A test for prorelaxin-processing enzymes using unmodified peptide substrates

Summary Relaxin is a member of the insulin family of proteins. It is produced principally in ovarian cells by processing of its larger precursor, prorelaxin. The enzymes responsible for conversion of prorelaxin to the mature hormone have not yet been elucidated. A rapid and convenient test has been developed to detect prorelaxin-processing enzymes in porcine ovary extracts. Unmodified peptide substrates, which represent the two prorelaxin-processing sites, were chemically synthesised and nanomolar amounts of these substrates were incubated in solution with enzyme preparations. The resultant fragments were resolved using high performance liquid chromatography or capillary electrophoresis and identified by their retention times compared with synthetic standards. This test has been successfully used to identify and characterise a candidate prorelaxin-processing enzyme from chromatographically fractionated porcine ovary extracts. The enzyme was found to be a serine protease with preference for cleavage after tetrabasic sequences and with optimal activity at pH 5.5–6.5.     

Ethnobotanical survey of cooling herbal drinks from southern China

In terms of scientific activities generally and ethnobiological pursuits in particular, North Korea, officially known as the Democratic People’s Republic of Korea, is an almost blank entity on the quilt of global research. During a sabbatical semester at Pyongyang University of Science and Technology the author used this opportunity to gather some information on the uses of insect and other terrestrial arthropods as human food and components of traditional healing methods in that country. Despite the widely publicised shortcomings in the supply of food stuffs to the population of North Korea, insects are not generally seen as a source of food worthy of exploitation. However, the therapeutic use of insects, centipedes and scorpions to treat illnesses as diverse as the common cold, skin rashes, constipation, dysentery, nervous prostration, whooping cough, osteomyelitis, tetanus, and various forms of cancer is apparently still popular. The arthropods used therapeutically are credited with anti-inflammatory, immunological and other health-promoting effects, because they are said to contain hormones, steroids, lipids and plant-derived alkaloids, all of which capable of exerting their effects on the human body.     

p53 is required for nuclear but not mitochondrial DNA damage-induced degeneration

While the consequences of nuclear DNA damage have been well studied, the exact consequences of acute and selective mitochondrial DNA (mtDNA) damage are less understood. DNA damaging chemotherapeutic drugs are known to activate p53-dependent apoptosis in response to sustained nuclear DNA damage. While it is recognized that whole-cell exposure to these drugs also damages mtDNA, the specific contribution of mtDNA damage to cellular degeneration is less clear. To examine this, we induced selective mtDNA damage in neuronal axons using microfluidic chambers that allow for the spatial and fluidic isolation of neuronal cell bodies (containing nucleus and mitochondria) from the axons (containing mitochondria). Exposure of the DNA damaging drug cisplatin selectively to only the axons induced mtDNA damage in axonal mitochondria, without nuclear damage. We found that this resulted in the selective degeneration of only the targeted axons that were exposed to DNA damage, where ROS was induced but mitochondria were not permeabilized. mtDNA damage-induced axon degeneration was not mediated by any of the three known axon degeneration pathways: apoptosis, axon pruning, and Wallerian degeneration, as Bax-deficiency, or Casp3-deficiency, or Sarm1-deficiency failed to protect the degenerating axons. Strikingly, p53, which is essential for degeneration after nuclear DNA damage, was also not required for degeneration induced with mtDNA damage. This was most evident when the p53-deficient neurons were globally exposed to cisplatin. While the cell bodies of p53-deficient neurons were protected from degeneration in this context, the axons farthest from the cell bodies still underwent degeneration. These results highlight how whole cell exposure to DNA damage activates two pathways of degeneration; a faster, p53-dependent apoptotic degeneration that is triggered in the cell bodies with nuclear DNA damage, and a slower, p53-independent degeneration that is induced with mtDNA damage.Subject terms: Cell biology, Neuroscience     

Conservation genetics of the central newt (Notophthalmus viridescens) in Iowa: the importance of a biogeographic framework

In light of global declines in amphibian populations, genetic data have become increasingly important for understanding population structure and for revealing hidden diversity. At the species level, Notophthalmus viridescens is an IUCN species of “least concern”, but the subspecies N. v. louisianensis (central newt) is listed as “threatened” in Iowa, a state on the western periphery of the species range. Genetic data were collected from 282 N. v. louisianensis from 14 sites in Iowa. Sequences from 1,054 nucleotides of mitochondrial DNA from Iowa newts revealed unexpected diversity in the form of two major haplotype groups that are not sister clades, with southern Iowa N. v. louisianensis being more closely related to N. v. piaropicola (peninsula newt) from Florida than to consubspecifics in Iowa. Sequence differentiation indicates that the two lineages of newts present in Iowa diverged near the beginning of the Pleistocene. Northern and southern Iowa haplotypes were found together at one site, indicating an opportunity for hybridization near Remington’s biogeographic suture zone 1, a hotspot for hybridization in other species. Three microsatellite loci provided additional evidence for distinctness of northern and southern Iowa newt populations. This study highlights the relevance of historical biogeography to conservation, as management strategies for N. v. louisianensis in Iowa must reflect previously unrecognized diversity in this species. Nuclear and mitochondrial data indicate genetic isolation of nearby populations on the same drainage, and field data suggest the decline of one study population, emphasizing the need for identification and protection of newt breeding sites in Iowa.     

A review of symbiotic gorgonian research in the western Atlantic and Caribbean with recommendations for future work

Coral Reefs - While scleractinian coral populations continue to diminish throughout the Caribbean, gorgonian corals are showing signs of resilience and in some areas are thriving. Despite their...     

Nucleotide excision repair efficiency in quiescent human fibroblasts is modulated by circadian clock

The efficiency of Nucleotide Excision Repair (NER)process is crucial for maintaining genomic integrity because in many organisms, including humans, it represents the only system able to repair a wide range of DNA damage. The aim of the work was to investigate whether the efficiency of the repair of photoproducts induced by UV-light is affected by the circadian phase at which irradiation occurred. NER activity has been analyzed in human quiescent fibroblasts (in the absence of the cell cycle effect), in which circadian rhythmicity has been synchronized with a pulse of dexamethasone. Our results demonstrate that both DNA damage induction and repair efficiency are strictly dependent on the phase of the circadian rhythm at which the cells are UV-exposed. Furthermore, the differences observed between fibroblasts irradiated at different circadian times (CTs) are abolished when the clock is obliterated. In addition, we observe that chromatin structure is regulated by circadian rhythmicity. Maximal chromatin relaxation occurred at the same CT when photoproduct formation and removal were highest. Our data suggest that the circadian clock regulates both the DNA sensitivity to UV damage and the efficiency of NER by controlling chromatin condensation mainly through histone acetylation.     

A transitory signaling center controls timing of primordial germ cell differentiation

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