黑鳅土水分特征及其形成原因分析

黑鳅土是三江平原的主要土壤类型之一。面积约1100万亩。大部分已垦为耕地,但在旱涝灾害的影响下,粮食产量一直不高不稳,且波动幅度大。本文根据在黑鳅土上长期的水分定位测定资料,对其水分动态规律及其形成原因作一分析,供改土治水中参考。

A Comparative Study on the Nonspecific Immunity of Juvenile Litopenaeus vannamei ever Inhabiting Freshwater and Seawater

A study on the nonspecific immunity of Litopenaeus vannamei ever inhabiting freshwater and seawater was carried out at different molt stages by comparing their total hemocyte count(THC) and respiratory burst(RB) and activity of phenol oxidase(PO), nitric oxide synthase(NOS) and lysozyme(LY). Two-way ANOVA showed that salinity and molt stage independently affected THC and RB and the activity of PO, NOS and LY of juvenile L. vannamei significantly(P < 0.05). The THC and RB and the activity of NOS gradually increased from the post-molt stages(A and B) to the pre-molt stages(D0–D3), which were common in shrimps inhabiting freshwater and seawater. The activity of PO peaked at the inter-molt stage(C), and touched the lowest at the post-molt stage in freshwater and pre-molt stage in seawater. The activity of LY was stable over the molt cycle. The RB and the activity of PO, NOS and LY of juvenile L. vannamei were significantly lower in freshwater than in seawater; whereas THC was significantly higher in freshwater than in seawater(P < 0.05). It was concluded that the post-molt stage(especially stage A) was critical to shrimp culture, which should be intensively attended when L. vannamei was cultured in freshwater.

Changes in growth and osmoregulation during acclimation to saltwater in juvenile Amur sturgeon Acipenser schrenckii

We evaluated the ability of juvenile Amur sturgeon (Acipenser schrenckii) to osmoregulate and grow in saltwater. Hatchery-reared juveniles (mean weight 106.8 g, 5-month old) were transferred from freshwater to 10, 20, and 25 salinity saltwater over a period of 20 d. We measured the growth, serum osmolality, ion concentrations, and Na+/K+-ATPase activity. In addition, we prepared samples of gill tissue to quantify morphological changes in gill ultrastructure. Rearing in up to 25 saltwater for 30 d had no significant effect on growth. Similarly, serum osmolality and ion concentrations were similar to levels reported in other teleosts following acclimation to saltwater. Serum osmolality and Na+, Cl- concentrations increased significantly with the initial increase in salinity. Afterwards, levels tended to stabilize and then decrease. Serum K+ levels did not change during acclimation to saltwater. Gill Na+/K+-ATPase activity increased initially as salinity was increased. However, the activity later decreased and, finally stabilized at 3.7±0.1 μmol Pi/mg·prot·h in 25 saltwater (1.6 times higher than the level in those in freshwater). In fish that were held only in freshwater, the chloride cells were located in the interlamellar regions of the filament and at the base of the lamella. Following acclimation to 25 saltwater for 30 d, the number and size of chloride cells increased significantly. Our results suggest that juvenile Amur sturgeon is able to tolerate, and grow in, relatively high concentrations of saltwater.

The eco-nutrition requirements for dietary protein and its rhomb characteristics in juvenile turbot (Scophthalmus maximus L.)

We evaluated the dietary protein requirements of juvenile turbot (Scophthalmus maximus L.) and their effects on aquatic quality. Five experimental diets were formulated containing 450, 480, 500, 520, and 540 g/kg. Each diet was randomly assigned to triplicate groups of juvenile turbot (mean initial body weight 34.5 ± 5.5 g) for 88 d. Both the weight gain ratio and feed efficiency increased with increasing dietary protein up to 500 g/kg, but no further improvement was detected when dietary protein levels were >500 g/kg. Protein intake and digestion increased with protein levels, while fecal nitrogen and nitrogen content in seawater increased only when dietary protein exceeded 500 g/kg. Protein digestibility was highest at intermediate dietary protein levels. Chemical oxygen demand, nitrite-nitrogen (NO2--N) and phosphatic-phosphor (PO43--P) levels increased in the rearing water as dietary protein levels increased. The optimum eco-nutrition level of dietary protein for juvenile turbot was 500 g/kg under the current experimental conditions. The diets containing 540 and 500 g/kg protein had similar growth rates and feed conversion ratios, but levels of ammonia (NH4+) and nitrogen were considerably higher in the water and feces, respectively, at the higher level of dietary protein. The difference in the pattern of change between body weight gain and ammonia concentration in water with increasing dietary protein is described by rhomb characteristics.

Effects of Dietary Stachyose on Growth Performance, Digestive Enzyme Activities and Intestinal Morphology of Juvenile Turbot(Scophthalmus maximus L)

A 12-week feeding trial was conducted to evaluate the effects of dietary stachyose on the growth performance, digestive enzymes activities and intestinal structures of juvenile turbot(Scophthalmus maximus L). Five isonitrogenous(49.58% crude protein) and isolipidic(10.50% crude lipid) diets were formulated to contain 0(Control), 0.625%(S-0.625), 1.25%(S-1.25), 2.5%(S-2.5) and 5%(S-5) stachyose, respectively. With the increase of stachyose level, the growth performance and feed utilization of turbot, such as the specific growth rate, final mean body weight, weight gain rate and feed efficiency, increased significantly(P < 0.05) and then stabilized. The feed intake of fish fed S-5 was significantly higher(P < 0.05) than that of fish in other groups. The activities of trypsin, intestinal caseinolytic, stomach and intestinal amylase were significantly influenced by stachyose(P < 0.05). The highest values of trypsin and intestinal caseinolytic activities were observed in group S-1.25, while the highest activity of stomach amylase and the lowest activity of intestine amylase were observed in group S-5. No lesion or damage was found on the distal intestine structures of fish from all treatments, while the height of simple folds in the distal intestine was significantly increased(P< 0.05) when 1.25% or 2.5% stachyose was added in the diets. These results indicated that moderate level of stachyose(1.25%) improves the growth performance, feed utilization, digestive enzyme activities and the distal intestine structures of juvenile turbot.

Growth and Feed Efficiency of Juvenile Shrimp Litopenaeus vannamei Fed Formulated Diets Containing Different Levels of Poultry by-Product Meal

This feeding trial was conducted to evaluate the potential of poultry by-product meal (PBM) as a protein source in the culture of Litopenaeus vannamei. Seven isonitrogenous and isoenergetic diets were formulated to near to commercial diet with about 40% protein and 7.5% lipid. Fish meal was replaced by 0, 30%, 40%, 50%, 60%, 70% and 100% of PBM (diets 1-7). The diet with 100% fish meal was used as a control (diet 1). Post-larvae were reared in an indoor semi-closed re-circulating system. Each dietary treatment was tested in 4 replicate tanks (260 L) of 40 shrimp, arranged in a completely randomized design. The shrimps were hand-fed for three times a day to near-satiation (0700, 1200 and 1800) for 60 d. Percentage weight gain, survival, feed conversion ratio (FCR), protein efficiency ratio (PER) and body composition of shrimps were measured. There were no significant differences (P>0.05) in growth performance among shrimps fed diets 1-5 (0-60% fish meal replacement). However, shrimps fed diet 7 (100% fish meal replacement) had significantly lower (P<0.05) growth than those fed diets 1-5 (0-60% fish meal replacement). Shrimp fed diets 2-4 (30%-50% fish meal replacement) showed significantly higher growth than those fed diets 6 and 7 (70% and 100% fish meal replacement, respectively). Survival ranged from 94.7% to 100.0% and did not differ significantly (P>0.05) among different experimental diets. No differences in body composition were found among shrimps fed different diets. These results showed that up to 70% of fish meal protein can be replaced by PBM without adversely affecting the growth, survival, FCR, PER and body composition of Litopenaeus vannamei.

Growth and energy budget of juvenile lenok Brachymystax lenok in relation to ration level

We evaluated the effect of ration level （RL） on the growth and energy budget of lenok Brachymystax lenok. Juvenile lenok （initial mean body weight 3.06±0.13 g） were fed for 21 d at five different ration levels： starvation, 2%, 3%, 4% bwd （body weight per day, based on initial mean values）, and apparent satiation. Feed consumption, apparent digestibility, and growth were directly measured. Specific growth rates in terms of wet weight, dry weight, protein, and energy increased logarithmically with an increase in ration levels. The relationship between specific growth rate in terms of wet weight （SGRw, %/d） and RL （%） was characterized by a decelerating curve： SGRw=- 1.417＋3.1661n（RL＋ 1）. The apparent digestibility coefficients of energy exhibited a decreasing pattern with increasing ration level, and there was a significant difference among different RLs. Body composition was significantly affected by ration size. The relationship between feed efficiency rate in terms of energy （FERe） and RL was： FERe=- 14.167＋23.793RL-3.367（RL）2, and the maximum FERe was observed at a 3.53% ration. The maintenance requirement for energy of juvenile lenok was 105.39 kJ BW （kg）-0.80/d, the utilization efficiency of DE for growth was 0.496. The energy budget equation at satiation was： 100IE=29.03FE＋5.78（ZE＋UE）＋39.56 HE＋25.63 RE, where IE is feed energy, FE is fecal energy, ZE＋UE is excretory energy, HE is heat production, and RE is recovered energy. Our results suggest that the most suitable feeding rate for juvenile lenok aquaculture for wet weight growth is 2.89% bwd, whereas for energy growth, the suggested rate is 3.53% bwd at this growth stage.

Effects of waterborne Fe(Ⅱ) on juvenile turbot Scophthalmus maximus:analysis of respiratory rate,hematology and gill histology

The concentration of Fe（II） is high in some groundwater supplies used in turbot culture, and the toxicity of waterborne Fe（II） is unknown. We investigated the stress responses of juvenile turbot, Scophthalmus maximus, exposed to Fe（II） of different concentrations （0.01, 0.05, 0.1, 0.5, 1, and 2 mg/L） for 1, 7, 14, and 28 d, under the same ambient conditions of other parameters. Changes in respiratory rate, hematological parameters, and gill structure were determined. The results show that waterborne Fe（II） did not cause severe hematological perturbation to turbot. A low-medium Fe（II） concentration （lower than 0.1 mg/L） could boost the respiratory rate, and caused no or very limited damage to fish. A high Fe（II） concentration （0.1 mg/L or higher）, however, caused gill damage, such as vacuoles in branchial lamellae, epithelial necrosis, and hypertrophy of epithelial cells, and even death after extended exposure time. Therefore, excess waterborne Fe（II） and long-term exposure to Fe（II） could be responsible for poor growth and high mortality of turbot in culture. The concentration of waterborne Fe（II） in turbot culture should be kept below 0.1 mg/L.

Effects of Dietary Soy Isoflavones on Feed Intake,Growth Performance and Digestibility in Juvenile Japanese Flounder(Paralichthys olivaceus)

An 8-week feeding trial was conducted to investigate the effects of dietary soy isoflavones on feeding intake,growth performance,and digestion of juvenile Japanese flounder(Paralichthys olivaceus).Four isonitrogenous(49% crude protein) and isoenergetic(20.1 MJ kg-1) diets were formulated to contain four graded levels of soy isoflavones,namely,0,1,4 and 8 g soy isoflavones in 1 kg of diet.Each diet was randomly fed to triplicate tanks of fish(Initial average weight:2.58 g ± 0.01 g),and each tank was stocked with 35 fish.No significant difference was observed among diets with levels of 0,1 and 4 g kg-1 soy isoflavones in feed intake,weight gain,feed efficiency ratio(FER),proximate composition of fish whole body and apparent digestibility coefficients(ADC) of nutrients and energy(P>0.05).However,high dietary soy isoflavones level(8 g kg-1) significantly depressed weight gain,FER,whole-body crude lipid content of fish and ADC of nutrients(P<0.05).These results indicate that high level of dietary soy isoflavones(above 4 g kg-1) significantly depresses growth responses and FER of Japanese flounder.However,as the content of soy isoflavones in soybean meal is around 1 to 3 g kg-1,the adverse effects might be neglected when soybean products are used as a fish feed ingredient.

Changes during late-stage embryonic development from egg-juvenile to free-living hatchling in Chinese freshwater crab Sinopotamon yangtsekiense (Decapoda, Brachyura, Potamidae)

This study expands on recent reports that direct development in the Chinese potamid freshwater crab Sinopotamon yangtsekiense involves the completion of all brachyuran larval stages (nauplius, zoea, and megalopa) inside the egg case during embryonic development. Detailed studies of embryonic development in this species revealed the presence of an additional larval stage (the egg-juvenile) between the megalopa and the free-living hatchling crab. We described and compared the appendages of the head, thorax, and abdomen of the egg-juvenile with those of the hatchling crab in S. yangtsekiense. Significant differences were found between most of the appendages of these two stages with a soft exoskeleton in the egg-juvenile, no joint articulation, a slimmer appearance, and a lack of setae when compared with the newly emerged free-living hatchling crab. These modifications of the appendages are related to the confinement within the egg case of the egg-megalopa and egg-juvenile during direct development, and the need for the free-living hatchling freshwater crab to move, feed, and respire. In marine crabs, the megalopa gives rise to the first crab stage whereas in freshwater crabs the egg-juvenile follows the megalopa and immediately precedes the free-living first crab stage.

Contribution of El Nino amplitude change to tropical Pacific precipitation decline in the late 1990s

Equatorial central Pacific precipitation experienced a prominent decline in the late 1990 s.This change was previously attributed to a La Nina-like mean sea surface temperature(SST)change in the Pacific Ocean associated with a phase switch of the Interdecadal Pacific Oscillation.Here,using a series of model experiments,the authors reveal that the El Nino-related interannual SST anomalies contributed largely to the precipitation decrease over the equatorial central Pacific.This El Nino SST effect was due to the change in the amplitude of El Nino events in the late 1990 s.The 1980-98 decade had more large-amplitude El Nino events than the 1999-2014 decade.The nonlinear precipitation response to SST anomalies resulted in a larger decadal mean precipitation in the 1980-98 decade than in the 1999-2014 decade.The results highlight the importance of El Nino amplitude change in future climate change related to global warming.

Iron and Zinc Serum Levels in Young Adult Cameroonians after Supplementation in Poor Vitamin A and Controlled Diets

Iron, zinc and vitamin A deficiencies co-exist in Cameroon in all age groups. However, natural sources of vitamin A are available and could be used to meet the need of the whole population in association with iron and zinc supplementation. This study aims at assessing the serum levels of zinc and iron after 11 days of supplementation. The study enrolled 26 men 08-33 years）, distributed into five groups. From the first day, they were supplemented with 20 mg of zinc and iron, taken each alone, both either together or at two different times. The five last days, participants were put on free vitamin A diets. Serums were obtained at day l, day 5 and day 11 for Zn and Fe levels determination by atomic absorption spectrophotometry. The highest serum iron and zinc concentrations were observed in groups either supplemented with zinc or with iron given alone. In those two groups, serum Zn concentrations increased from 0.69 μg/mL ±0.02μg/mL to 0.95 μg/mL ± 0.13 μg/mL （group 2）, from 0.48 μg/mL ± 0.06 μg/mL to 0.97 μg/mL ± 0.11 μg/mL （group 3）; and serum Fe concentrations from 1.49 μg/mL ± 0.54 μg/mL to 3.49 μg/mL ± 1.01 μg/mL （group 2）; and from 1.42 μg/mL ± 0.45 μg/mL to 3.41 μg/mL ± 0.81 μg/mL （group 3）, respectively. Supplementation with Fe or Zn alone increased both Fe and Zn serum levels of participants. Serum levels of iron and zinc when given together or at different time were not significantly different. Further studies on a larger population are necessary to confirm that supplementation with zinc or with iron alone could raise both zinc and iron levels in serum simultaneously.

Profiling and Comparison of Color Body Wall Transcriptome of Normal Juvenile Sea Cucumber(Apostichopus japonicus) and Those Produced by Crossing Albino

Sea cucumber(Apostichopus japonicus) is one of the most important aquaculture animals in China. Usually its normal body color is black that fits its living environment. The juvenile individuals obtained by crossing albino sea cucumber segregated in body color. To document the transcriptome difference between albino associating sea cucumber and the control, we sequenced their transcriptomes with RNA-seq. Approximately, 4.790 million(M) and 4.884 M reads, 200 nt in length, were generated from the body wall of albino associating sea cucumber and the control, respectively, from them, 9550(46.81%) putative genes were identified. In total, 583 genes were found to express differentially between albino associating sea cucumber and the control. Of these differentially expressed genes(DEGs), 4.8% changed more than five-folds. The expression levels of eight DEGs were confirmed with real-time PCR. The changing trend of these DEGs detected with real-time PCR agreed well with that detected with RNA-seq, although the change degree of some DEGs was different. Four significantly enriched pathways were identified for DEGs, which included phagocytosis, Staphylococcus aureus infection, ECM-receptor interaction and focal adhesion. These pathways were helpful for understanding the physiological difference between albino associating sea cucumber and the control.

Access to Reproductive Health Services for Adolescents in the Educational System, Phetchaburi Province

This study was based on a descriptive research design. The population comprised of males and females aged between 15 and 19 years studying at the high school, college, and university levels in Phetchaburi, Thailand. The sample group size was calculated by using Taro Yamane＇s formula at a reliability level of .95. The instrument used was the questionnaire of College of Public Health as modified by Chulalongkorn University for use in research. Instrument quality was calculated by using the Kuder-Richardson 20 formula; an internal consistency value of.86 was obtained. According to the findings, the comparison of access to reproductive health services by adolescents at each level of education, the educational levels of the adolescents were similar to one another in that they were found to have received instruction about sexuality and reproductive health. The instruction most frequently received was on reproductive health and the least frequent subject was life skills, ability to adjust to daily lifestyles. The findings suggested that the capacity of medical and academic personnel should be developed in order to gain knowledge, attitudes to provide reproductive health services, especially on subjects concerning life skills and ability to adjust to daily life and interacting with the people surrounding adolescents, including skills on how to refuse sexual activity with partners.

水危机困扰京津冀

刘继东今年夏天特意去了趟济南,本意是想到"泉城"避避暑气,没想到长时期的酷暑高温早就使"泉城"变成了"旱城",就连饮水还要定时供应.不过比起去承德避暑的邻居来,他还是满庆幸的.热河那边旱得都没水了,热得就跟火焰山似的.他说:"还是北京好,什么时候也缺不了你用水".虽说水费是涨了,但北京的市民在这个大旱的夏天,却还真没有感到过缺水的威胁.河北北部今年遭受的百年不遇的大旱,仿佛就跟今夏的暑气一样,被北京人关在了门外. ……

Disturbance cues in freshwater prey fishes： Does urea function as an ＇early warning cue＇ in juvenile convict cichlids and rainbow trout？

Freshwater vertebrate and invertebrate prey species commonly rely on chemosensory information, including non-injury released disturbance cues, to assess local predation threats. We conducted laboratory studies to （1） determine if urea can function as a disturbance cue in juvenile convict cichlids and rainbow trout and （2） determine if the background level of urea influences the behavioral response to a subsequent pulse of urea （＇background noise＇ hypothesis）. In the first series of trials, juve- nile cichlids and trout were exposed to urea at varying concentrations （0 to 0.5 mg L-1 for cichlids and 0 to 1.0 mg L1 for trout）. Our results suggest that both cichilds and trout exhibited functionally similar responses to urea and conspecific disturbance cues and that increasing the concentration of urea results in an increase intensity of antipredator behaviour. In the second series of trials, we pre-exposed cichlids or trout to intermediate or high concentrations of urea （or a distilled water control） and then tested for the response to a second pulse of urea at at intermediate or high concentrations （versus a distilled water control）. Our results demon- strate that pre-exposure to urea reduces or eliminates the response to a second pulse of urea, supporting the background noise hy- pothesis. Together, our results suggest that pulses of urea, released by disturbed or stressed individuals, may function as an early warning signal in freshwater prey species

MODELING BINGE DRINKING

We develop a two-stage （four component） model for youths with serious drinking prob- lems and their treatment. The youths with alcohol problems are split into two classes, namely those who admit to having a problem and those who do not. It is shown that the model possesses two steady states, one where people have no alcohol problems and one where there is an endemic state involving those with an alcohol problem. The stability of these states is analyzed and a threshold established such that each state will be stable depending on whether the incidence rate is above or below the threshold. The model is analyzed in the context of actual data.