New species of the eel genera Dysomma and Dysommina from Vietnam,South China Sea (Anguilliformes: Synaphobranchidae)

Two new cutthroat eel species are described from Vietnam. Dysomma intermedium sp. nov. has a relatively long trunk, being about half of head length and anal-fin origin more than twice pectoral-fin length behind the pectoral-fin tip; pectoral fin well developed; dorsal-fin origin over or slightly in front of base of pectoral fin; two intermaxillary teeth; four or five compound teeth on ethmovomer; single row of seven or eight teeth on lower jaw; total lateral-line pores 70–76; and 21 pre-anal and 118–124 total vertebrae. Dysommina brevis sp. nov. differs from congeners by having a trunk shorter than head length, its length 11.1%–11.8% TL; a short pre-anal length 24.6%–25.6% TL, eye diameter 11.8%–12.3% head length; three large and one or two small teeth on ethmovomer; and fewer teeth on the upper and lower jaws. In addition, a specimen representing the first record of Dysommina orientalis in Vietnamese water is documented.     

Fungal beta-N-acetylhexosaminidases with high beta-N-acetylgalactosaminidase activity and their use for synthesis of beta-GalNAc-containing oligosaccharides

About 60 fungal strains were tested for production of extracellular beta-N-acetylhexosaminidases. A unique beta-N-acetylhexosaminidase with the beta-GalNAc-ase/beta-GlcNAc-ase ratio of 2.3-2.8 was found in the culture filtrates of some strains of Penicillium oxalicum. Addition of 20% (w/v) MgSO(4) increased the beta-GalNAc-ase/beta-GlcNAc-ase ratio to the value of 3.35. Cultivation conditions influence this ratio as well. beta-N-Acetylhexosaminidases from P. oxalicum CCF 2430 and Aspergillus oryzae CCF 1066 considerably differing in the GalNAc-ase activity were used for the synthesis of the following structures beta-D-GalpNAc-(1-->4)-D-GlcpNAc, beta-D-GalpNAc-(1-->6)-D-GlcpNAc, beta-D-GalpNAc-(1-->6)-D-GalpNAc, beta-D-GalpNAc-(1-->4)-alpha-D-GlcpNAcOAll and beta-D-GalpNAc-(1-->6)-beta-D-Galp-(1-->4)-alpha-D-GlcpNAcOAll to demonstrate the application of these new enzymes.     

Untersuchungen zur modifikation der cellobiose und synthese von methyl-2,6-didesoxy-4-O-(6-desoxy-β-D-glucopyranosyl)-α-D-arabino-hexopyranosid (methyl-4-O-β-D-chinovosyl-α-D-olivosid)

Starting with cellobiosides, several different procedures were employed to prepare 6,6′-dichloro-6,6′-dideoxy, 6,6′-dibromo-6,6′-dideoxy, and 6,6′-dideoxy-6,6′-diiodo derivatives. Reduction with lithium aluminum hydride or nickel boride afforded peracetyl derivatives of methyl, phenyl, and benzyl 6-deoxy-4-O-(6-deoxy-β-D-glucopyranosyl)-β-D-glucopyranoside. Following acetolysis or hydrogenolysis, the glycosyl halide and the corresponding-glycal 40 were prepared. Iodomethoxylation of 40 and subsequent reduction gave the title compound. Alternatively, the halomethoxylation products of cellobial hexaacetate gave, by various procedures, the 2,6,6′-trideoxy-2,6,6′-trihalo derivatives, which, in turn, could be reduced to the title compound. The structures of the derivatives prepared were unequivocally assigned by n.m.r. spectroscopy. The various reaction sequences were compared with respect to the number of steps and the yields obtained.     

Potential use of ageing cultures ofIsochrysis aff.galbana (Isochrysis Tahitian,T. Iso) as starter cultures for live algal food production in tropical aquaculture

When grown in batch culture for a prolonged period (up to 11 months), the cells ofIsochrysis aff.galbana (Isochrysis Tahitian strain T. Iso) lost their capacity to divide and became enlarged, with a reduction in the content of photosynthetic pigment and photosynthetic capacity. Upon returning to fresh medium, the cells of a 11-month-old culture regained their capacity to divide within 3 days under light conditions. The resulting cells possessed similar size, photosynthetic pigment and photosynthetic capacity as those of logarithmic growth phase. The results suggest that the aged cultures ofIsochrysis can be used as starter cultures for the production of live food for aquaculture animals.     

Transport pathways shape the biogeography of alien freshwater fishes in Australia

Aim

Changing preferences regarding which species humans have transported to new regions can have major consequences for the potential distribution of alien taxa, but the mechanisms shaping these patterns are poorly understood. We assessed the extent to which changes in human preferences for transporting and introducing alien freshwater fishes have altered their biogeography.

Location

Australia.

Methods

We compiled an up‐to‐date database of alien freshwater fishes established in drainages in Australia before and after the number of established alien fish species doubled (pre‐1970 and post‐1970, respectively). Using metacommunity models, we analysed the influence of species traits and drainage features on the distribution of alien fishes that established pre‐ and post‐1970.

Results

Alien fishes in Australia were introduced via four main transport pathways: acclimatization, aquaculture, biocontrol and ornamental trade. The relative importance of each pathway changed substantially between the two periods, accompanied by changes in the distribution of alien fishes and the variables predicting their distribution. Pre‐1970, most species (64%) were introduced by acclimatization societies for purposes such as angling and biocontrol, and these fish have established in inland drainages more heavily impacted by human activities. In contrast, most of the post‐1970 introductions (69%) were ornamental fishes, with most species established in small, north‐eastern, tropical and subtropical coastal drainages.

Main conclusions

Substantial changes in introduction preferences and transport pathways over time have altered both the patterns and underlying processes shaping the biogeography of alien fishes in Australia. Our findings highlight the need for caution when using historical data to infer potential future distributions of alien species. The continuing spread of alien species means traditional biogeographical units may no longer be identifiable in the foreseeable future.

     

A multiplexed set of microsatellite markers for discriminating <Emphasis Type="Italic">Acacia mangium</Emphasis>, <Emphasis Type="Italic">A. auriculiformis</Emphasis>, and their hybrid

In order to assist breeding and gene pool conservation in tropical Acacias, we aimed to develop a set of multipurpose SSR markers for use in both Acacia mangium and A. auriculiformis. A total of 51 SSR markers (developed in A. mangium and natural A. mangium x A. auriculiformis hybrid) were tested. A final set of 16 well-performing SSR markers were identified, six of which were species diagnostic. The markers were optimized for assay in four multiplex mixes and used to genotype range-wide samples of A. mangium, A. auriculiformis, and putative F₁ hybrids. Simulation analysis was used to investigate the power of the markers for identifying the pure species and their F₁, F₂, and backcross hybrids. The six species diagnostic markers were particularly powerful for detecting F₁ hybrids from pure species but could also discriminate the pure species from F₂ and backcross progenies in most cases (97 %). STRUCTURE analysis using all 16 markers was likewise able to distinguish these cross types and pure species sets. Both sets of markers had difficulties in distinguishing F₂ and backcross progenies. However, identifying F₁ from pure species is the current primary concern in countries where these species are planted. The SSR marker set also has direct application in DNA profiling (probability of identity?=?4.1?×?10^?13), breeding system analysis, and population genetics.     

Recovery from a fish kill in a semi‐arid Australian river: Can stocking augment natural recruitment processes?

Localized catastrophic events can dramatically affect fish populations. Management interventions, such as stocking, are often undertaken to re‐establish populations that have experienced such events. Evaluations of the effectiveness of these interventions are required to inform future management actions. Multiple hypoxic blackwater events in 2010–2011 substantially reduced fish communities in the Edward‐Wakool river system in the southern Murray‐Darling Basin, New South Wales, Australia. These events led to extensive fish kills across large sections of the entire system following a period of prolonged drought. To expedite recovery efforts, 119 661 golden perch Macquaria ambigua and 59 088 Murray cod Maccullochella peelii fingerlings were stocked at five locations over 3 years. All fish stocked were chemically marked with calcein to enable retrospective evaluation of wild or hatchery origin. Targeted collections were undertaken 3 years post‐stocking to investigate the relative contribution of stocking efforts and recovery via natural recruitment in the system. Of the golden perch retained for annual ageing (n = 93) only nine were of an age that could have coincided with stocking activities. Of those, six were stocked. The dominant year‐class of golden perch were spawned in 2009; before the stocking programme began and prior to blackwater events. All Murray cod retained (n = 136) were of an age that coincided with stocking activities, although only eight were stocked. Among the Murray cod captured, the dominant year‐class was spawned in 2011, after the blackwater events occurred. The results from this study provide first evidence that natural spawning and recruitment, and possibly immigration, were the main drivers of golden perch and Murray cod recovery following catastrophic fish kills. Interpreted in the context of other recent examples, the collective results indicate limited benefit of stocking to existing connected populations already naturally recruiting in riverine systems.