Laboratory observation of siblicide with hatching asynchrony in an insect with parental provisioning

We report laboratory observation of siblicide with hatching asynchrony in the passalid beetle Cylindrocaulus patalis. Parents construct a breeding gallery in rotten logs and show complex care of offspring, including provisioning. Clutch sizes are extremely small, and only a single offspring is raised in a colony in each breeding season. We introduced field-collected colonies into an artificial gallery and recorded the behaviour of colony members. Eggs hatched at 2- to 10-day intervals in each colony. Fatal fighting invariably occurred among the larvae soon after hatching of the junior larva, and a single larva, usually the senior one, survived.     

The Nutritional Efficiency of Cannibalism and an Artificial Feed for the Growth of Tadpoles of Japanese Toad (Bufo vulgaris sp.)

Tadpoles of Japanese toad (Bufo vulgaris) were cultured by an artificial feed and by forced cannibalism from the egg until metamorphosis finished. The best growth was found in the artificial feed group, however, the highest feed efficiency was observed in the cannibalism group. The tadpoles were metamorphosed by the culture with amino acid mixture feed but no body weight increase was seen in this case. The nutritional disturbance hindered the metamorphosis.

The relative amino acid composition was constant throughout all the stages of the tadpole growth. The relative amino acid composition of the toad was diversed according to the species. Several unidentified ninhydrine-positive substances were detected on the column chromatograms of amino acid analysis of tadpoles and their adult forms.     

Pyrroloquinoline quinone (PQQ) is reduced to pyrroloquinoline quinol (PQQH2) by vitamin C,and PQQH2 produced is recycled to PQQ by air oxidation in buffer solution at pH 7.4

Measurements of the reaction of sodium salt of pyrroloquinoline quinone (PQQNa₂) with vitamin C (Vit C) were performed in phosphate-buffered solution (pH 7.4) at 25 °C under nitrogen atmosphere, using UV–vis spectrophotometry. The absorption spectrum of PQQNa₂ decreased in intensity due to the reaction with Vit C and was changed to that of pyrroloquinoline quinol (PQQH₂, a reduced form of PQQ). One molecule of PQQ was reduced by two molecules of Vit C producing a molecule of PQQH₂ in the buffer solution. PQQH₂, thus produced, was recycled to PQQ due to air oxidation. PQQ and Vit C coexist in many biological systems, such as vegetables, fruits, as well as in human tissues. The results obtained suggest that PQQ is reduced by Vit C and functions as an antioxidant in biological systems, because it has been reported that PQQH₂ shows very high free-radical scavenging and singlet-oxygen quenching activities in buffer solutions.     

Evaluation of the transpiration rate of lotus using the stem heat-balance method

To reveal the mechanism of transpiration by hydrophytes in the field, it is necessary to evaluate the transpiration rate without the effect of the evaporation from the water surface. In order to test the suitability for evaluating the transpiration rate of lotus (Nelumbo nucifera Gaertn.) leaves in the field, stem heat-balance method was applied and the obtained sap-flow rate was compared with the transpiration rate measured by weighing and with the overall canopy evapotranspiration rate by means of the eddy covariance technique. The transpiration rate estimated with the sap-flow measurements showed good agreement with that obtained from the weighing method. Lotus has many air canals in its petiole to carry oxygen-rich air to the rhizome and methane- and carbon dioxide-rich air back to the atmosphere, but there was little effect of the mass flow of air through these canals on the sap-flow rates. In the field observations, the canopy evapotranspiration rate (0.28 mm h⁻¹ at maximum) was nearly equal to the sum of the transpiration rate from all sunlit leaves (0.30 mm h⁻¹), and the contribution of the transpiration from shaded leaves and evaporation from the water surface was considered to be minor in the seasons when the leaves were fully developed. Evaluation of bulk leaf conductance revealed that the conductance in the leaf boundary layer of lotus could be low (ca. 0.23 mol m⁻² s⁻¹) because of its large leaf area. The low conductance in the leaf boundary layer would increase leaf temperature, which, in turn, would generate air circulation within the plant's ventilation system. Because there was a linear relationship between transpiration rate and the leaf-to-air vapor-pressure deficit, with no apparent maximum, high vapor-pressure deficits (3.4 kPa at maximum) did not appear to cause significant stomatal closure in lotus plants. The stomata of lotus leaves play a role as air inlets to carry oxygen-rich air to the rhizome, so their low sensitivity would help to increase air intake.     

Fluorescent labeling of a carboxyl group of sialic acid for MALDI-MS analysis of sialyloligosaccharides and ganglioside

We developed a modified method enabling stable MALDI-MS analysis and fluorescent detection of sialyl-compounds. The modification involved the amidation of sialic acid (Neu5Ac) at the position of the carboxyl group using the fluorescent reagent, 2-(2-pyridilamino)ethylamine (PAEA). In this study the following sialyl-compounds were amidated, 3′-sialyllactose (3′-SL), 6′-sialyllactose (6′-SL), and ganglioside GM3. Yields of PAEA-3′-SL, PAEA-6′-SL, and PAEA-GM3 were 45%, 60%, and 30%, respectively. The PAEA-amidation enabled fluorescence detection of structural isomers using HPLC and TLC at sensitivity levels as low as pmol. In MALDI-TOF-MS and/or MS/MS analysis in positive ion mode, PAEA-amidation provided the following advantages: suppression of preferential cleavage of Neu5Ac; enhancement of molecular-related ion intensities; simplification of MS spectra; and finally, since PAEA-amidation did not cleave the linkage between sugar and aglycon of sialylglycoconjugate, MALDI-TOF-MS and MS/MS analyses revealed the complete structure of the molecule.     

Localization of fluorescent substances in the cellular slime moldDictyostelium discoideum cells during growth and development

The localization of fluorescent substance was observed microscopically in livingDictyostelium discoideum cells. The fluorescence was localized in the vacuoles of the vegetative cells. The fluorescent vacuoles were not observed in the dead cells. The fluorescent vacuoles in the cytoplasm were lost in starved cells which are able to form an aggregate and to differentiate. The fluorescent vacuoles were not lost but decreased slightly in the cytoplasm of full grown cells and of cells grown in liquid nutrient medium for an extended period of time (stationary phase cells). On a solid substratum, fluorescent vacuoles were also lost from the cells, where the vegetative cells aggregate and form a slug-shaped mass of cells. The whole slug showed homogeneous fluorescence. In a finally constructed fruiting body, the spore mass showed fluorescence. In a spore mass, the fluorescence was not observed in the spores but in the interspore space of the spore mass. It is suggested that vegetative cells secrete fluorescent substance into the inter-cellular space in the mass of cells during development.     

Human forcing of the copepod–fish–jellyfish triangular trophic relationship

Copepods, the most abundant planktonic metazoans, constitute an intermediate trophic position between phytoplankton and higher trophic-level animals such as fish and jellyfish. Fish and jellyfish are adversaries because they often compete for prey copepods and also can be prey of each other. The classical food chain represented by phytoplankton–copepod–fish is the main process leading to efficient and sustainable production of fish as human food. At present, more than 75% of world fish stocks are fully or over exploited. On the other hand, jellyfish populations have increased world-wide, particularly in waters under significant human influences. Two such cases are seen in East Asian waters, where massive blooms of moon jellyfish (Aurelia aurita s.l.) and giant jellyfish (Nemopilema nomurai) have repeatedly occurred in recent decades, causing severe damage to local fisheries. In this article, I will review the pivotal role of copepods in marine ecosystems, particularly in the Inland Sea of Japan, where the annual fish catch per unit area is among the world’s highest. Then, I will describe an ongoing ecosystem shift from dominance by fish to dominance by jellyfish as a consequence of human forcing. Finally, I will propose to create “sato-umi”, a coastal sea with high productivity and biodiversity with wise human interaction, where copepod production would most efficiently transforms into food for humans.