Breaking the trade-off: rainforest bats maximize bandwidth and repetition rate of echolocation calls as they approach prey

Both mammals and birds experience a performance trade-off between producing vocalizations with high bandwidths and at high repetition rate. Echolocating bats drastically increase repetition rate from 2–20 calls s⁻¹ up to about 170 calls s⁻¹ prior to intercepting airborne prey in order to accurately track prey movement. In turn, bandwidth drops to about 10–30 kHz for the calls of this ‘final buzz’. We have now discovered that Southeast Asian rainforest bats (in the vespertilionid subfamilies Kerivoulinae and Murininae) are able to maintain high call bandwidths at very high repetition rates throughout approach to prey. Five species of Kerivoula and Phoniscus produced call bandwidths of between 78 and 170 kHz at repetition rates of 140–200 calls s⁻¹ and two of Murina at 80 calls s⁻¹. The ‘typical’ and distinct drop in call frequency was present in none of the seven species. This stands in striking contrast to our present view of echolocation during approach to prey in insectivorous bats, which was established largely based on European and American members of the same bat family, the Vespertilionidae. Buzz calls of Kerivoula pellucida had mean bandwidths of 170 kHz and attained maximum starting frequencies of 250 kHz which makes them the most broadband and most highly pitched tonal animal vocalization known to date. We suggest that the extreme vocal performance of the Kerivoulinae and Murininae evolved as an adaptation to echolocating and tracking arthropods in the dense rainforest understorey.     

Wavelet neural networks applied to pulping of oil palm fronds

In the organosolv pulping of the oil palm fronds, the influence of the operational variables of the pulping reactor (viz. cooking temperature and time, ethanol and NaOH concentration) on the properties of the resulting pulp (yield and kappa number) and paper sheets (tensile index and tear index) was investigated using a wavelet neural network model. The experimental results with error less than 0.0965 (in terms of MSE) were produced, and were then compared with those obtained from the response surface methodology. Performance assessment indicated that the neural network model possessed superior predictive ability than the polynomial model, since a very close agreement between the experimental and the predicted values was obtained.     

Lentivirus vector driven by polybiquitin C promoter without woodchuck posttranscriptional regulatory element and central polypurine tract generates low level and short-lived reporter gene expression

Hereditary myopathy with lactic acidosis (HML) (OMIM #255125) presents in childhood with exercise intolerance and muscle pain on trivial exercise, lactic acidosis, dyspnoea, palpitations, and rhabdomyolysis which can be fatal. The disease is recessively inherited and caused by a deep intronic, single base transition in the iron-sulfur cluster scaffold, ISCU gene that causes retention of a pseudoexon and introduction of a premature termination codon. IscU protein deficiency causes secondary defects in several iron-sulfur dependant proteins, including enzymes involved in aerobic energy metabolism. We have shown in a previous study that the splice abnormality affects skeletal muscle more than other tissues, leading to the purely muscular phenotype.Antisense oligonucleotides (AOs) have been able to redirect mRNA splicing in a number of disease models, and show promise in clinical studies. We designed 2′O-methyl phosphorothioate AOs targeting either splice site of the detrimental HML pseudoexon. The acceptor site AO effectively redirected splicing towards the normal state in cultured muscle fibroblasts, whilst the donor site AO promoted pseudoexon inclusion in both patient and control cells. Our results show that AO therapy seems feasible in HML, but care must be taken to avoid adverse splicing effects.     

Production of an oligosaccharide-specific cellobiohydrolase from the thermophilic fungus <Emphasis Type="Italic">Thielavia terrestris</Emphasis>

Objectives

To express and determine the hydrolytic activity of a cellobiohydrolase (TTCBH6B) from the thermophilic fungus Thielavia terrestris in Pichia pastoris.

Results

Ttcbh6B encodes a protein of 507 amino acid residues with a predicted molecular mass of 54 kDa. TTCBH6B contains a familial 6-glycosyl hydrolase catalytic domain and a type I carbohydrate-binding module. TTCBH6B was expressed and purified to homogeneity but the purified enzyme was inactive against Avicel. It could, however, digest Celluclast-treated Avicel producing cellobiose (0.27 μmol min^?1 mg^?1). To determine the substrate preferences of TTCBH6B, oligosaccharides of varying numbers of subunits were generated by acid hydrolysis of Avicel and fluorescently tagged. Peaks corresponding to oligosaccharides containing three to six glucose units were reduced to cellobiose after addition of TTCBH6B.

Conclusion

TTCBH6B is active against shorter oligosaccharides rather than polysaccharides.

     

Evolution of specialized spermatheca morphology in ant queens: Insight from comparative developmental biology between ants and polistine wasps

In many ant species, the queens can keep spermatozoa alive in their spermatheca for several years, which goes along with unique morphological characteristics of the queen's spermatheca. The relative spermatheca size in ant queens is prominently larger than that in social wasps. Furthermore, the epithelium lining the spermatheca reservoir of ants consists of columnar cells in the hilar region and squamous cells in the distal region, whereas it is formed by columnar cells only in social wasps. To study the evolution of the unique spermatheca morphology in ant queens, we compared the various processes during spermatheca development between two ponerine ant species of the genus Pachycondyla (= Brachyponera) and three polistine wasp species of the genus Polistes. From histological observations, we can define four developmental events in the ant queens: (1) invagination of the spermatheca primordium, (2) the reservoir wall thickness becomes unequal, (3) the reservoir diameter doubles as the lining epithelial cells become flattened except for the hilar region, and (4) the increase in thickness of the reservoir epithelium is limited to the hilar region which doubles in thickness. In polistine wasps, the second and the third developmental events are absent and the entire epithelium of the spermatheca wall becomes thick in the final step. We therefore conclude that for ant queens the second and third steps are crucial for the enlargement of the spermatheca size, and that the second to the fourth steps are crucial for the specialization of the reservoir wall structure.     

Exploiting an oil palm EST database for the development of gene-derived SSR markers and their exploitation for assessment of genetic diversity

A total of 5,521 expressed sequence tags (ESTs) from oil palm were used to search for type and frequency of simple sequence repeat (SSR) markers. Dimeric repeat motifs appeared to be the most abundant, followed by tri-nucleotide repeats. Redundancy was eliminated in the original EST set, resulting in 145 SSRs in 136 unique ESTs (114 singletons and 22 clusters). Primers were designed for 94 (69.1%) of the unique ESTs (consisting of 14 consensus and 80 singletons). Primers for 10 EST-SSRs were developed and used to evaluate the genetic diversity of 76 accessions of oil palm originating from seven countries in Africa, and the standard Deli dura population. The average number of observed and effective alleles was 2.56 and 1.84, respectively. The EST-SSR markers were found to be polymorphic with a mean polymorphic information content value of 0.53. Genetic differentiation (F _ST) among the populations studied was 0.2492 indicating high level of genetic divergence. Moreover, the UPGMA (unweighted pair-group method with arithmetic mean) analysis revealed a strong association between genetic distance and geographic location of the populations studied. The germplasm materials exhibited higher diversity than Deli dura, indicating their potential usefulness in oil palm improvement programmes. The study also revealed that the populations from Nigeria, Congo and Cameroon showed the highest diversity among the germplasm evaluated in this study. The EST-SSRs further demonstrated their worth as a new source of polymorphic markers for phylogenetic analysis, since a high percentage of the markers showed transferability across species and palm taxa.     

Eyespan reflects reproductive quality in wild stalk-eyed flies

Handicap models of sexual selection propose that females use male sexual ornaments as a cue in mate choice because they reflect commodities that increase female fitness, either directly or indirectly. In contrast to studies on vertebrates, most investigations of ornaments in insects and other invertebrate taxa have been conducted under laboratory conditions. There is a pressing need to address questions relating to sexual signalling of quality in natural populations, as the arbitrary and uniform environments found in the laboratory fail to reflect the world under which animals have evolved. We investigated associations between male ornaments (exaggerated eyespan), attractiveness, and reproductive quality in a wild population of the sexually ornamented stalk-eyed fly, Teleopsis dalmanni. We also explored the relationship between eyespan and reproductive quality in females to evaluate the potential for sexually antagonistic selection on eyespan. We show that eyespan is a generic correlate of reproductive quality, acting as a reliable mirror of variation in reproductive fitness in both sexes. Our findings suggest that male ornaments signal commodities that are of interest to females in the natural environment in which they, and mate preferences for them, have evolved. In addition, the covariance between female eyespan and reproductive output suggests that the former may be a reliable cue of quality in its own right. Our data provide important insights into the evolutionary forces that shape the evolution of exaggerated eyespan in wild populations of this species.     

Comparison of spermatheca morphology between reproductive and non-reproductive females in social wasps

Social wasps show an obvious evolution of the differentiation in behavior and external size between reproductive and non-reproductive females, with no clear differences in the Stenogastrinae, via overlap in the Polistinae, to clear differences in the Vespinae. In this study, we examined the morphological appearance of the spermatheca in representative species of these three subfamilies. The general anatomical organization of the spermatheca comprises a reservoir, a duct and two spermathecal glands, and is in line with its common structure in other social Hymenoptera. All examined wasp species have a spermathecal reservoir with uniform wall thickness, which is similar to the situation in the bees, but differentiates them from the ants. Within the wasps, the shape of the reservoir, the shape of the spermathecal glands and their attachment site to the spermatheca differs among the Stenogastrinae, Polistinae and Vespinae. The reservoir wall is thick in the Polistinae and Vespinae, while in the Stenogastrinae, it varies from thin in Parischnogaster to thick in Eustenogaster, with an intermediate situation in Liostenogaster. In all examined species, we found no differences in the spermathecal development between reproductive and non-reproductive wasps.