holding the syringe and pressing the plunger firmly against a hard surface expels air from the lungs (the balloon within the syringe deflates) and compresses the spring. This models the kangaroo landing after a hop forward. Subsequently, the compression spring provides the energy for the "kangaroo" to "hop" forward upon the release of the syringe, and air enters the lungs (the balloon within the syringe inflates). The model accurately reflects how a hopping kangaroo breathes. A model was chosen to demonstrate this phenomenon because models engage and inspire students as well as significantly enhance student understanding.

Toxoplasmosis and genotyping of Toxoplasma gondii in Macropus rufus and Macropus giganteus in Argentina.

Toxoplasma gondii infection is frequently asymptomatic; however, it can be severe or even fatal to some hosts. In this study, diagnosis of disseminated toxoplasmosis in one red kangaroo (Macropus rufus) and one great grey kangaroo (Macropus giganteus) from the La Plata Zoo, Argentina and the isolation and molecular characterization of T. gondii are reported. Both male kangaroos showed depression and sudden death. Toxoplasma gondii infection was diagnosed by fresh examination, histopathology, immunohistochemistry, PCR and bioassay in mice. During fresh examination many protozoan cysts were observed in diaphragm, heart and hind limb muscles of M. rufus. Cysts were also observed in samples from M. giganteus, although in lower number. Cysts from both kangaroos stained strongly with T. gondii anti-serum by immunohistochemistry. The M. rufus showed more considerable histopathological lesions like non-suppurative meningoencephalitis, myositis and myocarditis. All mice inoculated with tissues from both kangaroos developed IFAT titers to T. gondii (titer >or=800) and brain cysts at necropsy. Both T. gondii isolates were maintained by mice passages and the M. rufus isolate was also maintained in cell culture. Toxoplasma gondii DNA from tissue samples was analyzed by PCR-RFLP analysis using the markers 5'SAG2, 3'SAG2, BTUB, GRA6, SAG3, c22-8, L358, PK1, c29-2 and Apico. Genotyping revealed that the T. gondii isolate from M. rufus was clonal type III and the isolate from M. giganteus was clonal type II. This is the first report of disseminated toxoplasmosis in M. rufus and M. giganteus in Argentina caused by genotypes of T. gondii considered non-virulent in a mouse model.

Gross anatomy of the heart in the western grey kangaroo (Macropus fuliginosus) / Anatomía macroscópica del corazón en el canguro gris occidental (Macropus fuliginosus)

The aim of this study was provide a description of the macroscopic heart anatomy of the kangaroo Macropus fuliginosus. The terms of the Nomina Anatomica Veterinaria were employed. Heart did not have interventricular sulcus. Auricles were located in both faces of the heart. Right ventricle had slight septomarginal trabecula that extended between papilar muscles and the parietal wall. Right ventricle parietal wall had plenty of trabecula carneae. Septal wall was smooth and had three papilar muscles. Papilar muscles of left ventricle were two and they were located over parietal wall. Septal walls and parietal of left ventricle were full of trabecula carneae that surrounded papilar muscles. Two vessels derived from the aorta, right and left sinus coronary arteries and a septal artery. Septal artery gave irrigation to interventricular septum and derived from left sinus of the aorta and their lumen had a higher diameter than the left coronary artery. Coronary arteries had intra myocardic route.

El objetivo de este estudio fue proporcionar una descripción de la anatomía macroscópica de corazón el canguro Macropus fuliginosus. Fueron empleados los términos de la Nomina Anatómica Veterinaria. El corazón no tuvo surco interventricular. Las aurículas se encontraban en ambas caras del corazón. El ventrículo derecho presentó una trabécula septomarginal delgada que se extendía entre los músculos de la pared papilar y parietal. La pared parietal del ventrículo derecho presentó un montón de trabéculas carnosas. La pared septal era lisa y tenía tres músculos papilares. Los músculos papilares del ventrículo izquierdo fueron dos y se encontraron en la pared parietal. Las paredes septal y parietal del ventrículo izquierdo estaban llenas de trabéculas carnosas que rodeaban los músculos papilares. Dos vasos procedentes desde la aorta, arterias del seno coronario derecho e izquierdo, y la arteria septal. La arteria septal dio irrigación al septo interventricular y derivada desde el seno izquierdo de la aorta y su lumen tuvo un mayor diámetro que la arteria coronaria izquierda. Las arterias coronarias presentaron un trayecto intramiocardico.

Toxoplasmosis in captive Bennett's wallabies (Macropus rufogriseus) in Argentina.

Wallabies and other Australian marsupials are among the most susceptible species to Toxoplasma gondii. Fatal generalized toxoplasmosis was diagnosed in two captive 3 year-old female Bennett's wallabies (Macropus rufogriseus) from Argentina (w 1 and w 2) with a history of sudden death. Both animals had internal joeys which died 2 days after their mothers. Serologically, both females and one adult male without clinical signs from the same enclosure (w 3) had antibody titers for T. gondii>or=800 by the modified agglutination test (MAT); another adult male (w 4) was negative (MAT titer<25). Microscopically, tachyzoites were observed associated to non-suppurative meningoencephalitis, hepatitis, myositis, myocarditis and severe enteritis in hematoxylin and eosin stained sections from both w 1 and w 2. Immunohistochemically, parasites in heart, brain and liver sections of both female wallabies reacted with T. gondii antiserum. T. gondii was isolated from brain tissues of w 1 and w 2 by bioassay in mice and by culture in bovine monocytes and both isolates were cryopreserved. Genomic DNA was isolated from tachyzoites grown in cultures derived from both animals. The primer pair B22/B23 specific for T. gondii produced 115bp amplicons on poliacrylamide electrophoretic gels. Stray cats were suspected as the possible source of infection. Not all infected macropods were ill, showing that the infection may be asymptomatic and is not always fatal. A vertical infection could not be proved in the joey from w 2. As far as we know, this is the first confirmed report of toxoplasmosis in Bennet's wallabies in Argentina.

Photorepair prevents ultraviolet-induced apoptosis in human cells expressing the marsupial photolyase gene.

Photolyase absorbs blue light and employs the energy to remove UV-induced DNA damage, cyclobutane pyrimidine dimers, or pyrimidine pyrimidone (6-4) lesions. These enzymes have been found in many living organisms ranging from bacteria to aplacental mammals, but their photoreactivation effect, such as survival increase of UV-irradiated cells by light-illumination, has not been identified in placental mammals, including humans. Therefore, we introduced a photolyase gene derived from the marsupial rat kangaroo, Potorous tridactylus, into HeLa cells and established the first human cell line capable of photorepairing UV-induced pyrimidine dimers. Several clones were found to increase cell survival after UV irradiation when illuminated by fluorescent light. The induction of apoptosis by UV irradiation was investigated in these photoreactivation-proficient cells. Several typical features of the programmed cell death, such as internucleosomal DNA degradation, presence of subdiploid cells, loss of membrane integrity, and chromosomal condensation, were found to be induced by UV in the HeLa cells, but they can be reduced by photorepair. This implicates that cyclobutane pyrimidine dimers cause UV-induced apoptosis in human cells.

"Rodent-like" and "primate-like" types of astroglial architecture in the adult cerebral cortex of mammals: a comparative study.

Previous observations disclosed that astroglia with interlaminar processes were present in the cerebral cortex of adult New and Old World monkeys, but not in the rat, and scarcely in the prosimian Microcebus murinus. The present report is a more systematic and comprehensive comparative analysis of the occurrence of such processes in the cerebral cortex of several mammalian species. Brain samples were obtained from adult individuals from the following orders: Carnivora (canine), Rodentia (rat and mouse), Marsupialia (Macropus eugenii), Artiodactyl (bovine and ovine), Scandentia (Tupaia glis), Chiroptera (Cynopteris horsfieldii and C. brachyotis), and Primate: Prosimian (Eulemur fulvus), non-human primate species (Cebus apella, Saimiri boliviensis, Callithrix, Macaca mulatta, Papio hamadryas, Macaca fascicularis, Cercopithecus campbelli and C. ascanius) and from a human autopsy. Tissues were processed for immunocytochemistry using several antibodies directed against glial fibrillary acidic protein (GFAP), with or without additional procedures aimed at the retrieval of antigens and enhancement of their immunocytochemical expression. The cerebral cortex of non-primate species had an almost exclusive layout of stellate astrocytes, with only the occasional presence of long GFAP-IR processes in the dog that barely crossed the extent of lamina I, which in this species had comparatively increased thickness. Species of Insectivora and Chiroptera showed presence of astrocytes with long processes limited to the ventral basal cortex. Interlaminar GFAP-IR processes were absent in Eulemur fulvus, at variance with their limited presence and large within- and inter-individual variability as reported previously in Microcebus murinus. In New World monkeys such processes were absent in Callithrix samples, at variance with Cebus apella and Saimirí boliviensis. Overall, the expression of GFAP-IR interlaminar processes followed a progressive pattern: bulk of non-primate species (lack of interlaminar processes)--Chiroptera and Insectivora (processes restricted to allocortex) < strepsirhini < haplorhini (platirrhini < catarrhini). This trend is suggestive of the emergence of new evolutionary traits in the organization of the cerebral cortex, namely, the emergence of GFAP-IR long, interlaminar processes in the primate brain. Interlaminar processes may participate in a spatially restricted astroglial role, as compared to the one provided by the astroglial syncytium. It is proposed that the widely accepted concept of an exclusively astroglial syncytium is probably linked with a specific laboratory animal species ("rodent-type" or, rather, "general mammalian-type" model) that misrepresents the astroglial architecture present in the cerebral cortex of most anthropoid adult primates ("primate-type" model), including man.

Vaccination trials in Australia and Argentina confirm the effectiveness of the EG95 hydatid vaccine in sheep.

Experimental vaccine trials against hydatid disease have been undertaken in sheep using the EG95 recombinant vaccine. Challenge infection was with viable Echinococcus granulosus eggs obtained from a New Zealand isolate (dog/sheep cycle), an Australian isolate (dingo/wallaby cycle) and an Argentine isolate (dog/sheep cycle). Vaccination with EG95 conferred a high degree of protection against challenge with all three parasite isolates (protection range 96-100%). Taken together, the trials demonstrated that 86% of vaccinated sheep were completely free of viable hydatid cysts when examined approximately 1 year after challenge infection. Vaccination reduced the number of viable cysts by 99.3% compared with unvaccinated controls. These results suggest that the EG95 vaccine could have wide applicability as a new tool for use in hydatid control campaigns.

Human Bcl-2 expression delays ultraviolet-induced apoptosis in marsupial cells.

We have introduced the human bcl-2 gene under the control of the human metallothionein MTIIA promoter into the rat kangaroo PtK2 cell line. Two independent clones were obtained in which the levels of Bcl-2 protein expression can be controlled by the addition of metals in the culture medium. These cell lines were employed to investigate the effects of this protein in UV-induced apoptosis. Overexpression of Bcl-2 in PtK2 cells resulted in a delay in the appearance of apoptosis markers, such as chromatin condensation and internucleosomal DNA fragmentation. However, colony survival after UV was not affected, suggesting that Bcl-2 did not impose a definitive block for cell death. The elimination of cyclobutane pyrimidine dimers through photoreactivation 24 h after irradiation in cells overexpressing Bcl-2 did not affect apoptosis. This indicates that irreversible events in the signaling pathway of apoptosis occur in the period between irradiation and photoreactivation even in the presence of high levels of Bcl-2 protein can delay the onset of UV-induced apoptosis in these marsupial cells, early events triggered by the pyrimidine dimers, upstream from the Bcl-2 action, lead the cell to a state committed to die.

Ultraviolet-induced cell death is independent of DNA replication in rat kangaroo cells.

Rat kangaroo (Potorous tridactylus) cells have an efficient repair system for photoreactivation of lethal lesions induced by 254 nm UV. However, this ability is lost with increasing time after UV, being completely ineffective after 24 h. Critical events leading to UV-induced cell death must occur within this period of time. DNA synthesis was inhibited by the DNA polymerase inhibitor aphidicolin and the loss of the capability to photorepair lethal lesions was maintained as for replicating cells. Similar data were obtained in synchronized cells UV irradiated immediately before S phase. Under the same conditions, the ability to remove cyclobutane pyrimidine dimers by photoreactivation in these cells remained unchanged 24 h after irradiation. These data indicate that the critical events responsible for UV-induced cell death occur in the absence of DNA replication.

Sites of attachment in Amblyomma triguttatum triguttatum Koch (Acari: Ixodidae) on natural hosts.

The sites of attachment of Amblyomma triguttatum truguttatum were studied from June to September 1981 on 146 feral pigs (Sus scrofa) and from March to August 1982 and January 1983 on 68 grey kangaroos (Macropus giganteus), naturally infested. Two hundred fifty hour (81%) of 314 nymphs were detected on the ears of the pigs; neither adults nor larvae of A. t. triguttatum were found on S. scrofa. Six hundred ninety four (97%) of 715 larvae; 283 (96%) of 295 nymphs and 11 (79%) of 14 adults of A. t. triguttatum were found on the ears of the kangaroos. The proportion of the larvae and nymphs on the ears of kangaroos and pigs respectively, decreased with the increase of tick load.

Pineal and melatonin actions in reproductive endocrinology.

Daylength is the major environmental variable governing seasonal breeding, and the pineal gland is needed for this response to occur in many photosensitive species. Although dependent upon the integrity of its peripheral sympathetic innervation, the pineal has no efferent projections, and therefore it affects neuroendocrine function by humoral means. Melatonin has been proposed as the pineal hormone; its timed administration replicate the effect of daylength on seasonal breeding in several mammals, including long-day, like the hamster, and short-day breeders, like the sheep. The pineal is regulated primarily by photo-periodic information attaining the gland through a polysynaptic pathway initiated in the retinohypothalamic tract. Secondary regulators of pineal secretory activity are several steroid and polypeptide hormones. Melatonin synthesis is maximal during nighttime while during daylight it is suppressed. Melatonin acts on specific receptor sites at hypothalamic and perhaps extrahypothalamic sites to affect LHRH release. Changes in calcium fluxes, cyclic nucleotide and prostaglandin synthesis may underlie the neuroendocrine activity of melatonin at hypothalamic sites.