Carbon dioxide exchange of larch (Larix gmelinii) cones during development

Larch (Larix gmelinii (Rupr.) Rupr.) cone scales are green, but little is known of their photosynthetic role in cone development or about how they differ in gas exchange characteristics from needle leaves. In contrast to leaf photosynthesis (Pleaf), we found that stomatal regulation of cone photosynthetic rate (Pcone) was marginal because the photosynthetic carbon came from internal recycling of respiratory carbon dioxide (CO2). Photosynthetic recycling of respired CO2 was confirmed by the finding that the intercellular CO2 concentration (Ci) in cone scales was much higher than ambient [CO2]; also, there was a positive correlation between Pcone and Ci, whereas Pleaf was almost constant as Ci varied. Low chlorophyll (Chl) concentration was a limiting factor for Pcone, but not for Pleaf, as indicated by the correlation between Pcone and chlorophyll concentration. Moreover, chlorophyll utilization efficiency (Psat/Chl a+b) for cone scales was lower than that for leaves. In both cones and leaves, nitrogen (N) was positively correlated with photosynthetic capacity (P), but the P/N value was much lower for cones than for leaves. For both organs, the ratio of respiration to N was broadly similar. Although mature cones have no photosynthetic capacity, Pcone of young cones was as high as 5.3 micromol m(-2) s(-1), about 1.26 times the value of Pleaf, and accounted for the refixation of 30-40% of the respiratory CO2 produced by cones, equivalent to the photosynthetic capacity of a bundle of short shoots near each cone. Thus, Pcone may be an important additional source of photosynthate for cones, given the weak assimilating capacity of leaves that are not fully expanded during cone development.     

A critical role for the innate immune signaling molecule IRAK-4 in T cell activation

IRAK-4 is a protein kinase that is pivotal in mediating signals for innate immune responses. Here, we report that IRAK-4 signaling is also essential for eliciting adaptive immune responses. Thus, in the absence of IRAK-4, in vivo T cell responses were significantly impaired. Upon T cell receptor stimulation, IRAK-4 is recruited to T cell lipid rafts, where it induces downstream signals, including protein kinase C activation through the association with Zap70. This signaling pathway was found to be required for optimal activation of nuclear factor kappaB. Our findings suggest that T cells use this critical regulator of innate immunity for the development of acquired immunity, suggesting that IRAK-4 may be involved in direct signal cross talk between the two systems.     

Inheritance of male flower production in Cryptomeria japonica (sugi) estimated from analysis of a diallel mating test

Context

Clonal variation of flower production has been investigated thoroughly in coniferous tree species because of the importance of flowering in seed production from seed orchards. However, the inheritance of flower production by progeny test has not been previously studied well, so the heritability of male flower production of Cryptomeria japonica, the most important species for forestry and the main cause of pollinosis in Japan, was estimated to provide fundamental data for pollen control in seed orchards and plantation forests.

Methods

Male flower production in C. japonica was investigated for three years using 20 full-sib families created by a diallel mating design with six parents using gibberellin treatment to promote flowering.

Results

The narrow-sense individual tree heritability of male flower production in each year was estimated as ranging from 0.777?±?0.339 to 1.050?±?0.346 by sib analyses. The contribution of general combining ability to the total variance varied from 24.1 to 35.6?%. The highest contribution of specific combining ability was 1.42?%. By selecting the top 50?% of parental clones for reduced male flower production, the genetic gain in lowering male flower productivity was predicted as 46.1?C53.0?%.

Conclusion

Our results suggest that male flower production in C. japonica is under strong genetic control and that control of male flowering by breeding is possible with a well-designed program.     

Discrimination among host tree species by the ambrosia beetle Platypus quercivorus

The ambrosia beetle Platypus quercivorus is a vector for the fungus that causes Japanese oak wilt, and susceptibility to infestation by P. quercivorus varies by tree species. We postulated that P. quercivorus discriminates among host tree species differing in susceptibility to attack. To test this postulate, we counted the number of flying male beetles (NFM), the number of holes bored by male beetles (NH), and the number of flying female beetles (NFF) per unit area of bark surface in three fagaceous tree species: Quercus crispula (with high susceptibility to infestation) and Q. serrata and Castanea crenata (both with low susceptibility). NFM and NH were used to calculate the proportion of male beetles that bored holes out of those that flew to the tree (PBM). We used generalized additive models to predict NFM, NFF, and PBM. The locations of trees, expressed as x and y coordinates, numbers of weeks after the first male beetle’s flying (WEEK), diameters of trees 130 cm above ground (DBH), and tree species (SP) were incorporated into the models as candidate explanatory variables. The best-fit models for NFM and NFF included WEEK and DBH and the effect of location; SP was not included in the models. For PBM, the best-fit model included WEEK, DBH, and SP. The results indicate that male P. quercivorus prefer Q. crispula to Q. serrata and C. crenata and that selection is made before boring holes on trees, but that P. quercivorus do not discriminate among host species when they fly to trees.     

Circulating testosterone and inhibin levels at different ages in the male beluga (Delphinapterus leucas)

This study is the first report on circulating testosterone and inhibin levels in a species of whales, the beluga. Circulating testosterone and immunoreactive (ir-) inhibin levels in two captive male belugas ("Nack", originally from Canada and "Duke", from the Okhotsk Sea) were measured every month for 9 years between 1995 and 2003. Assuming that clearly increased testosterone levels in the circulation indicates that the belugas had reached sexual maturity, at the ages of 10 ("Nack") and 11 years old ("Duke"). Their testosterone levels before the significant increase (pre-pubertal) were 0.42 ± 0.07 ng/ml (n=18) and 0.35 ± 0.10 ng/ml (n=18) and, those of after the increase (maturity) were 1.65 ± 0.14 ng/m l (n=74) and 2.06 ± 0.14 ng/ml (n=74). Circulating ir-inhibin levels before sexual maturity were 0.78 ± 0.04 ng/ml (n=18) and 0.64 ± 0.04 ng/ml (n=15) and, after sexual maturity were 0.52 ± 0.02 ng/ml (n=56) and 0.43 ± 0.02 ng/ml (n=67). Seasonal changes were observed in the testosterone levels after sexual maturity and the levels increased during March and April in Canadian origin "Nack", and peaked in February in Okhotsk origin "Duke". Circulating ir-inhibin level gradually decreased as they aged. A negative correlation between the circulating testosterone and ir-inhibin was observed. No seasonal changes were observed in the ir-inhibin levels after sexual maturity. These data will surely correspond to clarification of endocrinology and the successful reproduction of the beluga.     

Coxa morphologically adapted to large egg in aepyornithid species compared with various palaeognaths

The coxa of palaeognaths including extinct aepyornithid species was compared by means of osteology, computed tomography (CT) imaging and macroscopic anatomy. The pre-acetabular area of the ilium was proportionally much larger in width and height in aepyornithid species than in other extant palaeognaths. The post-acetabular area of the ilium, ischium and pubis was relatively short and bilaterally extended in aepyornithid species. Although the Aepyornis species might have produced egg with a major axis exceeding 300?mm in major axis, the short post-acetabular coxa and widely opened ischium and pubis would not have been able to stably hold the eggs in the posterior space of the pelvic cavity unlike the situation in the ostrich. As aepyornithid species resembled the kiwi in measurement ratios of length and width in the pre-acetabular area, a functional-morphological model of the coxa in the aepyornithid species can be proposed based on that of the kiwi. From our data, we suggest that the extinct species of Aepyornis and Mullerornis species effectively used the anterior space of the pelvic cavity to support their extraordinary large egg.     

Amputation for histiocytic sarcoma in a cat

A 9-year-old spayed female domestic shorthair cat presented with a skin lesion of the left tarsus. The lesion was biopsied and, based on the microscopic appearance and immunohistochemical characteristics, histiocytic sarcoma was diagnosed. Amputation was performed with improved demeanor seen postoperatively. However, between 44 and 60 days following the surgery, relapse of skin lesions appeared in multiple locations, including at the previous amputation site, and euthanasia was elected. This is the first report of a histiocytic sarcoma treated with amputation in a cat.     

Intestinal Tritrichomonas suis (=T. foetus) infection in Japanese cats

Tritrichomonas suis (=T. foetus) has recently been reported to be a causative agent of chronic large-bowel diarrhea in cats. While the disease was previously attributed to Pentatrichomonas hominis, the etiologic agent for feline trichomonal diarrhea was identified as T. suis. Although feline trichomonosis due to T. suis has been reported at prevalences ranging from 14 to 31% in Europe and the U.S., no reports of the pathogen have been published to date in Japan. In 2008, however, we encountered a case of feline trichomonosis at the Veterinary Teaching Hospital of Hokkaido University. The parasite was identified as T. suis by nested PCR amplification of partial internal transcribed spacer region 1 and 5.8S ribosomal RNA gene sequences with T. suis-specific primers and DNA sequencing of the amplified products. We then conducted surveys for feline trichomonosis in three different animal hospitals using either cultivation and/or PCR-based assays. The results revealed that 13 of 147 samples (8.8%) were positive for T. suis, and that 5 of the 13 infected cats, which ranged between 1 month and 7.5 years-old, showed chronic diarrhea. Seven of the infected cats were purebred and 6 were mixed breed. These findings suggested that feline trichomonosis is prevalent in Japan, and that T. suis may play a role as a causative agent of feline chronic diarrhea.     

Use of bean husk as an easily digestible fiber source for activating the fibrolytic rumen bacterium Fibrobacter succinogenes and rice straw digestion

A series of in sacco and in vitro studies were carried out to evaluate bean husks for activation of fibrolytic rumen bacteria and rice straw digestion. First, lablab bean husk, chickpea husk and rice straw were suspended in the rumen of sheep to analyze the bacterial consortium developed on each fiber source. Known members of fiber‐associating bacteria were found on both lablab bean husk and rice straw, but some of these bacteria were lacking on chickpea husk. Second, a pure culture study was carried out using six strains of Fibrobacter succinogenes. Both husks stimulated the growth of all tested strains, including a strain that did not grow on rice straw. The strain OS128 that showed the highest growth on rice straw displayed even higher growth on lablab bean husk without a time lag. Finally, two‐step incubations were carried out to determine whether prior incubation of rumen fluid with husks stimulates subsequent rice straw digestion. Higher digestibility of rice straw was recorded in the second‐round incubation following the first incubation with bean husks. These results suggest that the tested bean husks improve the digestion of rice straw by activating fibrolytic F. succinogenes and other associated bacteria.