Hapalotrema (Digenea : Spirorchidae) in the green turtle (Chelonia mydas) in Australia

Hapalotrema mehrai Rao, 1976 and Hapalotrema postorchis Rao, 1976 (Digenea: Spirorchidae) are redescribed from the heart and pulmonary arteries of the green turtle, Chelonia mydas, from Moreton Bay in south-eastern Queensland. Hapalotrema pambanensis Gupta and Mehrotra, 1981 from C. mydas in India is made a synonym of H. mehrai. Hapalotrema dorsopora Dailey, Fast and Balazs, 1993 from C. mydas from Hawaii was described with a dorsally opening uterine pore, but this is found to be the opening of Laurer's canal; therefore H. dorsopora is also made a synonym of H. mehrai. In addition to differences in the numbers of testes and general dimensions, H. mehrai and H. postorchis differ in the development of Laurer's canal and in the absence of a canalicular seminal receptacle in H. postorchis.

Assessment of transient gene expression in plant tissues using the green fluorescent protein as a reference

Four different promoters (35S and enhanced 35S of the cauliflower mosaic virus, polyubiquitin of maize and actin1 of rice) were compared in a transient assay using maize leaves and particle bombardment. A gene encoding the jellyfish green fluorescent protein (GFP) driven by the 358 promoter was used as an internal standard to monitor the effectiveness of each bombardment. Normalisation of the transient expression assay using the GFP reference significantly reduced the variability between separate bombardments and allowed for a rapid and accurate evaluation of different promoters in microprojectile-bombarded leaves.

Development of the pulmonary surfactant system in the green sea turtle, Chelonia mydas

This study describes the developmental changes in pulmonary surfactant (PS) lipids throughout incubation in the sea turtle, Chelonia mydas. Total phospholipid (PL), disaturated phospholipid (DSP) and cholesterol (Chol) harvested from lung washings increased with advancing incubation, where secretion was maximal at pipping, coincident with the onset of pulmonary ventilation. The DSP/PL ratio increased, whereas the Chol/PL and the Chol/DSP ratio declined throughout development. The phospholipids, therefore, are independently regulated from Chol and their development matches that of mammals. To explore whether hypoxia could elicit an effect on the development of the PS system, embryos were exposed to a chronic dose of 17% O-2 for the final similar to 40% of incubation. Hypoxia did not affect incubation time, absolute, nor relative abundance of the surfactant lipids, demonstrating that the development of the system is robust and that embryonic development continues unabated under mild hypoxia. Hypoxia-incubated hatchlings had lighter wet lung weights than those from normoxia, inferring that mild hypoxia facilitates lung clearance in this species. (C) 2001 Elsevier Science B.V. All rights reserved.

Temperature variation within and between nests of the green sea turtle, Chelonia mydas (Chelonia : Cheloniidae) on Heron Island, Great Barrier Reef

Four temperature data-loggers were placed in each of five green sea turtle nests on Heron Island in the 1998-99 nesting season. Temperatures in all nests increased as incubation progressed due to general sand heating and increased metabolic heat production of the developing embryos. Even at the top of nests no daily diurnal fluctuation in temperature was evident. The temperature of eggs in the middle of the nest increased above those in the nest periphery during the last third of incubation. However, this metabolic nest heating would have little effect on hatchling sex ratio because it occurred after the sex-determining period. Small differences in temperature between regions of a nest persisted throughout incubation and may be important in ensuring the production of at least some individuals of the opposite sex in nests that have temperatures close to either the all-male or all-female determining temperatures. Location and degree of shading of nests had little effect on mean nest temperature, but deeper nests were generally cooler and therefore were predicted to produce a higher proportion of males than were shallower nests. Nest temperature profile data indicated that the 1998-99 nesting season on Heron Island would have produced a strongly female-biased sex ratio amongst hatchlings.

Incubation temperature, energy expenditure and hatchling size in the green turtle (Chelonia mydas), a species with temperature-sensitive sex determination

Eggs from the Heron Island, Great Barrier Reef, nesting population of green turtles (Chelonia mydas) were incubated at all-male-determining (26 degreesC) and all-female-determining (30 degreesC) temperatures. Oxygen consumption and embryonic growth were monitored throughout incubation, and hatchling masses and body dimensions were measured from both temperatures. Eggs hatched after 79 and 53 days incubation at 26 degreesC and 30 degreesC respectively. Oxygen consumption at both temperatures increased to a peak several days before hatching, a pattern typical of turtle embryos, and the rate of oxygen was higher at 30 degreesC than 26 degreesC. The total amount of energy consumed during incubation, and hatchling dimensions, were similar at both temperatures, but hatchlings from 26 degreesC had larger mass, larger yolk-free mass and smaller residual yolks than hatchlings from 30 degreesC. Because of the difference in mass of hatchlings, hatchlings from 30 degreesC had a higher production cost.

Effect of aestivation on muscle characteristics and locomotor performance in the Green-striped burrowing frog, Cyclorana alboguttata

The Green-striped burrowing frog. Cyclorana alboguttata survives extended drought periods by burrowing underground and aestivating. These frogs remain immobile within cocoons of shed skin and Mucus during aestivation and emerge from their burrows upon heavy rains to feed and reproduce. Extended periods of immobilisation in mammals typically result in muscle atrophy and a decrease in muscle performance. We examined the effect of aestivation and hence prolonged immobilisation, on skeletal Muscle mass. in vitro muscle performance, and locomotor performance in C. alboguttata. Frogs were aestivated in soil for 3 months and were compared with control animals that remained active, were fed, and had a continual supply of water. Compared to the controls, the wet mass of the gastrocnemius. sartorius, gracilus major. semimembranosus. peroneus, extensor cruris, tibialis posticus and tibialis anticus longus of aestivators remained unchanged indicating no muscle atrophy. The in-vitro performance characteristics of the gastroenemius muscle were maintained and burst swimming speed Was Unaffected, requiring no recovery from the extended period of immobilisation associated with aestivation. This preservation of muscle size, contractile condition and locomotor performance through aestivation enables C. alboguttata to compress their life history into unpredictable windows of opportunity, whenever heavy rains occur.

Shoot control of hypernodulation and aberrant root formation in the har1-1 mutant of Lotus japonicus

The har1-1 mutant of Lotus japonicus B-129-S9 Gifu is characterized by two phenotypes: greater than normal nodulation (hypernodulation) and significantly inhibited root growth in the presence of its microsymbiont Mesorhizobium loti strain NZP2235. We demonstrate that the two traits co-segregate, suggesting a single genetic alteration involving developmental pleiotropy. A cross between the mutant and genotype Funakura (with wild-type root and nodule morphology) demonstrated Mendelian recessive segregation of both phenotypes (root and nodule) in 216 F2 individuals. Using DNA-amplification fingerprinting polymorphisms in Gifu har1-1 and Funakura, the mutant locus was positioned between two markers at about 7 and 13 cM distance. Reciprocal hypocotyl grafting of shoots and roots showed that the hypernodulation and reduced root phenotypes are both predominantly controlled by the shoot.

Nocturnal activity in the green sea turtle alters daily profiles of melatonin and corticosterone

In nature, green turtles (Chelonia mydas) can exhibit nocturnal activity in addition to their typically diurnal activity cycle. We examined whether nocturnal activity in captive and free-living green turtles altered daily plasma profiles of melatonin (MEL) and corticosterone (CORT). In captivity, diurnally active green turtles expressed distinct diel cycles in MEL and CORT; a nocturnal rise was observed in MEL and a diurnal rise was observed in CORT. However, when induced to perform both low- and high-intensity nocturnal activity, captive green turtles exhibited a significant decrease in MEL, compared to inactive controls. In contrast, plasma CORT increased significantly with nocturnal activity, and further, the relative increase in CORT was correlated with the intensity of the nocturnal behavior. In free-living green turtles that performed nocturnal activity including: nesting, mate searching, and feeding/swimming behaviors, plasma profiles in MEL and CORT exhibited relatively little, or no, daily fluctuation. Our findings demonstrate that nocturnal activity in green turtles is often associated with MEL and CORT profiles that resemble those measured during the day. We speculate that these conspicuous changes in MEL and CORT during nocturnal activity could either support or promote behaviors that enable acquisition of transient resources important to the survival and reproductive success of green turtles. (C) 2002 Elsevier Science (USA).

Is re-feeding efficiency compromised by prolonged starvation during aestivation in the green striped burrowing frog, Cyclorana alboguttata?

We examined several morphological parameters of the gastrointestinal tract, digesta passage rates, and nutrient assimilation efficiencies of Green-striped Burrowing frogs (Cyclorana alboguttata) following prolonged fasting during three months of aestivation and compared these with frogs that had been continuously fed. Whole animal digesta passage rates were significantly reduced following three months aestivation as a result of a decreased digesta evacuation rate from the stomach. Furthermore, food was selectively retained in the small intestine for an increased time following three months of aestivation. Overall digestibility of food and nitrogen, carbon, and energy extraction efficiencies were not significantly different from control values following three months of aestivation. These findings suggest that C. alboguttata employs reduced digesta passage rates so as to maximize nutrient assimilation efficiency following prolonged food deprivation during aestivation. (C) 2003 Wiley-Liss, Inc.

Effect of aestivation on long bone mechanical properties in the green-striped burrowing frog, Cyclorana alboguttata

The green-striped burrowing frog, Cyclorana alboguttata, survives extended drought periods by burrowing underground and aestivating. These frogs remain immobile within cocoons of shed skin and mucus during aestivation and emerge from their burrows upon heavy rains to feed and reproduce. Extended periods of immobilisation in mammals typically result in bone remodelling and a decrease in bone strength. We examined the effect of aestivation and, hence, prolonged immobilisation on cross-sectional area, histology and bending strength in the femur and tibiolibula of C alboguttata. Frogs were aestivated in soil for three and nine months and were compared with control animals that remained active, were fed and had a continual supply of water. Compared with the controls, long bone size, anatomy and bending strength remained unchanged, indicating an absence of disuse osteoporosis. This preservation of bone tissue properties enables C. alboguttata to compress the active portions of their life history into unpredictable windows of opportunity, whenever heavy rains occur.