Effects of land use on population presence and genetic structure of an amphibian in an agricultural landscape

Context

Species distributions are a function of an individual’s ability to disperse to and colonize habitat patches. These processes depend upon landscape configuration and composition.

Objectives

Using Blanchard’s cricket frogs (Acris blanchardi), we assessed which land cover types were predictive of (1) presence at three spatial scales (pond-shed, 500 and 2500 m) and (2) genetic structure. We predicted that forested, urban, and road land covers would negatively affect cricket frogs. We also predicted that agricultural, field, and aquatic land covers would positively affect cricket frogs.

Methods

We surveyed for cricket frogs at 28 sites in southwestern Ohio, USA to determine presence across different habitats and analyze genetic structure among populations. For our first objective, we examined if land use (crop, field, forest, and urban habitat) and landscape features (ponds, streams, and roads) explained presence; for our second objective, we assessed whether these land cover types explained genetic distance between populations.

Results

Land cover did not have a strong influence on cricket frog presence. However, multiple competing models suggested effects of roads, streams, and land use. We found genetic structuring: populations were grouped into five major clusters and nine finer-scale clusters. Highways were predictive of increased genetic distance.

Conclusions

By combining a focal-patch study with landscape genetics, our study suggests that major roads and waterways are key features affecting species distributions in agricultural landscapes. We demonstrate that cricket frogs may respond to landscape features at larger spatial scales, and that presence and movement may be affected by different environmental factors.

     

Characterization of an antibacterial substance produced by <Emphasis Type="Italic">Pediococcus pentosaceus</Emphasis> Iz3. 13 isolated from Japanese fermented marine food

ABSTRACT:   Fermentation of raw marine food is popular in Japan, but is occasionally associated with Clostridium botulinum outbreaks. Lactic acid bacteria in fermented food produce antibacterial substances (ABS). An ABS producing strain Iz.3.13 was isolated from commercially fermented ' izushi '. The purpose of this study was to characterize strain Iz.3.13 and the ABS it produced. Strain Iz.3.13 was identified as Pediococcus pentosaceus by morphological, biochemical characteristics and 16S rDNA sequence similarity. Strain Iz.3.13ABS produced and ABS inhibited Listeria and Cl. botulinum. The ABS was inhibited by α-chymotrypsin and proteinase K, but not by catalase, lipase, or α-amylase indicating the ABS was a bacteriocin. The bacteriocin remained active at 100°C for 15 min, and pH 2–8. Mode of action of the bacteriocin against Listeria monocytogenes was bactericidal and bacteriolytic. Partial analysis of the purified bacteriocin by Edman degradation, showed a 22-amino acid residue closely related to Pediocin AcH. However, MALDI-TOF-MS analysis estimated a molecular mass of 4621.6 Da. This is a first report of a Cl. botulinum -inhibiting bacteriocin-producer from traditional Japanese fermented marine food. The bacteriocin produced by Ped. pentosaceus Iz.3.13 might have potential to ensure the safety of fermented marine food.     

RAPD variation in wild, weedy and cultivated azuki beans in Asia

RAPD (Random Amplified Polymorphic DNA) variation was assessed in 42 accessions of azuki bean (Vigna angularis) including wild, weedy and cultivated races and in three accessions of two related species used as outgroups. A much lower level of genetic variation was observed in cultivated and weedy azuki beans compared to wild azuki bean. Wild azuki bean (V. angularis var. nipponensis) has relatively high genetic variation in subtropical highlands of Asia compared to the Far East. Although cultivated azuki bean has low RAPD variation, accessions from subtropical highlands and Southeast Asia showed different RAPD features compared to those of the Far East. It is hypothesized that the cultivated azuki bean has been derived from wild azuki bean in the Far East; the high variation in wild azuki bean has been created through its natural dissemination; and the relatively low variation in cultivated azuki bean has come about through human dissemination after genetic bottleneck reduced by domestication. In addition, high genetic diversity in wild azuki bean in subtropical highlands of Asia is regarded as an important genetic resource in azuki improvement.     

精米出成率及水分含量对米的食味值影响的研究

本研究利用近红外反射光谱食味计测定了米的出成率及水分含量对食味值的影响 ,经过 Excel软件分析实验数据 ,结果表明 :在出成率 (精米重量 /糙米重量× 10 0 % )从 10 0 %～ 88%变化过程中 ,随着米的出成率下降 (白度的上升 ) ,米的营养成分 (水分、蛋白质、脂肪酸、(直 )链淀粉 ) [4]含量均呈下降趋势的同时 ,食味值呈上升趋势 ,即出成率在从 94%～ 92 % ,92 %～ 90 %、90 %～ 88%的变化过程中 ,(直 )链淀粉含量平均分别下降 6.67%、6.3 3 %、4.3 % ,蛋白质含量平均分别下降 2 .2 %、2 .0 %、1.5 %、水分含量平均分别下降 0 .2 % ,食味值平均升高 0 .5 %、1.0 %、0 .3 % ;初期水分含量为 16.0 %的样品 ,食味值上升率最大 ;同一出成率下 ,水分含量愈高食味值也愈高。因此通过观察在出成率从 10 0 %～ 88%及水分含量从 16%～ 14 %的变化过程中 ,米的出成率及水分含量对食味值的影响 ,均衡米的营养成分下降率及食味值上升率两因素 ,从保持米的营养成分和提高食味值的角度出发 ,推荐食用出成率为 92 %～ 90 %且水分含量为 16.0 %的米     

Development of a high-throughput field phenotyping rover optimized for size-limited breeding fields as open-source hardware

Phenotyping is a critical process in plant breeding, especially when there is an increasing demand for streamlining a selection process in a breeding program. Since manual phenotyping has limited efficiency, high-throughput phenotyping methods are recently popularized owing to progress in sensor and image processing technologies. However, in a size-limited breeding field, which is common in Japan and other Asian countries, it is challenging to introduce large machinery in the field or fly unmanned aerial vehicles over the field. In this study, we developed a ground-based high-throughput field phenotyping rover that could be easily introduced to a field regardless of the scale and location of the field even without special facilities. We also made the field rover open-source hardware, making its system available to public for easy modification, so that anyone can build one for their own use at a low cost. The trial run of the field rover revealed that it allowed the collection of detailed remote-sensing images of plants and quantitative analyses based on the images. The results suggest that the field rover developed in this study could allow efficient phenotyping of plants especially in a small breeding field.     

Onset of individual growth difference in larviculture of Pacific bluefin tuna <Emphasis Type="Italic">Thunnus orientalis</Emphasis> using fertilized eggs obtained from one female

We conducted a rearing experiment on Pacific bluefin tuna (PBT) larvae, which originated from one female broodstock, and determined the growth history of the larvae to clarify when the growth difference occurs. We investigated the otolith microstructure of the PBT larvae to examine the individual growth history and to predict the age and body size at the onset of individual growth difference. Since total length (TL) of fish can be back-calculated from otolith radius, we back-calculated TLs of 100 fish of 19 days post hatch (dph) divided into three size groups (small, intermediate, large). Growth difference was recognized from 3 dph (mouth opening), and the difference became larger thereafter. Growth of large-size fish was assumed to be promoted by the feeding conditions of PBT larvae.     

Primary taste center in the goatfish of genus Parupeneus

ABSTRACT:   This study was carried out to obtain fundamental information on the morphology of the primary taste center in the goatfish of genus Parupeneus. The primary taste center includes a dorsal facial lobe (dFL), ventral facial lobe (vFL) and vagal lobe (VL). The dFL is extraordinarily developed rostrocaudally to occupy the dorsal surface of the medulla. The vFL extends as a longitudinal column between the dFL and VL, and its rostral end connects to the proximal portion of the dFL at the level of most anterior medulla. The VL appears slightly caudal to the rostral end of vFL as a longitudinal column and reaches more caudally than the facial lobe (FL). The dFL includes tubercular and laminated structures. Each tubercle consists of four layers: a marginal layer, a superficial molecular layer, a cell-cluster layer and a deep layer. Sublaminar organization was also found in the cell-cluster layer. No laminar organization was found in either the vFL or VL but distinct clusters of small cells were frequently seen throughout both the lobes. Tracing experiments with the carbocyanine dye diI show that the facial fibers end in the entire dFL and vFL and the anterior portion of the intermediate nucleus of the facial lobe (NIF), while glossopharyngeal fibers terminate in the dorsolateral portion of the anterior VL and the intermediate portion of NIF. Trigeminal fibers project only to the most lateral aspects of the anterior vFL in addition to normal targets such as spinal trigeminal and medial funicular nuclei.     

Improvement of ovulation induction by additive injection of 17,20β‐Dihydroxy‐4‐pregnen‐3‐one after human chorionic gonadotropin administration in a pelagic egg spawning marine teleost,nibe croaker Nibea mitsukurii (Jordan & Snyder)

This study aimed to develop the consistent ovulation induction method in a pelagic egg spawning marine teleost, nibe croaker Nibea mitsukurii. Attempts to induce oocyte maturation and ovulation in nibe croaker using human chorionic gonadotropin (hCG; 0.5 IU g^?1) resulted in the normal progression of oocyte maturation and hydration, but a failure to induce ovulation in many individuals. This ovulation disorder was similarly observed even when the dose of hCG was increased 10 times (5 IU g^?1) or decreased to one tenth (0.05 IU g^?1), indicating that it cannot be completely overcome solely by hCG administration. However, this ovulation disorder could be completely overcome by subsequent administration of 17,20β‐dihydroxy‐4‐pregnen‐3‐one (DHP) at the appropriate dose (0.5 μg g^?1) and time (20 h after hCG administration). An increase in the number of individuals that ovulated due to DHP administration led to an increase in individuals producing larvae, resulting in an approximately threefold increase in the estimated number of larvae produced compared with the group of fish administered hCG alone. Thus, this ovulation induction method using DHP administration after hCG was demonstrated to overcome the ovulation disorder in nibe croaker and could be applicable to commercially important species with similar ovulation problems.