Devil Declines and Catastrophic Cascades: Is Mesopredator Release of Feral Cats Inhibiting Recovery of the Eastern Quoll?

The eastern quoll (Dasyurus viverrinus) is a medium-sized Australian marsupial carnivore that has recently undergone a rapid and severe population decline over the 10 years to 2009, with no sign of recovery. This decline has been linked to a period of unfavourable weather, but subsequent improved weather conditions have not been matched by quoll recovery. A recent study suggested another mechanism: that declines in Tasmanian devil (Sarcophilus harrisii) populations, due to the spread of the fatal Devil Facial Tumour Disease, have released feral cats (Felis catus) from competitive suppression, with eastern quoll declines linked to a subsequent increase in cat sightings. Yet current evidence of intraguild suppression among devils, cats and quolls is scant and equivocal. We therefore assessed the influences of top-down effects on abundance and activity patterns among devils, feral cats and eastern quolls. Between 2011 and 2013, we monitored four carnivore populations using longitudinal trapping and camera surveys, and performed camera surveys at 12 additional sites throughout the eastern quoll’s range. We did not find evidence of a negative relationship between devil and cat abundance, nor of higher cat abundance in areas where devil populations had declined the longest. Cats did not appear to avoid devils spatially; however, there was evidence of temporal separation of cat and devil activity, with reduced separation and increasing nocturnal activity observed in areas where devils had declined the longest. Cats and quolls used the same areas, and there was no evidence that cat and quoll abundances were negatively related. Temporal overlap in observed cat and quoll activity was higher in summer than in winter, but this seasonal difference was unrelated to devil declines. We suggest that cats did not cause the recent quoll decline, but that predation of juvenile quolls by cats could be inhibiting low density quoll populations from recovering their former abundance through a ‘predator pit’ effect following weather-induced decline. Predation intensity could increase further should cats become increasingly nocturnal in response to devil declines.     

Reproductive Hormone-Dependent and -Independent Contributions to Developmental Changes in Kisspeptin in GnRH-Deficient Hypogonadal Mice

Kisspeptin is a potent activator of GnRH-induced gonadotropin secretion and is a proposed central regulator of pubertal onset. In mice, there is a neuroanatomical separation of two discrete kisspeptin neuronal populations, which are sexually dimorphic and are believed to make distinct contributions to reproductive physiology. Within these kisspeptin neuron populations, Kiss1 expression is directly regulated by sex hormones, thereby confounding the roles of sex differences and early activational events that drive the establishment of kisspeptin neurons. In order to better understand sex steroid hormone-dependent and -independent effects on the maturation of kisspeptin neurons, hypogonadal (hpg) mice deficient in GnRH and its downstream effectors were used to determine changes in the developmental kisspeptin expression. In hpg mice, sex differences in Kiss1 mRNA levels and kisspeptin immunoreactivity, typically present at 30 days of age, were absent in the anteroventral periventricular nucleus (AVPV). Although immunoreactive kisspeptin increased from 10 to 30 days of age to levels intermediate between wild type (WT) females and males, corresponding increases in Kiss1 mRNA were not detected. In contrast, the hpg arcuate nucleus (ARC) demonstrated a 10-fold increase in Kiss1 mRNA between 10 and 30 days in both females and males, suggesting that the ARC is a significant center for sex steroid-independent pubertal kisspeptin expression. Interestingly, the normal positive feedback response of AVPV kisspeptin neurons to estrogen observed in WT mice was lost in hpg females, suggesting that exposure to reproductive hormones during development may contribute to the establishment of the ovulatory gonadotropin surge mechanism. Overall, these studies suggest that the onset of pubertal kisspeptin expression is not dependent on reproductive hormones, but that gonadal sex steroids critically shape the hypothalamic kisspeptin neuronal subpopulations to make distinct contributions to the activation and control of the reproductive hormone cascade at the time of puberty.     

Delivery of Brain-Derived Neurotrophic Factor by 3D Biocompatible Polymeric Scaffolds for Neural Tissue Engineering and Neuronal Regeneration

Biopolymers are increasingly employed for neuroscience applications as scaffolds to drive and promote neural regrowth, thanks to their ability to mediate the upload and subsequent release of active molecules and drugs. Synthetic degradable polymers are characterized by different responses ranging from tunable distension or shrinkage to total dissolution, depending on the function they are designed for. In this paper we present a biocompatible microfabricated poly-ε-caprolactone (PCL) scaffold for primary neuron growth and maturation that has been optimized for the in vitro controlled release of brain-derived neurotrophic factor (BDNF). We demonstrate that the designed morphology confers to these devices an enhanced drug delivery capability with respect to monolithic unstructured supports. After incubation with BDNF, micropillared PCL devices progressively release the neurotrophin over 21 days in vitro. Moreover, the bioactivity of released BDNF is confirmed using primary neuronal cultures, where it mediates a consistent activation of BDNF signaling cascades, increased synaptic density, and neuronal survival. These results provide the proof-of-principle on the fabrication process of micropatterned PCL devices, which represent a promising therapeutic option to enhance neuronal regeneration after lesion and for neural tissue engineering and prosthetics.     

Modulation of the cell-mediated immune function by interferon α, β or γ can partially reverse the immunosuppression induced by human T-cell leukemia virus I in human cord blood cultures

Summary Infection with human T-cell leukemia virus type I (HTLV-I) is associated in vitro and in vivo with a remarkable depression of cell-mediated immune functions. In the present report it is shown that early events following virus-induced suppression of the cell-mediated immune response of freshly isolated cord blood mononuclear cells (CBL) infected with HTLV-I can be partially counteracted by treatment with interferons , or (IFN). All three types of IFN exerted a protective effect on CBL cultures exposed to the virus. This resulted in: (a) a reduced number of virus-positive cells until 4 weeks of culture; (b) delay in the clonal expansion of infected cells (IFN and ); (c) increased natural killer cell activity of CBL, 1 week post-infection (p.i.), mediated by IFN; (d) increase of allospecific recognition of infecting and priming HTLV-I donor MT-2 cells by CBL in a cytotoxic-T-lymphocyte-like response, mediated by IFN and particularly by IFN; (e) phenotype distribution of CBL subpopulations, tested 4 days p.i., more similar to that of non-infected CBL cultures.In contrast, the overall CBL proliferation, that is profoundly depressed during the first week p.i., was not restored by IFN treatments, suggesting that boosting of the cell-mediated killing induced by IFN might involve the maturation of undifferentiated precursor cells rather than stimulation of their proliferation. The improvement of the efficiency of the antiviral immune response induced by treatment with IFN is likely to contribute to the clearance of virus-positive cells during the early phase of infection. This would provide experimental evidence to support an immunopharmacological approach contributing to the conversion of HTLV-I carriers from positive to negative.     

Regulation of niemann-pick c1 gene expression by the 3'5'-cyclic adenosine monophosphate pathway in steroidogenic cells

The Niemann Pick-C1 (NPC-1) protein is essential for intracellular transport of cholesterol derived from low-density lipoprotein import in mammalian cells. The role of the protein kinase A (PKA) pathway in regulation of expression of the NPC-1 gene was investigated. NPC-1 promoter activity was induced by treatment with dibutryl cAMP (dbcAMP), alone or in combination with the cAMP response element (CRE) binding protein (CREB) overexpressed in adrenal Y-1 cells. When the catalytic subunit of PKA was overexpressed in Y-1 cells, there were similar increases in NPC-1 promoter activity in the presence of CREB. Responses were attenuated by blockade of the PKA pathway, and in the Kin-8 cell line deficient in PKA. Promoter deletion analysis revealed that this response was present in promoter fragments of 186 bp and larger but not present in the 121-bp fragment. Two promoter regions, one at -430 and one at -120 upstream of the translation initiation site, contained CRE consensus sequences. These bound recombinant CREB in EMSA, confirming their authenticity as CREB response elements. Promoters bearing mutations of both CRE displayed no response to dbcAMP. The orphan nuclear receptor, steroidogenic factor-1 (SF-1), was implicated in NPC-1 transactivation by the presence of SF-1 target sequence that formed a complex with recombinant SF-1 in EMSA. Furthermore, transfection of a plasmid that overexpressed SF-1 into ovarian granulosa cells increased promoter activity in response to dbcAMP, an effect abrogated by mutation of the SF-1 target sequence. Chromatin immunoprecipitation assays demonstrated that the CRE region of the endogenous and transfected NPC-1 promoter associated with both acetylated and phosphorylated histone H-3 and that this association was increased by dbcAMP treatment. Treatment with dbcAMP also increased the association of the CRE region of the promoter with CREB binding protein, which has histone acetyltransferase activity. Together, these results demonstrate a mechanism of regulation of NPC-1 expression by the cAMP-PKA pathway that includes PKA phosphorylation of CREB, recruitment of the coactivator CREB binding protein and the phosphorylation and acetylation of histone H-3 to transactivate the NPC-1 promoter.     

Space use and temporal partitioning of sympatric Tasmanian devils and spotted‐tailed quolls

Sympatric species can minimise interspecific competition by spatial avoidance or by altering their temporal activity to reduce encounter rates. The Tasmanian devil (Sarcophilus harrisii), the largest carnivorous marsupial, coexists with the smaller spotted‐tailed quoll (Dasyurus maculatus) in Tasmania, Australia. Quolls may be susceptible to interspecific competition from devils, because they utilise similar habitats, consume similar prey species and are displaced by devils at food sources. Such competition might cause quolls to spatially or temporally avoid devils. To investigate whether spatial or temporal avoidance occurred, we deployed GPS collars on sympatric devils and quolls and conducted a camera survey at a site in northwest Tasmania where the devil population was not affected by devil facial tumour disease. GPS tracking coincided with the lactation period when devils and quolls had young in dens and continued until weaning occurred. We found little spatial segregation of home range and core area placement between devils and quolls and among devils. Quolls showed more spatial segregation within the sexes than between them. Devils had larger home ranges than quolls. Male devils had larger home ranges than females, but there was no difference in home range size between the sexes of quolls. Females of both species travelled significantly further per night than did males. There was moderate temporal partitioning between the two species: devil activity peaked after dusk and devils remained active until the early morning, while quoll activity showed distinct peaks around dusk and dawn. In conclusion, quolls did not spatially avoid devils but moderate temporal partitioning occurred. It is plausible that quolls are active at different times of the diel cycle to reduce encountering devils, but further studies are needed to resolve the cause of this temporal partitioning.     

Evaluation of Relapse-Free Survival in T3N0 Colon Cancer: The Role of Chemotherapy,a Multicentric Retrospective Analysis

Background

Adjuvant chemotherapy (AC) in Stage II Colon Cancer (CC) is still under debate. Choice should be based on patients and disease characteristics. According to guidelines AC should be considered in high-risk T3N0 patients. No data are available for better option in low-risk patients. The aim of the study is to retrospectively evaluate relapse-free survival (RFS) and disease-free survival (DFS) according to treatment received in T3N0 CC.

Methods

RFS and DFS are evaluated with Kaplan-Meier method. Multivariate Cox proportional hazard model was developed using stepwise regression, enter limit and remove limit were p = 0.10 and p = 0.15, respectively.

Results

834 patients with T3N0 CC were recruited. Median age was 69 (29–93), M/F 463/371, 335 low-risk patients (40.2%), 387 high-risk (46.4%), 112 unknown (13.4%); 127 (15.2%) patients showed symptoms at diagnosis. Median sampled lymph nodes were 15 (1–76); 353 (42.3%) patients were treated with AC. Median follow up was 5 years (range 3–24). The 5-years RFS was 78.4% and the 5-years DFS was 76.7%. At multivariate analysis symptoms, lymph nodes, and adjuvant chemotherapy were prognostic factors for RFS. AC is prognostic factor for all endpoints.In low-risk group 5-years RFS was 87.3% in treated patients and 74.7% in non-treated patients (p 0.03); in high-risk group was respectively 82.7% and 71.4% (p 0.005).

Conclusions

Data confirmed the role of known prognostic factors and suggest the relevance of adjuvant chemotherapy also in low-risk stage II T3N0 CC patients. However, the highest risk in low-risk subgroup should be identified to be submitted to AC.     

Synthesis of structurally simplified analogues of aplidinone A,a pro-apoptotic marine thiazinoquinone

The synthesis of analogues of aplidinone A (7), a prenylated quinone isolated from the Mediterranean ascidian Aplidium conicum, has been performed. This work not only allowed confirming the structural assignment of aplidinone A, previously made with the support of GIAO shielding calculations, but, above all, made a series of structurally related quinone derivatives (compounds 8–13 and the natural metabolite) available for a screening in vitro for cytotoxic and pro-apoptotic activity and for SAR studies. The study evidenced one of the synthetic analogues (11) as a potent cytotoxic and pro-apoptotic agent against several tumor cell lines which also inhibits the TNFα-induced NF-κB activation in a human leukemia T cell line. This exemplifies the potential of a natural product to qualify as lead structure for medicinal chemistry campaigns, affording simplified analogues with better bioactivity and easier to synthesize.     

Genetic strategies for improving hyaluronic acid production in recombinant bacterial culture

Hyaluronic acid (HA) is a biopolymer of repeating units of glucuronic acid and N-acetylglucosamine. Its market was valued at USD 8.9 billion in 2019. Traditionally, HA has been obtained from rooster comb-like animal tissues and fermentative cultures of attenuated pathogenic streptococci. Various attempts have been made to engineer a safe micro-organism for HA synthesis; however, the HA titres obtained from these attempts are in general still lower than those achieved by natural, pathogenic producers. In this scenario, ways to increase HA molecule length and titres in already constructed strains are gaining attention in the last years, but no recent publication has reviewed the main genetic strategies applied to improve HA production on heterologous hosts. In light of that, we hereby compile the advances made in the engineering of micro-organisms to improve HA synthesis.