A novel artificial habitat collection device for studying resettlement patterns in anguillid glass eels

The number of glass eels Anguilla australis and A. reinhardtii caught in artificial habitat collectors, made from a PVC base and polyethylene split rope fibres, was related to the number of rope fibre tufts attached to each collector rather than collector area directly. Ageing of collectors in situ to promote algal growth enhanced the catch of glass eels. Glass eels entered the collectors at night primarily during the flood tide, and did not move into the collectors during daylight hours. Glass eel abundance increased with increasing distance from the freshwater drain located in the causeway. The artificial habitat collectors are effective for assessing relative numbers of resettling glass eels and may be useful for studying recruitment and settlement patterns of other anguillid eel species, as well as identifying areas and habitats within a catchment that provide important shelter for glass eels. Sampling glass eels can be carried out with maximum effect and minimum effort using compact, aged artificial habitat collectors on the night time flood tide when low tide coincides with dusk.     

用于寡核苷酸芯片制备载体的醛基载玻片的制备方法优化及性质研究

优化了醛基载玻片的制备方法 ,探讨了醛基修饰载玻片固定寡核苷酸探针的性质。研究发现氨基硅烷试剂的浓度是影响载玻片荧光背景的主要因素 ;2 %氨基化试剂处理 16min、戊二醛处理 30min可以得到荧光背景较低、固定效果较好的醛基载玻片。寡核苷酸固定过程中 ,末端氨基修饰没有明显的特异性 ,但是可以提高被固定探针的杂交容量。在较低的浓度 (小于 10 μmol L)时 ,探针的浓度与杂交信号趋近线性关系 ,浓度为 2 0 μmol L时杂交信号达到饱和     

Penicillium rubens germination on desiccated and nutrient-depleted conditions depends on the water activity during sporogenesis

Fungal growth often appears in a surrounding where water and nutrients are scarce. The impact of this environment during sporogenesis on subsequent growth is often neglected.This study investigates the effect of water availability during sporogenesis on subsequent early growth. Therefore, a carbon-depleted substrate was constructed. Humidity is then the only parameter of interest. The water conditions during sporogenesis, and during subsequent growth, were varied. This is a stressing environment: no carbon source is present, and water provided solely via the vapour.The lag time, $t_l$, and initial growth rate, ${\mu }_{fp}$, of the germ tubes were monitored.The effect of $a_w$ history on germination and initial growth depends on the $RH$ of the environment. Only at low $RH$ do spores produced at low $a_w$ have a smaller $t_l$ and higher ${\mu }_{fp}$ compared to those grown at high $a_w$. This result was remarkably pronounced when the substrate was also made hydrophobic: growth only occurred when spores were developed at low $a_w$ and placed in high $RH$.Spores grown on lowered $a_w$ attract more water. It is hypothesized that this attraction affects subsequent growth behaviour, and is the reason why growth on hydrophobic glass only prevails in the condition of high $RH$ and lowered $a_w$ history.We demonstrate the influence of cultivation conditions on germination, which becomes more pronounced in a more desiccated environment.     

Emission analysis of Tb3+‐and Sm3+‐ion‐doped (Li2O/Na2O/K2O) and (Li2O + Na2O/Li2O + K2O/K2O + Na2O)‐modified borosilicate glasses

Four series of borosilicate glasses modified by alkali oxides and doped with Tb³⁺ and Sm³⁺ ions were prepared using the conventional melt quenching technique, with the chemical composition 74.5B₂O₃ + 10SiO₂ + 5MgO + R + 0.5(Tb₂O₃/Sm₂O₃) [where R = 10(Li₂O /Na₂O/K₂O) for series A and C, and R = 5(Li₂O + Na₂O/Li₂O + K₂O/K₂O + Na₂O) for series B and D]. The X‐ray diffraction (XRD) patterns of all the prepared glasses indicate their amorphous nature. The spectroscopic properties of the prepared glasses were studied by optical absorption analysis, photoluminescence excitation (PLE) and photoluminescence (PL) analysis. A green emission corresponding to the ⁵D₄ → ⁷F₅ (543 nm) transition of the Tb³⁺ ions was registered under excitation at 379 nm for series A and B glasses. The emission spectra of the Sm³⁺ ions with the series C and D glasses showed strong reddish‐orange emission at 600 nm (⁴G_5/2 →⁶H_7/2) with an excitation wavelength λ_exci = 404 nm (⁶H_5/2→⁴F_7/2). Furthermore, the change in the luminescence intensity with the addition of an alkali oxide and combinations of these alkali oxides to borosilicate glasses doped with Tb³⁺ and Sm³⁺ ions was studied to optimize the potential alkali‐oxide‐modified borosilicate glass.     

Changes in the fatty acid profile of the Australian shortfin eel in relation to development

In glass eels (54 mm TL; 0.018 g) of the Australian shortfin eel Anguilla australis the fatty acid composition was typical of marine species, with a n-3 to n-6 ratio of 5.3, a low level of mono saturated fatty acids (monoenes) and a high level of polyunsaturated fatty acids (PUFA). In elvers (pigmented: 56 mm TL; 0.028 g), the n-3 to n-6 ratio was 2.6. In elvers monoenes, as per cent of all identifiable fatty acids, increased to 30.9% from that of 19.8% in glass eels. The fatty acid composition of juvenile eels, reared from the original stock of glass eels and elvers, in outdoor, fertilized ponds, with (115 mmTL; 2.2 g) and without feeding (110 mmTL; 1.9 g), had a fatty acid composition typical of freshwater species, with a n-3 to n-6 ratio 1.9 and 1.3, and 37.7 and 46.5% of monoenes in unfed and fed groups respectively. A principal component analysis summarized efficiently the progressive changes in fatty acid composition from the glass eel to juvenile eel stage. The observed changes in the fatty acid of the different developmental stages in Australian shortfin eel are discussed in relation to physiological changes associated with the diadromous habit.     

Subtractive hybridization of cDNA from small amounts of plant tissue

A subtractive hybridization method is described that allows the generation of a subtractive gene library from small amounts of plant or other eukaryotic tissues. The method uses paramagnetic oligo-dT beads to capture poly-adenylated mRNA and to synthesize the complementary cDNA on a solid support. The use of magnetic beads facilitates the change of reaction buffers and the removal of primers and minimizes yield losses. Subtracted material obtained from this method can either be cloned directly or used to screen a specific library.     

Storage behavior of Typha latifolia pollen at low water contents: Interpretation on the basis of water activity and glass concepts

Germplasm must be stored under optimal conditions to maximize longevity and efficiently maintain genetic resources. In order to identify optimal storage conditions, we investigated the effects of temperature (−5 to 45°C) and water content (<0.17 g H₂O g⁻¹ dry weight) on longevity of Typha latifolia L. pollen. Longevity was highest at water contents corresponding to storage relative humidity (RH) of 11‐15% which corresponded to the shoulder of water sorption isotherms. Also coinciding with this shoulder were abrupt changes in heat capacity of water present in the pollen. Consistent with changes in isotherms with temperature and the concept of critical RH for storage, optimum water contents increased with decreasing temperature. An attempt was made to explain the aging behavior according to the glass concept. The water content‐temperature combinations of optimal storage were found to be below the glass transition curve, indicating that optimum storage conditions are achieved when intracellular glasses are present. We also found a change in activation energy of aging in Arrhenius plots around T_g, demonstrating a change in aging kinetics when the glassy state is lost. We concluL that T_g curves cannot be used solely to predict precise conditions of optimum storage, but might be useful for predictions of storage longevity above optimum water contents. The data imply that too much drying reduces longevity and should be avoided, particularly when cryogenic storage is considered.     

Location,size and age at onset of metamorphosis in the Japanese eel Anguilla japonica

This study clarifies the location, size and age at the onset of metamorphosis in Japanese eels Anguilla japonica through oceanic surveys, rearing experiments and analyses of the morphology and otoliths of leptocephali and glass eels. Twenty‐eight metamorphosing leptocephali were collected in the mesoscale eddy region to the east of Taiwan during research expeditions in 2004. Rearing experiments showed that the total length (L_T) of leptocephali decreased by an average of 12·5% during metamorphosis and 13·9% during the 2–12 h after death. Thus, the mean back‐calculated L_T at the onset of metamorphosis for 630 glass eels from Taiwan and Japan was estimated at 67·8 ± 2·7 mm (mean ± S.D.). The estimated mean ante‐mortem size of the fully grown pre‐metamorphic leptocephali collected in 2004 was 64·6 ± 3·4 mm, which was consistent with the L_T estimate for glass eels. Otolith analysis showed that the mean age at the onset of metamorphosis was 137 ± 15 days and indicated that Japanese eels may have a recruitment route through the mesoscale eddies to the east of Taiwan in addition to the direct transfer route from the North Equatorial Current to the Kuroshio Current.     

Clones or clans: the genetic structure of a deep‐sea sponge,Aphrocallistes vastus,in unique sponge reefs of British Columbia,Canada

Understanding patterns of reproduction, dispersal and recruitment in deep‐sea communities is increasingly important with the need to manage resource extraction and conserve species diversity. Glass sponges are usually found in deep water (>1000 m) worldwide but form kilometre‐long reefs on the continental shelf of British Columbia and Alaska that are under threat from trawling and resource exploration. Due to their deep‐water habitat, larvae have not yet been found and the level of genetic connectivity between reefs and nonreef communities is unknown. The genetic structure of Aphrocallistes vastus, the primary reef‐building species in the Strait of Georgia (SoG) British Columbia, was studied using single nucleotide polymorphisms (SNPs). Pairwise comparisons of multilocus genotypes were used to assess whether sexual reproduction is common. Structure was examined 1) between individuals in reefs, 2) between reefs and 3) between sites in and outside the SoG. Sixty‐seven SNPs were genotyped in 91 samples from areas in and around the SoG, including four sponge reefs and nearby nonreef sites. The results show that sponge reefs are formed through sexual reproduction. Within a reef and across the SoG basin, the genetic distance between individuals does not vary with geographic distance (r = ?0.005 to 0.014), but populations within the SoG basin are genetically distinct from populations in Barkley Sound, on the west coast of Vancouver Island. Population structure was seen across all sample sites (global F_ST = 0.248), especially between SoG and non‐SoG locations (average pairwise F_ST = 0.251). Our results suggest that genetic mixing occurs across sponge reefs via larvae that disperse widely.