Interannual decrease in condition factor of the western sand lance Ammodytes japonicus in Japan in the last decade: Evidence for food‐limited decline of the catch

Annual catch of the western sand lance Ammodytes japonicus in the eastern Seto Inland Sea, Japan, has shown a decreasing trend since the 1990s. To examine whether food shortage was the main cause for the catch decrease, we investigated the condition factor of the age‐0 fish at the beginning of the estivation period (late July) in Harima‐Nada, eastern Seto Inland Sea, for 10 years from 2008 to 2017. The mean abundance of copepods as food for the age‐0 fish during the fish growth period (from February to June) around the estivation area was also determined. The condition factor showed a significant decrease, and values for 2011 and later years were mostly lower than the known minimum threshold (4.2) for maturation. In the recent 4 years from 2013 to 2016, the mean copepod abundance was much lower than values for the other years. The condition factor showed a significant positive correlation with the copepod abundance. These results indicate that decline of western sand lance catch after 1990 was caused mainly by food shortage.     

包膜尿素氮素的溶出特性研究

 【目的】研究包膜尿素（LP 30）氮素的溶出特性。【方法】采用土壤、纯水两种培养方式,在4种温度（10、15、20、25 ℃）条件下对不同培养时期氮素溶出率进行测定,利用具体的方法——The number of days transformed to standard temperature（DTS）,对自然温度条件下氮素的溶出率进行预测。【结果】培养试验表明,土壤和纯水两种培养方式对包膜尿素氮素溶出率的影响很小,不同温度对氮素溶出率的影响显著。分析表明,一级反应动力学模型可很好地描述包膜尿素氮素的溶出过程。氮素溶出速率随温度升高而加快,在10～25℃内,每升高5℃,速率常数约提高1倍左右。包膜尿素埋藏土壤后实测的氮素溶出率值与采用DTS法预测的氮素溶出率值之间无明显差异。【结论】包膜尿素（LP 30）氮素溶出率大小主要取决于温度的变化,DTS法能较准确地预测包膜尿素施入土壤后,自然温度条件下,任意天数的氮素溶出率。     

A ground-based hyperspectral imaging system for characterizing vegetation spectral features

A cropping system is usually characterized by continuous spatio-temporal vegetation variability. Vegetation variability can be detected by changes in several vegetation parameters defined according to purpose. Estimation of these vegetation parameters has been made possible by calculating various vegetation indices (VIs), usually by ratioing, differencing, ratioing differences and sums, or by forming linear combinations of spectral band data. Spectrometers or sensors have been used to acquire visible and infrared spectral properties of vegetation. This paper presents a ground-based hyperspectral imaging system for characterizing vegetation spectral features. The hyperspectral sensor used was a ground-based line sensor, ImSpector (V10-12-102), with a nominal spectral resolution of 1.5–2 nm and a wavelength range of 360–1010 nm. A graphical user interface (GUI) was developed in a MATLAB environment to aid in processing and analysis of acquired multidimensional spectral image data. Issues that arise when applying the imaging system to a particular field include acquiring hyperspectral images, selecting appropriate vegetation features or VIs, and quantifying the selected vegetation features or indices with the GUI developed. Vegetation features extracted by the proposed imaging system contribute not only to monitoring vegetation variability in crop systems, but also provide a potential source of relevant variables that can be used to estimate various vegetation parameters. A study that was set up to investigate the alternate bearing phenomenon of citrus trees illustrates the basic elements of the proposed approach.     

The banding patterns of normal canine chromosomes

The chromosomal banding patterns of canine normal chromosome were analyzed by G-, Q-, C- and N-banding techniques. The chromosomes of canine normal lymphocytes consisted of 38 acrocentric autosome pairs and X-, Y-metacentric sex chromosomes. Their G- and Q-banding patterns corresponded to the those reported by Manolache et al. in 1976. C-bands of chromosomes were found on the centromeric regions of the 7th, 26th, 34th, 35th, 37th and 38th pairs of chromosomes. In addition, N-bands whose location had not been confirmed until now were recognized on the telomitic regions of the 7th, 9th and 22nd pairs of chromosomes.     

Effects of zinc on intact and castrated cockerels

1. Fourteen‐week‐old intact and castrated cockerels (White Leghorn) were injected intramuscularly with zinc (100 μg/kg body weight) as zinc ammonium sulphate solution once daily for 4 weeks and the effects on testes, pituitary and adrenal glands investigated histologically.

2. In intact cocks zinc decreased testes weight significantly, inhibited spermatogenesis and disturbed testicular hormone production. There was an increase in pituitary gonadotrophic cell activity, perhaps an indication of feed‐back response to low concentration of testicular hormone. Cortical and medullary cells of the adrenal glands showed signs of activation.

3. No discernible effects of zinc injection on pituitary and adrenal cells of castrates were observed. This may reflect a decrease in pituitary and adrenal responsiveness to repeated stimulation with zinc.

4. The results indicate that the effectiveness of a given dose of zinc was dependent on the physiological condition of the cockerels and the effective site of zinc action was centred in the testes.     

Composition of culture medium influences zoosporogenesis and differentiation of <Emphasis Type="Italic">Aphanomyces cochlioides</Emphasis>

A modified medium was used to culture mycelium and produce a large quantity of zoospores of Aphanomyces cochlioides, a principal pathogen of damping-off disease of sugar beet and root rot disease of spinach. The semisolid medium consisted of 17 g corn meal agar (CMA) added with 4 g of yeast extract (YE) per liter of 50 mM phosphate buffer (pH 6.8–7.0). This medium supported the production of ca. 10⁶ zoospores ml⁻¹ in 6-day-old cultures, approximately 11-fold higher than the commonly used CMA (17 g CMA per liter of water, pH 6.0 ± 0.2). Although morphological characters of the zoospores produced from the hyphae grown on CMA and CMA + YE were almost similar, they contrasted their developmental strategy after encystment induced by mechanical agitation. Cystospores originating from the zoospores on CMA regenerated zoospores (>80%), while those from CMA + YE germinated (ca. 80%) and produced hyphae. Furthermore, 4–10% of the germinated cystospores on CMA + YE had double germ tubes. The soluble protein profiles of zoospores produced on CMA and on CMA + YE demonstrated that several proteins were either different or expressed differently. Our results suggest that the culture medium directly influences zoosporogenesis in A. cochlioides hyphae and the developmental strategy of the produced zoospores.     

Comparison of the behavior of skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares) and bigeye (T. obesus) tuna associated with drifting FADs in the equatorial central Pacific Ocean

We evaluated the behavior of skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares) and bigeye tuna (T. obesus) associated with drifting fish aggregating devices (FADs) in the equatorial central Pacific Ocean. A total of 30 skipjack [34.5–65.0 cm in fork length (FL)], 43 yellowfin (31.6–93.5 cm FL) and 32 bigeye tuna (33.5–85.5 cm FL) were tagged with coded transmitters and released near two drifting FADs. At one of the two FADs, we successfully monitored the behavior of all three species simultaneously. Several individuals remained around the same FAD for 10 or more days. Occasional excursions from the FAD were observed for all three species, some of which occurred concurrently for multiple individuals. The detection rate was higher during the daytime than the nighttime for all the species, and the detection rate for bigeye tuna was higher than for yellowfin or skipjack tuna. The swimming depth was deeper during the daytime than nighttime for all species. The fish usually remained shallower than 100 m, but occasionally dived to around 150 m or deeper, most often for bigeye and yellowfin tuna during the daytime. The swimming depth for skipjack tuna was shallower than that for bigeye and yellowfin tuna, although the difference was not large, and is probably not sufficient to allow the selective harvest of skipjack and yellowfin tuna by the purse seine fishery. From the detection rate of the signals, bigeye tuna is considered to be more vulnerable to the FAD sets than yellowfin and skipjack tuna.     

Oxidative stress and antioxidant responses in juvenile Brazilian flounder <Emphasis Type="Italic">Paralichthys orbignyanus</Emphasis> exposed to sublethal levels of nitrite

This study evaluated the effects of short-term exposure to sublethal levels of nitrite on oxidative stress parameters and histology of juvenile Brazilian flounder Paralichthys orbignyanus. An assessment of fish recovery was also performed. Fish were exposed to 0.08 (control), 5.72, 10.43, and 15.27 NO₂-N mg L^?1 for 10 days followed by the same recovery time. Gill, liver, and muscle samples were collected after 1, 5, and 10 days of exposure and after recovery for the measurement of antioxidant capacity against peroxyl radicals (ACAP), glutathione-S-transferase (GST) activity, content of non-protein (NPSH) and protein thiols (PSH), and lipid peroxidation levels by thiobarbituric acid-reactive substances (TBARS) content. Nitrite exposure induced alterations which compromised the overall antioxidant system (reduced ACAP and GST activity) and enhanced oxidative damage in lipids and proteins. Increases in GST activity and NPSH and PSH contents were also demonstrated. The recovery period allowed for resumption of basal levels for all (treatment 5.72 NO₂-N mg L^?1) or some of the evaluated parameters (other treatments). In conclusion, exposure to nitrite concentrations from 5.72 to 15.27 NO₂-N mg L^?1 induced oxidative stress and antioxidant responses in juvenile Brazilian flounder. The 10-day recovery period was sufficient for a complete resumption of basal physiological condition of fish exposed to concentrations of up to 5.72 NO₂-N mg L^?1.     

Effect of Fucoidan Extracted from Mozuku on Experimental Cartilaginous Tissue Injury

We investigated the effect of fucoidan, a sulfated polysaccharide, on acceleration of healing of experimental cartilage injury in a rabbit model. An injured cartilage model was surgically created by introduction of three holes, one in the articular cartilage of the medial trochlea and two in the trochlear sulcus of the distal femur. Rabbits in three experimental groups (F groups) were orally administered fucoidan of seven different molecular weights (8, 50, 146, 239, 330, 400, or 1000 kD) for 3 weeks by screening. Control (C group) rabbits were provided water ad libitum. After the experimental period, macroscopic examination showed that the degree of filling in the fucoidan group was higher than that in the C group. Histologically, the holes were filled by collagen fiber and fibroblasts in the C group, and by chondroblasts and fibroblasts in the F groups. Image analysis of Alcian blue- and safranin O-stained F-group specimens showed increased production of glycosaminoglycans (GAGs) and proteoglycans (PGs), respectively. Some injured holes were well repaired both macroscopically and microscopically and were filled with cartilage tissues; cartilage matrices such as PGs and GAGs were produced in groups F 50, F 146, and F 239. Thus, fucoidan administration enhanced morphologically healing of cartilage injury.     

Development of a CO2 gas analyzer for monitoring soil CO2 concentrations

Measurement of soil CO₂ concentrations is important for investigating the dynamics and diffusion of CO₂ in soil. In this study, we developed a small CO₂ analyzer for measuring in situ-soil CO₂ concentrations. The CO₂ analyzer consists of a module containing an infrared CO₂ gas sensor, a temperature sensor, and a relative humidity sensor. These sensors are installed in a protective box with an air vent, which is suitable for burying in the soil. The output response time of the CO₂ analyzer was 349 s, as evaluated from the phase lag after input of known CO₂ concentrations. This response time is short enough to measure soil CO₂ concentrations, because variations in concentration are slower than the response time of the analyzer. In a field test, we used the CO₂ analyzer to measure soil CO₂ concentrations at five depths (0–50 cm) over 2.5 months. While the CO₂ concentration generally increased with depth, the amplitude of the variation in CO₂ concentration decreased with depth. The phase lag of the variations in soil CO₂ concentration also increased with depth, as did soil temperature. The tests confirm that the CO₂ analyzer is applicable to continuous monitoring of soil CO₂ concentrations.