Cloning and expression of cDNA encoding the complete prepro-form of an isoform of Der f 1, the major group 1 allergen from house dust mite Dermatophagoides farinae

cDNA clones encoding a major house dust mite allergen, Der f 1, were isolated from a Dermatophagoides farinae cDNA library by plaque immunoscreening using rabbit anti-Der f 1 serum. The sequences cover the complete open reading frame encoding the prepro-form. The sequence is different from previously reported cDNA of Der f 1 in six bases and the encoded amino acid sequence is different in two residues. Pro-forms of Der f 1 and its mutant, in which the N-glycosylation motif was disrupted, expressed in Pichia pastoris were converted to the mature forms by an in vitro activation process and they showed significant IgE-binding. The biologically active rDer f 1 molecules would be useful for diagnostic testing and allergen-specific immunotherapy. In contrast, Der f 1 directly expressed in Escherichia coli without the prosequence had very low IgE binding. The hypoallergenic Der f 1 polypeptide could be useful for safer and more effective immunotherapy.     

Migration of prospindle before the first asymmetric division in germinating spore of Marchantia polymorpha

The development of the plant body starts with spore germination in bryophytes. In many cases, the first division of the spore occurs after germination and cell elongation of the spore. In Marchantia polymorpha, asymmetric division occurs upon spore germination to generate two daughter cells: the larger one retains the ability to divide and develops into the thallus via sporeling or protonema, while the smaller one maintains tip growth and differentiates into the first rhizoid, providing a scaffold for initial development. Although spore germination of M. polymorpha was described in the 19th century, the intracellular processes of the first asymmetric division of the spore have not been well characterized. In this study, we used live-cell imaging analyses to elucidate microtubule dynamics during the first asymmetric division concomitantly with germination. In particular, we demonstrated that the preprophase band was not formed in the spore and that the bipolar prospindle, which is a microtubule structure surrounding the nucleus during prophase, migrated from the center to the periphery in the spore, suggesting that it was the earliest visible sign of cell polarity. We also showed that the occurrence of asymmetric division depended on actin filaments. Our findings regarding the first division of the spore in M. polymorpha will lead to a better model for cell-autonomous asymmetric division in plants.     

Scaling of swim speed and stroke frequency in geometrically similar penguins: they swim optimally to minimize cost of transport

It has been predicted that geometrically similar animals would swim at the same speed with stroke frequency scaling with mass^−1/3. In the present study, morphological and behavioural data obtained from free-ranging penguins (seven species) were compared. Morphological measurements support the geometrical similarity. However, cruising speeds of 1.8–2.3 m s⁻¹ were significantly related to mass^0.08 and stroke frequencies were proportional to mass^−0.29. These scaling relationships do not agree with the previous predictions for geometrically similar animals. We propose a theoretical model, considering metabolic cost, work against mechanical forces (drag and buoyancy), pitch angle and dive depth. This new model predicts that: (i) the optimal swim speed, which minimizes the energy cost of transport, is proportional to (basal metabolic rate/drag)^1/3 independent of buoyancy, pitch angle and dive depth; (ii) the optimal speed is related to mass^0.05; and (iii) stroke frequency is proportional to mass^−0.28. The observed scaling relationships of penguins support these predictions, which suggest that breath-hold divers swam optimally to minimize the cost of transport, including mechanical and metabolic energy during dive.     

A childhood-onset intestinal toxemia botulism during chemotherapy for relapsed acute leukemia

Background

Botulism is a potentially fatal infection characterized by progressive muscle weakness, bulbar paralysis, constipation and other autonomic dysfunctions. A recent report suggested that cancer chemotherapy might increase the risk for the intestinal toxemia botulism in both adults and children.

Case presentation

We report a 5-year-old boy, who developed general muscle weakness, constipation, ptosis and mydriasis during the third induction therapy for relapsed acute myeloid leukemia. He had recent histories of multiple antibiotic therapy for bacteremia and intake of well water at home. Repeated bacterial cultures identified Clostridium botulinum producing botulinum neurotoxin A. Botulinum toxin A was isolated from his stools at 17, 21, and 23 days after the onset. Symptoms were self-limiting, and were fully recovered without anti-botulinum toxin globulin therapy.

Conclusion

This is the second report of a pediatric case with cancer chemotherapy-associated intestinal toxemia botulism. Our case provides further evidence that the immunocompromised status due to anti-cancer treatments increases the risk for the development of botulism at all ages in childhood.

     

Extreme winter aggregation of invasive rainbow trout in small tributaries: implications for effective control

Because of their high economic and recreational value, salmonids have been extensively introduced worldwide and are responsible for significant impacts on native ecosystems. However, effective methods for controlling or eradicating introduced populations of salmonids are still limited, particularly in large river systems. Here, we demonstrated that invasive rainbow trout Oncorhynchus mykiss immigrated to and extremely aggregated in small tributaries during the winter, which can be utilized for effective population control. Seasonal census was conducted in 10 small tributaries of the Otofuke River in the Tokachi River basin, central Hokkaido, Japan. Winter abundance was 8–125 times higher than summer abundance in four of the tributaries where water velocities were low. Relatively large individuals (200–350 mm) aggregated in several pools at an unusually high density (>2–3 individuals/m² or 170–440 individuals per pool). Females were common in the small tributaries in the winter, but not in the summer. Therefore, removal of invasive rainbow trout may be best practised in such small tributaries during early winter. Because many stream fishes overwinter in specific, often limited, habitats, more attention should be paid to such winter habits in the effective management of non-native fish species.     

Symbiotic <Emphasis Type="Italic">Chlorella variabilis</Emphasis> strain, 1 N,can influence the digestive process in the host <Emphasis Type="Italic">Paramecium bursaria</Emphasis> during early infection

The association between the ciliate Paramecium bursaria and symbiotic Chlorella spp. is mutually beneficial. However, this relationship is facultative mutualism because both the host and the symbiotic algae can grow by themselves. This association is easily re-established by mixing the two species together. Following algal mixing, some algae become enclosed in the digestive vacuole membrane of the paramecia to which both acidosomes and lysosomes fuse. To establish endosymbiosis, some algae acquire temporal resistance to the host lysosomal enzymes in the digestive vacuoles. We examined whether the algae influence the differentiation of the host digestive process using LysoSensor staining to evaluate the acidification of the digestive vacuoles. Furthermore, to assess lysosomal fusion with the digestive vacuole, Gomori’s staining was conducted. Acidification and lysosomal fusion occurred later in digestive vacuoles containing living algae than in those containing boiled algae or latex spheres. This phenomenon was observed when the living algae were maintained under a constant light condition. These results suggest that the algae release some unknown factor in response to light exposure, and the factor may be associated with the alteration of the host digestive process, indicating that the living algae can influence the host digestive processes during early algal infection.     

Molecular cloning and preliminary expression analysis of banded dogfish (Triakis scyllia) CC chemokine cDNAs by use of suppression subtractive hybridization

Suppression subtractive hybridization was carried out by using cDNAs of peripheral white blood cells (PWBCs) of banded dogfish (Triakis scyllia) after phorbol 12-myristate 13-acetate (PMA) stimulation. The Trsc-SCYA107, MIP31 and MIP32 clones contained an open reading frame encoding 97, 99 and 97 amino acids, respectively. Comparison of the deduced amino acids showed that the banded dogfish MIP31 and MIP32 sequences shared 42.3% and 40.0% identity with human SCYA20, respectively, while the Trsc-SCYA107 sequence shared 50.6, 44.2 and 42.0% identity with the catshark (Scyliorhinus canicula) Scca-SCYA107, rainbow trout (Oncorhynchus mykiss) CK4A and CK4B, respectively. The genomic sequences of banded dogfish Trsc-SCYA107, MIP31 and MIP32 contain four exons and three introns, and MIP31 and MIP32 shared the same intron/exon organization with that of human. The MIP31 and MIP32 genes of lipopolysaccharide (LPS)-unstimulated banded dogfish were expressed in gill, kidney and liver, while Trsc-SCYA107 mRNA was detected in various tissues except for brain. However, the constitutive expression of MIP32 gene was much lower than the Trsc-SCYA107 and MIP31 genes. RT-PCR analysis of the Trsc-SCYA107 expression in tissues of LPS-stimulated fish showed enhanced expression at 24 h poststimulation in the gill, heart, leydig, spleen and testes, while the expression of MIP31 and MIP32 was not influenced by LPS-stimulation in vivo. Furthermore, a relative increase in the expression of the Trsc-SCYA107 and MIP32 genes in PWBCs was observed at 1–12 h poststimulation with PMA and LPS, with maximal expression observed at 3 h, while MIP31 expression was observed at 3–12 h poststimulation only with PMA.     

Attenuated thermoregulatory responses with increased plasma osmolality in obese subjects during two seasons

Obese subjects may be more vulnerable to injury from heat stress, and appear to be less efficient at thermoregulation. Sweat rate, tympanic temperature and osmolality in obese subjects were investigated in Japan during two seasons. The purpose of this study was to examine the relationship between obesity, thermoregulatory response and season. Five obese (BMI, 32.0?±?4.9 kg/m²) and five non-obese (BMI, 23.2?±?2.9 kg/m²) men participated in this experiment at latitude 35°10′ N and longitude 136°57.9′E. The average atmospheric temperature was 29.1?±?1.0 °C in summer and 3.3?±?1.4 °C in winter. Tympanic temperature and sweat rate were measured during leg water immersion at 42 °C for 30 min. Blood samples were analyzed for plasma osmolality. The relationship between tympanic temperature and sweat rate decreased significantly in obese compared to in non-obese subjects in both seasons, there being a lowered sweat rate for any core temperature in obese subjects. Plasma osmolality was significantly higher in obese than in non-obese subjects in both seasons. Thermal sensation increased significantly in non-obese than in obese in winter but not in summer. Our data show that thermoregulatory responses are attenuated in obese subjects compared with controls, suggesting that obese people are at increased risk of heat-related illnesses.     

Direct uptake and degradation of DNA by lysosomes

Lysosomes contain various hydrolases that can degrade proteins, lipids, nucleic acids and carbohydrates. We recently discovered “RNautophagy,” an autophagic pathway in which RNA is directly taken up by lysosomes and degraded. A lysosomal membrane protein, LAMP2C, a splice variant of LAMP2, binds to RNA and acts as a receptor for this pathway. In the present study, we show that DNA is also directly taken up by lysosomes and degraded. Like RNautophagy, this autophagic pathway, which we term “DNautophagy,” is dependent on ATP. The cytosolic sequence of LAMP2C also directly interacts with DNA, and LAMP2C functions as a receptor for DNautophagy, in addition to RNautophagy. Similarly to RNA, DNA binds to the cytosolic sequences of fly and nematode LAMP orthologs. Together with the findings of our previous study, our present findings suggest that RNautophagy and DNautophagy are evolutionarily conserved systems in Metazoa.