Estimation of gillnet selectivity curve by maximum likelihood method

ABSTRACT: A maximum likelihood method of estimating gillnet selectivity when data are obtained by gillnet fleets consisting of several nets of differing mesh size is presented in this paper. The SELECT model is expanded by application of the relative length (i.e. the ratio of fish length to mesh size) to obtain a master curve of gillnet selectivity. Four kinds of functional model, normal, lognormal, skew-normal and bi-normal are fitted to the data. In addition, two cases in which the relative fishing intensity is either estimated or fixed by catch effort are compared. The bi-normal model has the lower model deviance regardless of whether the relative fishing intensity is estimated or not. The estimation of relative fishing intensity by catch effort is also examined in which the estimates of the parameter of the SELECT model are compared with the catch effort as determined by the number of nets of each mesh size used. For the bi-normal model these quantities compare well. Thus, it is concluded that this method gives reliable estimates even if data for each mesh size is obtained with different catch efforts.     

日本沿海捕鳗笼的网目选择性

1995~2000年在东京湾进行的套网法实验,结果表明:网目尺寸为21·0、18·1、15·5、13·6、11·6mm的笼网目选择率在星康吉鳗全长035·50cm、l>32·50cm、l>27·50cm、l>26·50cm、l>24·00cm时,全长选择率几乎接近于1·00,50%选择全长分别为29·80、26·80、23·00、22·00、20·00cm;选择域为3·80、4·30、3·50、3·00、3·00cm。依据AIC理论,套网和实验网的网目接近时,套网的影响显著;Single curve model所得到的主选择性曲线可更好地反映网目选择性。50%选择相对体周长MGc1·11,选择域为0·52。01·60,选择率趋向于1·00。     

Antihyaluronidase action of ellagic acid effectively prevents polyspermy as a result of suppression of the acrosome reaction induced by sperm-zona interaction during in vitro fertilization of porcine oocytes

The present study was conducted to examine the effects of three tannin relatives (tannic acid, TA; gallic acid, GA; and ellagic acid, EA) on antihyaluronidase and reactive oxygen species (ROS) scavenging activity, in vitro fertilization (IVF) parameters, and the acrosome reaction (AR) induced by sperm-zona interaction. Among the three tannin relatives, TA and EA showed the strongest potency for blocking the hyaluronidase activity of boar sperm, with concentration-dependent inhibition over the range of 2-10 microg/ml. In contrast, ROSs were effectively scavenged by TA and GA, but not EA. When cumulus-free oocytes were inseminated in IVF medium containing 5 microg/ml of the tannin relatives, polyspermy was significantly reduced by TA and EA (32 and 29%, respectively) compared with oocytes treated with or without GA (51 and 69%, respectively) under conditions that maintained a high sperm penetration rate (P<0.05). Interestingly, induction of the AR by treatment of preincubated sperm with progesterone was blocked by TA and GA as a result of their higher levels of ROS scavenging activity, while EA, which possessed weak ROS scavenging activity, did not disturb induction of the AR with progesterone. However, the incidence of AR induced by sperm-zona interaction was significantly decreased by the strong antihyaluronidase actions of TA and EA compared with that in the absence of these compounds. Treatment with the compounds caused neither a protective proteolytic modification of the zona pellucida matrix before fertilization nor a reduction in acrosomal proteolytic activity or the number of zona-bound sperm. These findings suggest that the antihyaluronidase action of EA effectively prevents polyspermy by suppression of AR functionality induced by sperm-zona interaction and that hyaluronidase intervention is therefore required during porcine IVF.     

Fundamental studies on wood/cellulose-plastic composites: effects of composition and cellulose dimension on the properties of cellulose/PP composite

Although wood/cellulose-plastic composites (WPC) of low wood/cellulose content have been more accepted worldwide and are promoted as low-maintenance, high-durability building products, composites containing high wood/cellulose content are not yet developed on an industrial scale. In this study, flow properties, mechanical properties, and water absorption properties of the compounds of cellulose microfiber/polypropylene (PP) and maleic anhydride-grafted polypropylene (MAPP) were investigated to understand effects of the high cellulose content and the dimensions of the cellulose microfiber. The molding processes studied included compression, injection, and extrusion. It was found that fluidity is not only dependent on resin content but also on the dimension of the filler; fluidity of the compound declined with increased fiber length with the same resin content. Dispersion of the composite was monitored by charge-coupled device (CCD) microscope. Increasing the plastic content in the cellulose-plastic formulation improved the strength of mold in addition to the bond development between resin and filler, and the tangle of fibers. The processing mode affected the physicomechanical properties of the cellulosic plastic. Compression-molded samples exhibited the lowest modulus of rupture (MOR) and modulus of elasticity (MOE) and the highest water absorption, while samples that were injection-molded exhibited the highest MOR (70 MPa) and MOE (7 GPa) and low water absorption (2%).     

Oral λ-carrageenan intake alleviates skin symptoms in a hapten induced atopic dermatitis-like model

Lambda carrageenan is a widely used food additive. It has been shown that its oral intake induces suppression of T cell proliferation and antibody-mediated and cell-mediated immune response in experimental animals. In this study, we estimated the effect of oral ingestion of 0.001% λ-carrageenan on trinitrochlorobenzen-induced atopic dermatitis model mouse. Oral carrageenan ingestion alleviated ear swelling of hapten challenged mice and significantly suppressed mast cell hyperplasia in the topical skin. Serological analysis revealed that the treatment suppressed total IgE and antigen-specific IgG, and also suppressed both allergy driving cytokine interleukin-4 and counter-acting cytokine interferon-γ levels. It is suggested that the oral ingestion of λ-carrageenan may suppress the immunological response to the allergen and might be useful to treat atopic dermatitis.     

ST segment depression and ventricular fibrillation in a dog after contrast agent administration

An 11-year-old Toy Poodle underwent a computed tomography examination with contrast (iohexol) enhancement under anesthesia. Heart rate and R-wave amplitude on electrocardiogram (ECG) increased 2.5 min after iohexol administration, and end-tidal carbon dioxide decreased to 12 mmHg. A progressive ST segment depression was observed on ECG. Subsequently, the ECG waveform changed to ventricular fibrillation. However, spontaneous circulation returned following cardiopulmonary resuscitation. Myocardial ischemia or anaphylactic shock was suspected in the dog, which explains the ST segment depression observed on ECG. When performing radiological examinations with a contrast agent, the ECG waveform changes, such as an increase in heart rate, R-wave amplitude, or ST segment depression, should be carefully monitored. This might enable early detection of cardiac dysfunction and the ensuing cardiac arrest in dogs.     

Assessment of criteria for improvement in Theileria orientalis sergenti infection tolerance

We examined the relationships between calf productivity, anemia and Theileria orientalis sergenti infection from records of 109 Japanese shorthorn calves during a grazing period and we quantified the relative importance of the T. orientalis sergenti infection‐resistance criteria used. A decrease in average parasitemia (AvePara) and an increase in average packed cell volume (AvePCV) would cause a decrease in the number of drug treatments. An increase in AvePCV would decrease the number of drug treatments more efficiently than a decrease in AvePara. An increase in AvePCV would cause an increase in dairy gain, while a decrease in AvePara would cause a decrease in dairy gain. Therefore, an improvement in the capacity to control anemia development would improve T. orientalis sergenti infection resistance more efficiently than an improvement in the capacity to control parasitemia development.     

Comprehensive Analysis of Plant Gene Expression in Soybean Root Nodules at Different Growth Stages

Gene expression profiles in early (12 d after sowing, DAS), mature (35 DAS) and senescent (77 DAS) soybean ( Glycine max (L.) Merr. cv. Enrei) root nodules were analyzed using Lotus japonicus cDNA macroarray. The cDNA macroarray membranes contained 18,144 independent cDNAs of L. japonicus isolated from various organs. The membranes were hybridized to ³³P-labeled single-strand cDNAs transcribed from mRNA extracted from the soybean root nodules at three different growth stages. The results showed that over 75% of the cDNA clones gave a relative signal intensity (RSI) lower than 300, irrespective of the soybean growth stage. cDNA with an RSI value over 5,000 accounted for 2.1, 1.2 and 0.5% of the total cDNA clones at 12, 35 and 77 DAS, respectively. The highest RSI value was detected in a clone hybridized to putative pectinesterase (MWM097c10_r) at 12 DAS, while the RSI value of lycopene β-cyclase (MWL025d06_r) was the highest at 35 and 77 DAS. At 77 DAS, the percentage of transferase gene cDNA clones accounted for 20.5% of the total cDNA clones showing an RSI value over 500, a value clearly lower than that at 12 and 35 DAS. On the other hand, the percentage of hydrolase gene cDNA clones accounted for 45.2% at 77 DAS, a value around 1.5 times higher than that at 12 and 35 DAS. The chronological RSI profiles of individual cDNA clones were classified into nine patterns, and the profiles of the cDNA clones belonging to 15 homologous gene groups encoding enzymes of nitrogen and carbon metabolism, nodule specific proteins, enzymes of RNA and protein hydrolysis, and synthesis of jasmonic acid precursor were compared within and between groups. As a result, significant variations both within- and between-groups were revealed.