Yuh-Wen Chiu

Cloning, expression, and characterization of cadmium-induced metallothionein-2 from the earthworms Metaphire posthuma and Polypheretima elongata.

In this study we report the sequences of MT-2 cDNA from two species of Megascoleidae earthworms, Metaphire posthuma and Polypheretima elongata, by mRNA differential display after exposure of the organisms to cadmium. Complementary (c)DNA was verified as the MT-2 gene by the characteristics of its predicted translation product, namely a high cysteine content, conserved CXC motifs, and a molecular weight of around 8 kDa. Amino acid sequence alignment revealed a conserved TKCCG in the cloned MT-2 of both megascolecid earthworms instead of the corresponding conserved TQCCG found in lumbricid earthworms. The cDNAs corresponding to the two megascolecid MT-2 genes were expressed, and the MT-2 proteins were purified for biochemical characterization. The binding of Cu2+ exhibited monophasic kinetics and those of Zn2+ and Cd2+ biphasic kinetics. The proteins bound more tightly to Cd2+ than to Zn2+ and more tightly still to Cu2+. Zn-MT and apo-MT were the most effective at scavenging free radicals, followed by Cd-MT. In conclusion, MT-2s from M. posthuma and P. elongata showed unique sequence features compared to those of lumbricid earthworms. These earthworms could be used to evaluate heavy-metal pollution in soil due to the inducible MT-2 by cadmium exposure.

Acoustic and temporal partitioning of cicada assemblages in city and mountain environments.

Comparing adaptations to noisy city environments with those to natural mountain environments on the community level can provide significant insights that allow an understanding of the impact of anthropogenic noise on invertebrates that employ loud calling songs for mate attraction, especially when each species has its distinct song, as in the case of cicadas. In this study, we investigated the partitioning strategy of cicada assemblages in city and mountain environments by comparing the acoustic features and calling activity patterns of each species, recorded using automated digital recording systems. Our comparison of activity patterns of seasonal and diel calling revealed that there was no significant temporal partitioning of cicada assemblages in either environment. In addition, there was no correlation between the acoustic distance based on spectral features and temporal segregation. Heterospecific spectral overlap was low in both city and mountain environments, although city and mountain cicada assemblages were subject to significantly different levels of anthropogenic or interspecific noise. Furthermore, for the common species found in both environments, the calling activity patterns at both seasonal and diel time scales were significantly consistent across sites and across environments. We suggest that the temporal calling activity is constrained by endogenous factors for each species and is less flexible in response to external factors, such as anthropogenic noise. As a result, cicada assemblages in city environments with low species diversity do not demonstrate a more significant temporal partitioning than those in mountain environments with high species diversity.

LOCAL DISTRIBUTION AND TEMPERATURE PREFERENCES OF PREDATORY WHELKS (THAIS SPP.) IN TAIWAN: IMPLICATIONS FOR OYSTER CULTURE

Abstract Among the Thais species, the broad consensus has long been that Thais clavigera (Kuster) is the most noxious predator of cultured oysters in Taiwan. Recently, two new Thais species (i.e., T. rufotincta Tan & Sigurdsson 1996 and T. keluo Tan & Liu 2001) have been identified and named in Taiwanese waters yet their impact on oyster culture is unknown. In this study, the overall impact of the three species on the oyster industry was estimated on the basis of their distribution in the field, their feeding rate and their temperature preference based on laboratory tests. The proportion of T. clavigera varied monthly from 24% to 100%, whereas the percentage of T. keluo was negatively correlated with low tide levels (P < 0.01). Thais clavigera occurred widely in the intertidal zone and T. keluo and T. rufotincta near the subtidal, this distribution pattern was consistent with their specific-preferred temperatures in the upper-limits. As shown in the laboratory, T. clavigera, T. rufotincta and T. keluo preferred 36°C, 32C° and 30°C water, respectively. In the field, the respective average feeding rate of T. clavigera, T. rufotincta and T. keluo was significantly different at 0.054, 0.010 and 0.038 oysters snail−1 day−1 (P < 0.05). Based on the abundance of the three Thais species at oyster cultural sites (Liu 2002) and their feeding rates, when oyster predation was made up of T. clavigera, T. rufotincta and T. keluo, predation was respectively 87%, 11% and 2%. The most destructive Thais species in the oyster industry remains T. clavigera, and it accounts for 87% to 100% of all intertidal losses in Taiwan. To the other one-third subtidal culture industry, owing to the use of off-bottom raft or longline method, the distribution of snails extended to subtidal may be limited and the reported major predator is the flatworm of Stylochus orientalis.

Interspecific comparison of traffic noise effects on dove coo transmission in urban environments

Most previous studies concerning avian adaptation to anthropogenic noise have focused on songbirds, but few have focused on non-songbirds commonly found in urban environments such as doves. We conducted field playback-recording experiments on the perch-coos of five dove species, including four native Taiwan species (the spotted dove, Spilopelia chinensis, the oriental turtle-dove, Streptopelia orientalis, the red collared-dove, Streptopelia tranquebarica, and the emerald dove, Chalcophaps indica) and one species not native to Taiwan (the zebra dove, Geopelia striata) to evaluate the detection and recognition of dove coos in habitats with differing levels of traffic noise. Our results suggest that traffic noise has selected dominant urban species such as the spotted dove to temporally and spatially adjust cooing to reduce the masking effects of traffic noise and rare urban species such as the emerald dove to avoid areas of high traffic noise. Additionally, although the zebra dove had the highest coo frequency among the study species, its coos showed the highest detection value but not the highest recognition value. We conclude that traffic noise is an important factor in shaping the distribution of rare and dominant dove species in urban environments through its significant effects on coo transmission.