Reproduction in the protogynous black grouper Mexico (Mycteroperca bonaci (Poey)) from the southern Gulf of Mexico

An analysis was made of sexual pattern, spawning season, sizes at sexual maturation, and sex change in black grouper (Mycteroperca bonaci) from the southern Gulf of Mexico. Samples were taken between 1996 and 2000, from industrial and small-craft commercial fi sheries, in offshore and inshore waters of the continental shelf of the Yucatan Peninsula (Campeche Bank), including the shallow waters of National Marine Park Alacranes Reef. For all collected specimens (n=1229), sex and maturation condition were determined by histological analysis of the gonads. The offshore sample consisted of 75.1% females, 24.3% males, and 0.6% transitional-stage fish. All individuals collected from inshore waters were females. Gonadal structure and population structure characteristics for Campeche Bank black grouper were consistent with the characteristics of monandric protogynous hermaphrodism for a serranid fish. Sexually active males and females were observed year-round, although ripening females, with stage-III, -IV, and -V vitellogenic oocytes in the ovaries, dominated in samples taken between December and March. In addition, peak occurrence of ripe-running females with hyaline oocytes or postovulatory follicles (or both) in the ovaries was recorded in January and February. A few precocious females began spawning in October and November, and others were still in spawning condition in May and June. Fifty percent maturity of females was attained at 72.1 cm fork length (FL). Median size at sexual inversion was 103.3 cm FL, and 50% of the females measuring 111.4 cm FL had transformed into males. The southern Gulf of Mexico grouper fishery was considered deteriorated and lacked a well-defined management strategy. Results of the present study provide helpful information on black grouper reproduction in this area and could help Mexican authorities choose appropriate management strategies for this fishery, such as minimum size limit, closed fishing season, and protection of spawning aggregations.

Effect of salt on the level of histamine in preserved fish (Herring, Clupea harengus)

Histamine levels in batches of heavily salted (fish:salt ratio 4:1) herring (Clupea harengus) were monitored during ripening at 4°C and 25°C. The batches studied were prepared from both pre-spawning and post-spawning (spent) fish using new and used salt. Salt levels in the flesh, which reached 11 to 14% (wet weight basis) during the ripening period, were found to retard histamine formation. During normal spoilage of ice chilled fish, histamine levels had been reported to exceed 50mg/100g flesh as it approached the limit of edibility whilst, in the heavily salted fish, levels remained below 20mg/100g flesh throughout the ripening periods of 18 months for the 4°C batches and 3 months for the 25°C batches. This was the case when the samples were set up and the salt allowed penetrating the flesh at 4°C. When, however, the samples were set up and initially stored at ambient (10-15°C) temperature the histamine levels in the flesh rose above 20mg/100g before enough salt had penetrated to inhibit its generation. The gradual rise in levels which, nevertheless, occurred over the ripening periods followed significantly (5% level of significance) different trends, being greater in the batches prepared from pre-spawning than those from spent fish.

两种完熟相关基因反义RNA在转因番茄中的表达及其对果实完熟的仰制作用

植物激素乙烯作为一种信使分子调节控制果实完熟。ACC合成酶是植物体内乙烯生物合成途径的限速酶，其反义RNA的表达将能有效地抑制乙烯的生物合成而延缓果实完熟，利用反转录PCR技术克隆获得了ACC合成酶多基因家族成员之一LE-ACC2阅读框架约1.7kb的cDNA，经酶切图谱和序列分析鉴定无误后，反向连入植物表达载体pBin437中构建成组成型表达ACC合成酶反义RNA的双元载体。经农杆菌途径转化番茄“丽春”品种，获得了60株抗卡那再生杭株，PCR检测证明有6株为转基因植株，Southern杂交和Northern杂交分析进一步确证了外源基因的插入及其转录活性。反义番茄果实的乙烯释放受到明显抑制，表现出更好的耐储保鲜特性，并且与对照相比，在果实品质上没有明显差别。大田培育Fl和F2代转化番茄植株，反义番茄纯合品系的筛选工作正在进行之中。 同时，本研究利用已经获得的ACC合成酶和PG的cDNA克隆，构建了两个嵌合转化基因载体pPGACC1、pPGACC10，它包括1300bp的ACC合成酶cDNA编码序列，并分别含有反向与正向的250bp的5’端PG基因片断。酶切图谱和序列分析鉴定无误后，以pBin437为植物表达载体构建了双元载体pBPGACC1和pBPGACC10，分别表达PG正义RNA和反义RNA，并均表达ACC合成酶反义RNA。经农杆菌转化番茄子叶，植株的再生培育有待进行。通过对转基因植物的分析，我们期望阐明用单一嵌合基因表达载体通过反义抑制与抑制作用实现对内源两同源基因——PG和ACC合成酶下降调节的可能性，并可望得到具有更好耐储效果且品质优良的番茄品系。

葡萄浆果成熟与延迟采收期间糖酸变化特点的研究

连续2年对“京秀”ד亚历山大”（编号97-2）杂交后代10个单株和“京秀”ד香妃”（编号97-3）杂交后代10个单株成熟期和延迟采收期的糖酸组分含量进行测定，以了解葡萄浆果延迟采收内在品质的变化差异。第二年 对可长期挂果的亲本“京秀”、“亚历山大”和杂交后代单株“97-2-23”、“97-2-24”成熟期和延迟采收期糖酸组分动态变化进行测定，以了解葡萄浆果糖酸品质延迟采收期的动态变化规律。同时对以上四个单株的浆果中蔗糖代谢相关酶活性和浆果呼吸强度进行测定，以对不同蔗糖表现型的产生原因进行探讨。研究表明： 葡萄延迟采收，浆果内可溶性糖变化可分为积累型和稳定型两种类型。延迟采收3周，糖积累型的8个单株浆果 可溶性糖显著积累，而稳定型的12个单株的糖与成熟时不存在显著差异。浆果主要积累果糖和葡萄糖，这两种糖的 动态变化趋势基本一致，但果糖变化幅度较大。两种类型的有机酸含量在延迟采收期间变化不大，没有显著差异。 糖积累型的“京秀”和“97-2-23”延迟采收期间各蔗糖分解酶（酸性转化酶、中性转化酶、蔗糖合成酶分解方 向）活性持续升高，但糖稳定型的“亚历山大”和“97-2-24”延迟采收第3周时急剧降低。此外，果实成熟和延迟 采收期间两种糖表现型浆果的呼吸速率也存在差异。浆果的蔗糖分解酶活性和呼吸速率存在的差异可能是两种类型 延迟采收期间糖含量存在差异的重要原因。

Physiological and biochemical study of over-ripened oocyte in the cultivated Caspian brown trout (Salmo trutta caspius) and determination of egg quality markers

To determine the best time for egg stripping after ovulation and over-ripened oocyte in the Caspian brown trout (Salmo trutta caspius), the eggs were retained in the parental abdominal cavity for 40 days post-ovulation (DPO) at 7±0.6°C. Eggs were stripped every 10-day interval in 4 treatment and were fertilized with a pool of semen obtained from 8 males. Also, the physiology and biochemistry of the eggs and ovarian fluids were studied. Results showed that the level of eyed eggs and hatched alevins declined with over-ripening time: that is, the expected amounts (90.65 ± 6.28% for eyeing and 86.33 ± 6.82% for hatching) in newly ovulated eggs (0–10 DPO) decreased to 0.67 ± 1.34% and 0.49 ± 0.98%, respectively, in over-ripened eggs (30–40 DPO). However, larval abnormalities remained constant for 30-days after ovulation. During the course of oocyte over-ripening, the pH of the ovarian fluid significantly decreased and the concentration of glucose, protein, calcium, iron, and aspartate aminotransferase activity significantly increased. Moreover, the concentration of protein, triglycerides, and aspartate aminotransferase activity in the eggs also changed. In the newly ovulated egg, the yolk consisted of homogenous tissue and its perivitelline space diameter had no considerable differences. With over-ripening, the yolk became heterogeneous, while chorion diameter and micropyle did not change. The perivitelline space diameter varied among different areas. The present study demonstrated that the best time to take Caspian brown trout eggs after ovulation at 7± 0.6°C was up to 10 DPO. Among the studied parameters of the egg and ovarian fluid, egg quality was related to both ovarian fluid parameters (e.g., pH, protein, aspartate aminotransferase, glucose, cholesterol, triglycerides, calcium, iron) and egg parameters (e.g., cholesterol, triglycerides, iron, aspartate aminotransferase). Thus, these parameters can be used as a egg quality markers in this species.

Contribución al estudio biológico de Loligo brasiliensis Bl

A total of 592 individuals of Loligo brasiliensis from the Mar del Plata coastal fishing area (Buenos Aires prov., Argentina) have been studied during the 1961-1964 period. From a morphological point of view the population appears to be uniform and homogeneus. A brief description of this species is given in this paper since references in the literature are scarce from the time at which Blainville (1923) first described it. The only further references are found in D'Orbigny (1835), and Ferrusac (1839), and in Hoyle (1886), and Tyron Pilsbry (1879). In this paper the species was mentioned only as a bibliographical reference on morphological or biological conditions has been found in the literature. The distribution of this species ranges from Cuba, Brazil, Uruguay to the Argentine coast, probably down to the Gulf of San Jorge. The samples had been studied with respect to various body measurements by classifing the individuals in total length classes, since body length was considered the most significant measurement. The condition factor K has been calculated for different sexes and ages, for the various length classes. The results lead to the conclusion that the smaller the length the higher is the value obtained for K and viceversa. This is due to the fact that the length of the tentacle increases considerably with increasing size. Since the tentacle are quite light the factor K diminishes accordingly. The condition factor increases considerably from December to April with an average of 0.42, decrease and becomes stable from March to October, with an average of 0.30. This is a consequence of the ripening of the sex glands. The sex-ratios are as following: year 1961, 42 % female, 42 % male; year 1962, 51 % female, 45 % male; year 1963, 46 % female, 53 % male; year 1964, 26 % female, 42 % male, 32 % indif. The great percentage of 72 undifferentiated young individuals in the 1964 (March) sampling increases the ratio of undifferentiation. A short morphological description of both ovules and spermatozoos is given. An examination of the sex glands leads to the following conclusions: a) male and female sex gland in a preparatory stage during the whole year; b) the highest percentage of ripe glands is found through, November-March; e) the spawning appears to precede rather slowly, but this certain since the spawning environment does not coincide with the natural habitat of the species. Few spawning individuals were found; d) sexual differentiation begins at body lenght from 30 to 40 mm; i.e. a total length of approximately 145 mm. At a body length of 70 mm. the hectocotilication (sexual character) begins to appear. In June 1962, a sample gathered at Rawson (Chubut) was analyzed. The conclusion was reached that the sex glands in this population are in an earlier stage of development in comparison with those from the Mar del Plata area. Also the average for the factor K which were found to be 0.17 for females and 0.19 for male, are rather low for that date. These physiological facts are possibly related to morphological differences which will be pointed out in a forthcoming publication. Some very typical associations with Artemesia longinaris and Percophis brasiliensis were found. Cannibalism has been observed.

Evolution of wetting layer of InAs/GaAs quantum dots studied by reflectance difference spectroscopy

For the InAs/GaAs quantum-dot system, the evolution of the wetting layer (WL) with the InAs deposition thickness has been studied by reflectance difference spectroscopy (RDS) in combination with atomic force microscopy and photoluminescence. One transition related to the light hole in the WL has been observed clearly in RDS, from which its transition energy and in-plane optical anisotropy (OA) are determined. The evolution of WL with the InAs dot formation and ripening has been discussed. In addition, the remarkable changes in OA at the onsets of the dot formation and ripening have been observed, implying the mode transitions of atom transport between the WL and the dots.

聚甲基丙烯酸甲酯／苯乙烯一丙烯腈共聚物混合体系相分离问题

本工作从实验和理论上探讨了高分子混合体系不稳相分离动力学机理。用光散射和固体核磁技术研究了苯乙烯一丙烯腈共聚物和聚甲基丙烯酸甲酯混合体系相分离过程。证实了Cahn-Hiuiand线理论适合与描述相分离早期过程；首次用激光散射方法在Cahn-Hiuiard线性理论基础上得到了相分离增长速率存在最大值R(9m)；同时阐明了界面目由能对R(q)的影响，澄清了文献多年的争议问题；在Cook线性理论框架中得到了虚结谱因子，探讨了热力对相分离初期的影响，从固体核磁实验中得到了该体系相分离初期相区浓度随相分离时间变化的趋势；探讨了相分离中后期散射峰强I_m，峰位q_m与时间t的标度行为以及结构函数的标度行为；光散射积分不变量表明在相分离后期发生了Q9+wald Ripening；在leibler和kawasaki理论基础上探讨了相分离动力学，得到了一个描述相分离动力学非缘性方程。

CO2浓度升高和氮肥管理对土壤线虫群落的影响

大气CO2浓度升高能够对农田生态系统产生一系列的影响。土壤线虫在农田生态系统腐屑食物网中占有重要的地位，能够对外界环境变化作出较迅速的响应。本文利用江苏省江都市小记镇的稻-麦轮作FACE系统研究平台，在2007-2008年小麦生长季，研究了大气CO2浓度升高和不同氮肥处理（高N和低N）对农田土壤线虫群落的影响。 研究结果表明：高氮肥施用情况下, CO2浓度升高显著降低了麦田土壤铵态氮和硝态氮含量。不同氮肥处理中CO2浓度升高条件下土壤可溶性碳的含量显著低于对照，而土壤总有机碳和微生物量碳含量高于对照。 大气CO2浓度升高条件下，麦田土壤线虫群落组成和多样性与对照相比表现出显著差异。CO2浓度升高显著增加了麦田土壤线虫总数、食细菌线虫、食真菌线虫和植物寄生线虫数量。在小麦拔节期和成熟期，低N和高N施用条件下，FACE处理中土壤线虫多样性指数（H’）、成熟度指数（MI和PPI）均低于对照处理，而结构指数（SI）高于对照处理。线虫生态指数的结果表明，大气CO2浓度升高条件下，土壤线虫群落多样性降低，土壤环境受到一定的干扰，食物网趋于结构化。

Formation of an fcc phase through a bcc metastable state in crystallization of charged colloidal particles

By in situ monitoring structural changes with the reflection spectrometer during the colloidal crystallization, we present direct experimental evidence of liquid-bcc-fcc phase transition in crystallization of charged colloidal particles, as a manifestation of the Ostwald's step rule. In addition, the lifetime of the bcc metastable structure in this system decreases significantly with increasing particle volume fraction, offering a possible explanation for "exceptions" to the step rule.

水肥空间组合对成熟期冬小麦各器官氮磷养分分配的影响

以肥熟土垫旱耕人为土为供试土壤,冬小麦(Triticum aestivum L.)小偃22为供试植物,在全生育期人工控制土壤水分条件下,采用分层隔水土柱法研究了与田间土层分布相同土柱不同土层水分、氮、磷组合对冬小麦不同器官氮、磷养分累积及分配的影响.结果表明:(1)冬小麦不同器官氮、磷累积量表现为籽粒茎秆、叶>穗余部>根系.(2)与整体湿润处理相比,上干下湿水分处理可降低小麦各器官氮、磷累积量,但仅籽粒氮、磷累积量所占比例减少,而营养器官氮累积量所占比例均增加.(3)从肥料处理看,单施氮、单施磷和氮磷配施处理的小麦植株各器官氮、磷累积量均比对照增加,但籽粒氮、磷累积量所占比例均减小.(4)施肥层根系氮、磷累积量比对照相对增加,并以0～30cm土层根系氮、磷累积量为最高.(5)单施氮条件下,以0～90cm土层施肥各器官氮、磷累积量最高,0～30cm土层施肥最低;单施磷和氮磷配施时,以0～90cm土层施肥处理籽粒氮、磷累积量最高,其次是0～30cm土层施肥.由于石灰性土壤中肥料氮终产物以硝态氮为主且容易移动,而磷肥不易在土壤中迁移,在生产实践中仍以氮磷配施入0～30cm土层为佳.

DYNAMIC SCALING OF THE STRUCTURE-FUNCTION FOR SPINODAL DECOMPOSITION IN CRITICAL AND NONCRITICAL MIXTURES OF POLY(VINYL ACETATE) POLY(METHYL METHACRYLATE)

The dynamics of phase separation in a binary polymer blend of poly(vinyl acetate) with poly(methyl methacrylate) was investigated by using a time-resolved light-scattering technique. In the later stages of spinodal decomposition, a simple dynamic scaling law was found for the scattering function S(q, t)(S(q, t) approximately I(q, t)): S(q, t)q(m)-3 S approximately (q/q(m)). The scaling function determined experimentally was in good agreement with that predicted by Furukawa, S approximately (X) approximately X2/(3 + X8) for critical concentration, and approximately in agreement with that predicted by Furukawa, S approximately (X) approximately X2/(3 + X6) for non-critical mixtures. The light-scattering invariant shows that the later stages of the spinodal decomposition were undergoing domain ripening.

Primary proteolysis of caseins in cheddar cheese

Studies were undertaken to investigate proteolysis of the caseins during the initial stages of maturation of Cheddar cheese. Isolated caseins were hydrolyzed by enzymes thought to be of importance during cheese ripening and the resulting peptides isolated and identified. Large peptides were also isolated from Cheddar cheese and identified, thus enabling the extent to which casein degradation studies could be extrapolated to cheese to be established. The proteolytic specificity of chymosin on bovine αs1- and αs2-caseins and of plasmin on bovine αs1-casein were determined. The action of cathepsin D, the principal indigenous acid milk proteinase, on caseins was studied and its pH optimum and sensitivity to NaCI determined. The action of cathepsin D on αs1-, αs2-, β- and κ-caseins was compared with that of chymosin and was found to be generally similar for the hydrolysis of αs1- and κ-caseins but to differ for αs2-and β- caseins. β-Casein in solution was hydrolyzed by cell wall-associated proteinases from three strains of Lactococcus lactis; comparison of electrophoretograms of the hydrolyzates with those of Cheddar cheese indicated that no peptides produced by cell wall-associated proteinases were detectable in the cheeses. All the major peptides in the water-insoluble fraction of Cheddar cheese were isolated and identified. It was found that β-casein was degraded primarily by plasmin and αs1 -casein by chymosin. Initial chymosin and plasmin cleavage sites in αs1-, and β-casein, respectively, identified in these and other studies corresponded to the peptides isolated from cheese. The importance of non-starter lactic acid bacteria (NSLAB) to the maturation of Cheddar was studied in cheeses manufactured from raw, pasteurized or microfiltered milks. NSLAB were found to strongly influence the quality and patterns of proteolysis. Results presented in this thesis are consistent with the hypothesis that primary proteolysis in Cheddar is catalysed primarily by the action of chymosin and plasmin on intact αs1- and β-caseins, respectively. The resulting large peptides so produced are subsequently degraded by these enzymes and by proteinases and peptidases from the starter and NSLAB.

Variations in total and differential milk somatic cell counts and plasmin levels and their role in proteolysis and quality of milk and cheese

Increased plasmin and plasminogen levels and elevated somatic cell counts (SCC) and polymorphonuclear leucocyte levels (PMN) were evident in late lactation milk. Compositional changes in these milks were associated with increased SCC. The quality of late lactation milks was related to nutritional status of herds, with milks from herds on a high plane of nutrition having composition and clotting properties similar to, or superior to, early-mid lactation milks. Nutritionally-deficient cows had elevated numbers of polymorphonuclear leucocytes (PMNs) in their milk, elevated plasmin levels and increased overall proteolytic activity. The dominant effect of plasmin on proteolysis in milks of low SCC was established. When present in elevated numbers, somatic cells and PMNs in particular had a more significant influence on the proteolysis of both raw and pasteurised milks than plasmin. PMN protease action on the caseins showed proteolysis products of two specific enzymes, cathepsin B and elastase, which were also shown in high SCC milk. Crude extracts of somatic cells had a high specificity on αs1-casein. Cheeses made from late lactation milks had increased breakdown of αs1-casein, suggestive of the action of somatic cell proteinases, which may be linked to textural defects in cheese. Late lactation cheeses also showed decreased production of small peptides and amino acids, the reason for which is unknown. Plasmin, which is elevated in activity in late lactation milk, accelerated the ripening of Gouda-type cheese, but was not associated with defects of texture or flavour. The retention of somatic cell enzymes in cheese curd was confirmed, and a potential role in production of bitter peptides identified. Cheeses made from milks containing high levels of PMNs had accelerated αs1-casein breakdown relative to cheeses made from low PMN milk of the same total SCC, consistent with the demonstrated action of PMN proteinases. The two types of cheese were determined significantly different by blind triangle testing.

Studies on factors relating to the development of defects in commercial cheese

Defects in commercial cheese result in a downgrading of the final cheese and a consequential economic loss to the cheese producer. Developments of defects in cheese are often not fully understood and therefore not controllable by the producer. This research investigated the underlying factors in the development of split and secondary fermentation defect and of pinking defects in commercial Irish cheeses. Split defect in Swiss-type cheese is a common defect associated with eye formation and manifests as slits and cracks visible in the cut cheese loaf (Reinbold, 1972; Daly et al., 2010). No consensus exists as to the definitive causes of the defect and possible factors which may contribute to the defect were reviewed. Models were derived to describe the relationship between moisture, pH, and salt levels and the distance from sample location to the closest external block surface during cheese ripening. Significant gradients within the cheese blocks were observed for all measured parameters in cheeses at 7 day post/after manufacture. No significant pH gradient was found within the blocks on exit from hot-room ripening and at three months post exit from the hot-room. Moisture content reached equilibrium within the blocks between exit from hot-room and 3 months after exit from hot-room while salt and salt-to-moisture levels had not reached equilibrium within the cheese blocks even at three months after exit from hot-room ripening. A characterisation of Swiss-type cheeses produced from a seasonal milk supply was undertaken. Cheeses were sampled on two days per month of the production year, at three different times during the manufacturing day, at internal and external regions of the cheese block and at four ripening time points (7 days post manufacture, post hot-room, 14 days post hot-room and 3 months in a cold room after exit from hot-room). Compositional, biochemical and microbial indices were determined, and the results were analysed as a splitplot with a factorial arrangement of treatments (season, time of day, area) on the main plot and ripening time on the sub-plot. Season (and interactions) had a significant effect on pH and salt-in-moisture levels (SM), mean viable counts of L. helveticus, propionic acid and non-starter lactic acid bacteria, levels of primary and secondary proteolysis and cheese firmness. Levels of proteolysis increased significantly during hot-room ripening but also during cold room storage, signifying continued development of cheese ripening during cold storage (> 8°C). Rheological parameters (e.g. springiness and cohesiveness) were significantly affected by interactions between ripening and location within cheese blocks. Time of day of manufacture significantly affected mean cheese calcium levels at 7 days post manufacture and mean levels of arginine and mean viable counts of NSLAB. Cheeses produced during the middle of the production day had the best grading scores and were more consistent compared to cheeses produced early or late during day of manufacture. Cheeses with low levels of S/M and low values of resilience were associated with poor grades at 7 days post manufacture. Chesses which had high elastic index values and low values of springiness in the external areas after exit from hot-room ripening also obtained good commercial grades. Development of a pink colour defect is an intermittent defect in ripened cheese which may or may not contain an added colourant, e.g., annatto. Factors associated with the defect were reviewed. Attempts at extraction and identification of the pink discolouration were unsuccessful. The pink colour partitioned with the water insoluble protein fraction. No significant difference was observed between ripened control and defect cheese for oxygen levels and redox potential or for the results of elemental analysis. A possible relationship between starter activity and defect development was established in cheeses with added coulourant, as lower levels of residual galactose and lactose were observed in defective cheese compared to control cheese free of the defect. Swiss-type cheese without added colourant had significantly higher levels of arginine and significantly lower lactate levels. Flow cell cytometry indicated that levels of bacterial cell viability and metabolic state differed between control and defect cheeses (without added colourant). Pyrosequencing analysis of cheese samples with and without the defect detected the previously unreported bacteria in cheese, Deinococcus thermus (a potential carotenoid producer). Defective Swiss-type cheeses had elevated levels of Deinococcus thermus compared to control cheeses, however the direct cause of pink was not linked to this bacterium alone. Overall, research was undertaken on underlying factors associated with the development of specific defects in commercial cheese, but also characterised the dynamic changes in key microbial and physicochemical parameters during cheese ripening and storage. This will enable the development of processing technologies to enable seasonal manipulation of manufacture protocols to minimise compositional and biochemical variability and to reduce and inhibit the occurrence of specific quality defects.