Comparative Aspects of the Endotoxin- and Cytokine-Induced Endocrine Cascade Influencing Neuroendocrine Control of Growth and Reproduction in Farm Animals

Disease in animals is a well-known inhibitor of growth and reproduction. Earlier studies were initiated to determine the effects of endotoxin on pituitary hormone secretion. These studies found that in sheep, growth hormone (GH) concentration was elevated, whereas insulin-like growth factor-I (IGF-I) was inhibited, as was luteinizing hormone (LH). Examination of the site of action of endotoxin in sheep determined that somatotropes expressed the endotoxin receptor (CD14) and that both endotoxin and interleukin-Iβ activated GH secretion directly from the pituitary. In the face of elevated GH, there is a reduction of IGF-I in all species examined. As GH cannot activate IGF-I release during disease, there appears to be a downregulation of GH signalling at the liver, perhaps related to altered nitration of Janus kinase (JAK). In contrast to GH downregulation, LH release is inhibited at the level of the hypothalamus. New insights have been gained in determining the mechanisms by which disease perturbs growth and reproduction, particularly with regard to nitration of critical control pathways, with this perhaps serving as a novel mechanism central to lipopolysaccharide suppression of all signalling pathways. This pathway-based analysis is critical to the developing novel strategies to reverse the detrimental effect of disease on animal production.     

Epidemic of blindness in kangaroos - evidence of a viral aetiology

OBJECTIVE: To determine the cause of an epidemic of blindness in kangaroos. DESIGN AND PROCEDURES: Laboratory examinations were made of eyes and brains of a large number of kangaroos using serological, virological, histopathological, electron microscopical, immunohistochemical methods, and PCR with cDNA sequencing. In addition, potential insect viral vectors identified during the disease outbreak were examined for specific viral genomic sequences. SAMPLE POPULATION: For histopathological analysis, 55 apparently blind and 18 apparently normal wild kangaroos and wallabies were obtained from New South Wales, Victoria, South Australia, and Western Australia. A total of 437 wild kangaroos and wallabies (including 23 animals with apparent blindness) were examined serologically. RESULTS: Orbiviruses of the Wallal and Warrego serogroups were isolated from kangaroos affected with blindness in a major epidemic in south-eastern Australia in 1994 and 1995 and extending to Western Australia in 1995/96. Histopathological examinations showed severe degeneration and inflammation in the eyes, and mild inflammation in the brains. In affected retinas, Wallal virus antigen was detected by immunohistochemical analysis and orbiviruses were seen in electron microscopy. There was serological variation in the newly isolated Wallal virus from archival Wallal virus that had been isolated in northern Australia. There were also variations of up to 20% in genotype sequence from the reference archival virus. Polymerase chain reactions showed that Wallal virus was present during the epidemic in three species of midges, Culicoides austropalpalis, C dycei and C marksi. Wallal virus nucleic acid was also detected by PCR in a paraffin-embedded retina taken from a blind kangaroo in 1975. CONCLUSION: Wallal virus and perhaps also Warrego virus are the cause of the outbreak of blindness in kangaroos. Other viruses may also be involved, but the evidence in this paper indicates a variant of Wallal virus, an orbivirus transmitted by midges, has the strongest aetiological association, and immunohistochemical analysis implicates it as the most damaging factor in the affected eyes.     

Foraging under uniform risk from different types of predators

Background  

Many animals live in environments where different types of predators pose a permanent threat and call for predator specific strategies. When foraging, animals have to balance the competing needs of food and safety in order to survive. While animals sometimes can choose between microhabitats that differ in their risk of predation, many habitats are uniform in their risk distribution. So far, little is known about adaptive antipredator behavior under uniform risk. We simulated two predator types, avian and mammalian, each representing a spatially uniform risk in the artificial resource landscapes. Voles served as experimental foragers.     

Interaction of Moniliophthora perniciosa biotypes with Micro‐Tom tomato: a model system to investigate the witches' broom disease of Theobroma cacao

The miniature tomato (Solanum lycopersicum) cultivar Micro‐Tom (MT) has become an important platform to investigate plant–pathogen interactions. In the case of the witches' broom disease of Theobroma cacao (cacao), the existence of Moniliophthora perniciosa isolates pathogenic to Solanaceae (S‐biotype) may enable the use of MT to circumvent limitations of the cacao host, whereas the availability of a non‐infective cacao C‐biotype allows the evaluation of contrasting responses of MT. Infection of MT by the S‐biotype led to stem swelling and axillary shoot growth to form broom‐like symptoms similar to the biotrophic phase in cacao, but the infected tissues did not progress to necrosis. Conversely, inoculation with the C‐biotype did not cause typical symptoms, but reduced plant height, appearing as a non‐host interaction. Histopathological characterization of the S‐biotype infection of MT by light and electron microscopy indicated limited germ tube penetration, preferentially through wounds at the base of trichomes or actively through the epidermis. No intracellular mycelium was observed, corroborating the lack of the necrotrophic stage of the pathogen. The analysis of gene expression during the interaction between the S‐ or C‐biotype with MT indicated that expression of plant defence‐associated genes differs for kinetics and intensity between a compatible or incompatible M. perniciosa–MT interaction. The pattern of spore germination and low rate of mycelia penetration suggests that the S‐biotype is not a fully adapted tomato pathogen, but possibly a case of broken non‐host resistance, and evidence suggests the occurrence of a non‐host MT response against the C‐biotype.     

Establishing the optimum dietary essential amino acid pattern for silvery‐black porgy (Sparidentex hasta) juveniles by deletion method

A 6‐week feeding trial was conducted to estimate the optimum dietary essential amino acid (EAA) pattern for silvery‐black porgy juvenile based on the AA deletion method. Eleven isonitrogenous and isoenergetic diets were formulated containing 60% of fish meal nitrogen and 40% of crystalline AA nitrogen. In the control diet, the EAA profile was made similar to fish meal protein. Ten other diets were formulated similar to the control diet but replacing 40% of each EAA by a mixture of non‐essential amino acids. Triplicate groups of fish (initial body weight of 4.7 g) were handfed with the experimental diets, three times a day, to visual satiation, for 42 days. At the end of the trial, final body weight of all EAA‐deficient groups was lower than that of control group, ranging from 6.3% of reduction with arginine‐deficient diet to 39.4% of reduction with lysine‐deficient diet, relatively to the control group. Based on the relationship between nitrogen retention and EAA intake of the control and EAA‐deficient diets, the optimal dietary EAA profile for silvery‐black porgy juveniles was estimated to be (g 16/g N): arginine 5.3, lysine 6.0, threonine 5.2, histidine 2.5, isoleucine 4.6, leucine 5.4, methionine + cysteine 4.0 (in a diet containing 0.6 cysteine), phenylalanine + tyrosine 5.6 (in a diet containing 1.9 tyrosine), tryptophan 1.0 and valine 4.6.     

Vertebrate population responses to reduced-impact logging in a neotropical forest

Vertebrate population densities were quantified in lowland central Guyana using line-transect censuses at three forest sites subjected to reduced-impact logging (RIL), and three adjacent unlogged sites. We censused a range of forest vertebrate species including large canopy-dwelling and terrestrial birds, three primates, one rodent and one tortoise. Two 4 km transects at each site were repeatedly surveyed during the wet season of 2008 to derive population density estimates on the basis of a cumulative survey effort of 416 km. RIL had ended within 16 months, and sites had been subjected to a mean extraction rate of 3.9 m³ ha⁻¹, equivalent to only 1.1 trees ha⁻¹. Three of the 15 vertebrate species examined here exhibited significantly different abundances at forest RIL sites, two of which were negative. Large frugivores such as primates were less abundant in sites subject to RIL, whereas smaller frugivores, granivores, folivores and insectivores were more common in logged sites. We are unable to reliably distinguish between responses of different taxonomic groups, since robust abundance metrics could only be estimated for four mammal species. Despite this, species traits including dietary guild, body mass, home range size and vertical stratification of forest use are used to explain varying responses. Our findings suggest that responsible reduced-impact logging practices in neotropical forests can be considered as a relatively benign form of forest management that can coexist with the requirements of both local economies and biodiversity conservation. However, our study sites experienced comparably low extraction rates, and detrimental effects such as hunting were low. Our results therefore provide an opportunity to scrutinise the effects of best practice logging systems, though do not necessarily represent typical circumstances across tropical forests.     

Serum Starvation and Full Confluency for Cell Cycle Synchronization of Domestic Cat (Felis catus) Foetal Fibroblasts

Nuclear transfer of domestic cat can be used as a tool to develop reproductive biotechnologies in wild felids. The importance of cell cycle phase during the nuclear transfer has been a matter of debate since the first mammalian clone was produced. The cell cycle phase of donor cells interferes on maintenance of correct ploidy and genetic reprogramming of the reconstructed embryo. The use of G0/G1 arrested donor cells has been shown to improve nuclear transfer efficiency. The present study was conducted to test the hypothesis that domestic cat foetal fibroblasts cultured up to the fifth passage and submitted to full confluency provide a higher percentage of cells at G0/G1 stage than fibroblasts cultured in serum starved media. Results demonstrated that serum starvation increased (p ≤ 0.05) the percentage of G0/G1 fibroblasts when compared with control. Moreover, the combined protocol using confluency and serum starvation was more efficient (p ≤ 0.05) synchronizing cells at G0/G1 stage than serum starvation or confluency alone for the first 3 days of treatment. In conclusion, serum starvation and full confluency act in a synergistic manner to improve domestic cat foetal fibroblast cell cycle synchronization at the G0/G1 stage.     

Significance of Non‐conventional Parameters in the Evaluation of Cooling‐induced Damage to Ram Spermatozoa Diluted in Three Different Media

The objectives of this study were two. First, to compare three base media with different sugar composition as an initial step to achieve a good chemically‐defined extender for ram sperm refrigeration. The second one, to determine which sperm quality parameters may be more useful for revealing differences between sperm samples. One medium contained 200 mm sucrose and 2.8 mm glucose (SM), another only disaccharides (D) such as sucrose, trehalose, maltose and lactose (75 mm each); and the third one (D+M) included a mix of monosaccharides (50 mm glucose, 20 mm fructose and 20 mm galactose,) and the same disaccharides as in D (50 mm each). Ram semen samples diluted in the mentioned media were refrigerated at 5°C for 1 h, and rewarmed upto 37°C in order to mimic the temperature in the female reproductive tract. Addition of monosaccharides to the extender did not produce a better preservation of motility or viability after cooling. The supplementation with other disaccharides apart from sucrose did not enhance the viability either. Thus, after cooling and rewarming, there were no significant differences in sperm viability (membrane integrity evaluated by CFDA/PI staining) or the percentage of progressive motile and rapid sperm (evaluated by CASA) between the three media. However, the percentage of viable non‐capacitated sperm evaluated by the chlortetracycline (CTC) assay was higher and sperm oxygen consumption was lower in SM than in D and in D+M. Although the apoptosis‐like markers [phosphatidylserine exposure assessed by Annexin V/CFDA staining and DNA‐damage evaluated by TUNEL assay] showed a continuous increment throughout the process with all diluents, the percentage of sperm with damaged DNA at the end of the process was significantly lower in SM than in the other two media (p < 0.01). On the basis of these results, we would make two recommendations: the use of an extender supplemented only with sucrose and glucose for ram sperm refrigeration; the inclusion of non‐conventional methods such as oxygen consumption measure, evaluation of capacitation state and apoptosis‐like markers for revealing differences between sperm samples.