Fish meal vs. corn gluten meal as a protein source for dry cat food.

To compare the effects of two dietary protein sources, fish meal (FM) and corn gluten meal (CGM), fecal moisture content, nitrogen balance and urinary excretion were examined in adult cats. The dietary protein source did not cause a significant difference in daily food intake, water intake, urine volume, dry matter digestibility or urinary nitrogen excretion, but fecal moisture content was lower (P<0.02) in the CGM group. The HCl-insoluble fraction of urinary sediment tended to be higher in the CGM group (P<0.10), although urinary pH was similar in the two groups. These results suggest that CGM is comparable with FM in respect to nutritional value and the urine acidifying effect, but FM may be preferable to CGM for the prevention of constipation and struvite urolithiasis in cats.     

Production and characterization of Raphanus sativus-Brassica rapa monosomic chromosome addition lines

Breeding of Raphanus sativus‐Brassica rapa monosomic chromosome addition lines (MALs, 2n = 19) was carried out by backcrossing the synthesized amphidiploid line, Raphanobrassica (R. sativus×B. rapa, 2n = 38, RRAA, line RA89) with R. sativus cv. ‘Shogoin’ (2n = 18, RR). In the first cross of Raphanobrassica× radish, four sesquidiploidal BC₁ plants (2n = 28, RRA, RA89‐36‐1, RA89‐31‐1, RA89‐31‐2, RA89‐31‐3) were successfully developed. In these plants, the chromosome configurations of 9II + 10I and 10II + 8I were observed frequently at first metaphase (MI) of meiosis in pollen mother cells (PMCs). The RA 89‐36‐1 plant produced many seeds in the reciprocal backcrosses with radish. About 50% of the BC₂ plants obtained from the cross of RA89‐36‐1 plant × radish were 2n = 19 plants, followed by 2n = 18 plants (24%) and 2n = 20 plants (19%). In the reciprocal cross, 2n = 19 plants were also developed at the rate of 40%. From analysis of specific morphological traits, 2n = 19 plants were classified into eight types (a‐h). When 25 selected primers were used in polyacrylamide gel electrophoresis, random amplified polymorphic DNA (RAPD) markers derived from B. rapa for each type of MAL were detected in numbers between three for e‐type and 16 for b‐type. RAPD markers specific for each type alone were from one (OPE 05‐344) for h‐type to nine for b‐type. In the g‐type, no marker specific to this type alone was observed. However, 19 bands were common between at least two types. These MAL plants exhibited predominantly the chromosome configuration of 9II + 1I at MI of PMCs, pollen and seed fertility being the same level as the radish cv. ‘Shogoin’. From the morphological traits and DNA markers, eight different MAL types among 10 expected were identified.     

Homoeological relationships between the f chromosome of Brassica rapa and the e chromosome of Brassica oleracea

Eight plants of the putative double monosomic addition line (DMAL, 2n= 20) were developed by crossing a monosomic chromosome addition line of radish [f(A)‐type monosomic addition line (MAL) (2n= 19)] carrying the f chromosome of Brassica rapa (2n= 20, AA) with another [e(C)‐type MAL (2n= 19)] having the echromosome of Brassica oleracea (2n= 18, CC). The homoeological relationships between the two alien chromosomes were investigated by morphological, cytogenetic and random amplified polymorphic DNA (RAPD) analysis. Seventeen morphological traits that were not present in the radish cv. ‘Shogoin’ were observed in both MALs and these traits were substantially exhibited in DMAL plants. At the first metaphase of pollen mother cells (PMCs), the two parental MALs showed a chromosome configuration of 9II +1I, demonstrating impossibility of recombination between the R and the added chromosomes. The DMALs formed 10II in approximately 73% of PMCs, with one bivalent showing loose pairing between two chromosomes differing in size. In an attempt to identify the two MALs by RAPD‐specific markers using 26 selected random primers, 13 and 20 bands were specific for the f(A)‐type and the e(C)‐type MALs, respectively; 12 bands were common to both MALs (26.7%). In conclusion, the f chromosome of B. rapa is homoeologous to the e chromosome of B. oleracea. The genetic domain (genes) for 17 morphological traits are linked to each homoeologous chromosome bearing 27% of the corresponding RAPD markers.     

Naidid worms (Oligochaeta, Naididae) in paddy soils as affected by the application of legume mulch and/or tillage practice

Reproduction, intrinsic rate of natural increase and population density of naidid worms were investigated in submerged paddy fields and the laboratory. No tillage plus legume-mulching increased the population density of naidid worms. Soil treatments with neither tillage nor legume mulch, and tillage practice alone, did not increase the number of worms. Dero dorsalis Ferronnière was dominant in soil of the no-tillage treatment. In laboratory experiments, legume-mulching with the proper amount of dissolved O₂ accelerated asexual reproduction of D. dorsalis through zooid budding. For the legume and aeration treatment, (N_i+1-N_i) N_i^-1 values (where N_i and N_i+1 are the populations at times t=i and t=i+1) were plotted against N_i+1. Utilizing this linear relation, this data fitted the logistic curve (r²=0.885, P<0.05). Based on the linear relation, the intrinsic rate of natural increase (r), carrying capacity (K), and doubling time (T) were calculated as 0.2125 day^-1, 12,666 m^-2, and 3.26 days, respectively. The amounts of legumes applied were highly correlated with the population of D. dorsalis, indicating that the weight of legume is a limiting factor with respect to carrying capacity. A literature review indicated a significant correlation (P<0.01) between intrinsic rate of natural increase and maximum body length of naidids with temperature conversion of the growth rate. Sexually mature worms were rarely found in submerged paddy fields. Sexual reproduction seems to be adopted in response to soil desiccation after paddy field drainage.     

Development of a multiplex PCR method for simultaneous detection of diagnostic DNA markers of five disease and pest resistance genes in potato

Multiplex PCR is practically a reasonable choice for molecular marker-assisted selection in potato breeding. We had developed and were using a multiplex PCR method for selection of resistance genes to cyst nematode (H1), Potato virus X (Rx1) and late blight (R1 and R2). Since then, more reliable and tightly linked markers for H1 and R2, and a new marker for resistance to Potato virus Y (Ry _chc ) were developed. In this article, all these superior markers, including a positive marker to eliminate PCR-failed samples, were incorporated into one multiplex PCR assay. Using the newly developed multiplex PCR technique, five plants potentially harboring all five resistance genes were selected from 96 hybrid plants approximately 5 h after DNA extraction, which is a third of the operation time compared with separate PCR reactions for each marker.     

The impact of climate change on maize yields in the United States and China

This study analyzes the impacts of climate change on maize yields using an econometric model that incorporates climate, economic, and technology variables. The major finding is climate change will not universally cause negative impacts of maize yields in the United States and China. The results of a simulation of climate change on maize yields over the period 2008-2030 show that a combination of changes in temperature and precipitation can either bring positive or negative effects on maize yields. Furthermore, variation in regional climatic and economic conditions makes the impacts of climatic change on maize yields substantially different in different regions. In this research, the impacts of climate change on maize yields are not simply examined by climate factors. Economic and technology adaptation effects on maize yields are also incorporated. Thus, even with significant changes in climate conditions that alter the maize crop’s growing environment and affect crop yields, a decrease in maize supply due to a decrease in maize yields would lead to an increase in the maize price, which in turn would induce farmers to add more investments in production inputs to raise yields. Thus, the decrease in actual yields may not be as dramatic as predicted in only climate factor considered cases. In this research, findings gained from the study can be used for early-staged policymaking decisions and advanced problem prevention programs. To ensure the continuous increase in maize yields in the future, further studies and research, as well as efficient environmental policies and actions are required.     

Essential role of Fkbp6 in male fertility and homologous chromosome pairing in meiosis

Meiosis is a critical stage of gametogenesis in which alignment and synapsis of chromosomal pairs occur, allowing for the recombination of maternal and paternal genomes. Here we show that FK506 binding protein (Fkbp6) localizes to meiotic chromosome cores and regions of homologous chromosome synapsis. Targeted inactivation of Fkbp6 in mice results in aspermic males and the absence of normal pachytene spermatocytes. Moreover, we identified the deletion of Fkbp6 exon 8 as the causative mutation in spontaneously male sterile as/as mutant rats. Loss of Fkbp6 results in abnormal pairing and misalignments between homologous chromosomes, nonhomologous partner switches, and autosynapsis of X chromosome cores in meiotic spermatocytes. Fertility and meiosis are normal in Fkbp6 mutant females. Thus, Fkbp6 is a component of the synaptonemal complex essential for sex-specific fertility and for the fidelity of homologous chromosome pairing in meiosis.     

Growth of the collembolan Folsomia candida Willem in soil supplemented with glucose

Freely available glucose improves the conditions for soil microorganisms which are utilized as food by Collembola. We examined the effects of glucose application on collembolan (Folsomia candida Willem) growth and on several biotic and abiotic soil parameters (microbial biomass, soil respiration, qCO₂, dissolved organic carbon, inorganic nitrogen, and Olson-P) in an artificial system without predatory pressure on Collembola. Glucose addition increased soil respiration and qCO₂, and decreased nutrient levels in the soil. Collembolan growth increased with increasing glucose doses. We conclude that the availability of carbon substrates can sustain collembolan growth via an improvement of microbial growth conditions.     

Ascorbate regeneration by the reduced form of 2-amino-3-carboxy-1, 4-naphthoquinone, a strong growth stimulator for bifidobacteria

Nonenzymatic reduction of dehydroascorbate into ascorbate by the reduced form (quinol form) of 2-amino-3-carboxy-1,4-naphthoquinone, a strong growth stimulator for bifidobacteria, has been found. The bimolecular reaction rate constant was evaluated as 9 M(-)(1) s(-)(1) at pH 7.0. This reaction has been successfully coupled with enzymatic regeneration of the naphthoquinol by NAD(P)H in cell-free extracts of Bifidobacterium longum 6001. The overall reaction is a regeneration of NAD(P)(+) by dehydroascorbate [or a regeneration of ascorbate by NAD(P)H], in which the naphthoquinone/quinol redox couple functions as an electron transfer mediator. Kinetic study of the reduction of dehydroascorbate with related quinol compounds suggested the significance of the amino substituent of the naphthoquinol. A mechanism of the electron transfer from the quinol to dehydroascorbate is proposed, where the first step of the reaction is a nucleophilic addition of the C(2)-amino substituent of the naphthoquinol to the C(2)-position of dehydroascorbate to form a Schiff base intermediate.