Expression of a mouse metallothionein-Escherichia coli β-galactosidase fusion gene (MT-βgal) in early mouse embryos

We have microinjected DNA containing the inducible mouse metallothionein-I (MT-I) promoter, coupled to the structural gene for Escherichia coli β-galactosidase (lacZ), into the pronuclei of one-cell mouse embryos. A qualitative histochemical assay, with 5-bromo-4-chloro-3-indolylβ- -galactopyranoside (X-Gal) as a substrate, was used to detect expression of lacZ at several preimplantation stages. We observed staining indicative of exogenous β-galactosidase activity in 5–17% of DNA-injected embryos assayed at preimplantation stages after 16–24 h treatment with ZnSO₄. Thus, lacZ can be used as an indicator gene for promoter function during early mouse embryogenesis, and the incorporation of the MT-I promoter into fusion genes can be a useful means of controlling the expression of exogenous genes in preimplantation mouse embryos.     

Assessment of populations ofGracilaria chilensis (Graeilariales,Rhodophyta) utilizing RAPDs

Phenotypic variability and mixing of material due to massive cultivation for commercial purposes has contributed to the taxonomic confusion ofGracilaria in Chile. At least four species with cylindrical thalli and similar morphology have been recorded. However, since establishment ofG. chilensis, most of the collected thalli have been attributed to this species despite the lack of diagnostic features. In an attempt to resolve whetherGracilaria from 3 localities where it grows in natural and artificial populations belongs to the same species, gametophytic samples were compared by applying RAPD-PCR to their total DNA. This was analysed using 25 different 10-mer primers from which 21 revealed polymorphism within and between populations. Similarity matrices and cluster analyses were performed based on the presence/absence of bands representing fragments of DNA generated by random amplification. Similarity values between two of the populations were equivalent to those detected within a third, indicating the mixing of genetic material due to transplant between the two former localities. Similarities between samples of ChileanGracilaria andG. tenuistipitata from Sweden are considerably lower (0.45–0.53) than those between populations from Chile (0.74–0.88), confirming the existence of a single specific taxon,G. chilensis, in these three localities.     

Terrigenous sediment-dominated reef platform infilling: an unexpected precursor to reef island formation and a test of the reef platform size–island age model in the Pacific

Low-lying coral reef islands are considered highly vulnerable to climate change, necessitating an improved understanding of when and why they form, and how the timing of formation varies within and among regions. Several testable models have been proposed that explain inter-regional variability as a function of sea-level history and, more recently, a reef platform size model has been proposed from the Maldives (central Indian Ocean) to explain intra-regional (intra-atoll) variability. Here we present chronostratigraphic data from Pipon Island, northern Great Barrier Reef (GBR), enabling us to test the applicability of existing regional island evolution models, and the platform size control hypothesis in a Pacific context. We show that reef platform infilling occurred rapidly (~4–5 mm yr⁻¹) under a “bucket-fill” type scenario. Unusually, this infilling was dominated by terrigenous sedimentation, with platform filling and subsequent reef flat formation complete by ~5000 calibrated years BP (cal BP). Reef flat exposure as sea levels slowly fell post highstand facilitated a shift towards intertidal and subaerial-dominated sedimentation. Our data suggest, however, a lag of ~1500 yr before island initiation (at ~3200 cal BP), i.e. later than that reported from smaller and more evolutionarily mature reef platforms in the region. Our data thus support: (1) the hypothesis that platform size acts to influence the timing of platform filling and subsequent island development at intra-regional scales; and (2) the hypothesis that the low wooded islands of the northern GBR conform to a model of island formation above an elevated reef flat under falling sea levels.

     

Benzyl propionate synthesis by fed-batch esterification using commercial immobilized and lyophilized Cal B lipase

Bioprocess and Biosystems Engineering - In this work, a fed-batch approach was adopted to overcome propionic acid lipase inactivation effects in the benzyl propionate direct esterification mediated...     

Evaluating the genetic structure of wild and commercial red cusk-eel (Genypterus chilensis) populations through the development of novel microsatellite markers from a reference transcriptome

Molecular Biology Reports - The red cusk-eel (Genypterus chilensis) is a native Chilean species with a high-value market, with the potential to diversify Chilean aquaculture. The objective of this...     

Is allometry of sexual traits adaptive? A field test with territorial damselflies

Recent studies have linked static allometry of sexual traits to selective advantages, in terms of sexual selection. An underlying, yet untested, assumption is that the allometry of sexual traits confers higher mating success and/or survival. Here, we investigated whether the allometry of two sexual traits is related to male mating success and survival in two species of damselflies: wing size in Paraphlebia zoe and the red‐pigmented wing spot in Hetaerina americana. We used large field‐based data sets of marked‐recaptured animals, in which we recorded male mating success and survival. Both sexual traits exhibited hyperallometric patterns; however, allometry was not linked to either mating success or survival. These results indicate that, at least during the period of sexual competition, allometry does not seem to be adaptive. Although our results may only apply to our damselfly study subjects (which nevertheless would require further tests in different seasons and/or study sites), our findings should encourage researchers to evaluate at least whether the assumed adaptiveness of sexual trait allometry holds for their study animals. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 327–334.