Stoppen of niet stoppen, dat is de vraag

in deze scriptie wordt onderzoek gedaan naar de invloed van menselijk gedrag op desinvesteringsbeslissingen. Daarbij wordt mn aandacht gegeven aan de vraag of de richting die de organisatie opgaat van invloed is op het tijdig nemen van desinvesteringsbeslissingen

Historical development of the survivorship of zoo rhinoceroses—A comparative historical analysis

Zoo animal husbandry is a skill that should be developing constantly. In theory, this should lead to an improvement of zoo animal survivorship over time. Additionally, it has been suggested that species that are at a comparatively higher risk of extinction in their natural habitats (in situ) might also be more difficult to keep under zoo conditions (ex situ). Here, we assessed these questions for three zoo‐managed rhinoceros species with different extinction risk status allocated by the IUCN: the “critically endangered” black rhino (Diceros bicornis), the “vulnerable” greater one‐horned (GOH) rhino (Rhinoceros unicornis), and the “near threatened” white rhino (Ceratotherium simum). Comparing zoo animals ≥1 year of age, the black rhino had the lowest and the white rhino the highest survivorship, in congruence with their extinction risk status. Historically, the survivorship of both black and white rhino in zoos improved significantly over time, whereas that of GOH rhino stagnated. Juvenile mortality was generally low and decreased even further in black and white rhinos over time. Together with the development of population pyramids, this shows increasing competence of the global zoo community to sustain all three species. Compared to the continuously expanding zoo population of GOH and white rhinos, the zoo‐managed black rhino population has stagnated in numbers in recent years. Zoos do not only contribute to conservation by propagating ex situ populations, but also by increasing species‐specific husbandry skills. We recommend detailed research to understand specific factors responsible for the stagnation but also the general improvement of survivorship of zoo‐managed rhinos

Reproductive non-seasonality in rhinoceroses: A review of the in-situ literature and birth records of ex-situ institutions

Mammals whose breeding activity is triggered by seasonal photoperiodic cues typically maintain seasonal reproduction in zoos, with births accumulating to various degrees in spring. For zoo-kept rhinoceroses, accumulation of births in autumn has been suggested, which would make this group unusual. We compare birthing (and hence conception) patterns of free-ranging rhinoceros populations from the scientific literature with those of the global zoo populations based on birth data available from Species360, to facilitate deductions on the cues that trigger rhinoceros reproduction. The patterns do not indicate a photoperiodic element in rhinoceros reproduction but suggest suppression of conception in free-ranging populations at times of resource scarcity. This is not evident in zoos. However, a slight accumulation of autumn births, due to a slight reduction in births in spring, is visible in the zoo populations. Given rhinoceros gestation periods, this is linked to reduced conceptions in November–December. The most parsimonious interpretation is management-related, as has been suggested (Roth 2006, Int. Zoo Yb. 40(1): 130–143): not all facilities are prepared to allow mating at times when outdoor husbandry is reduced due to weather restrictions. Given the long interbirth intervals of rhinoceroses, missed conception opportunities of 1–2 months are unlikely to affect population demographics. Nevertheless, detailed recording of approaches to facilitate mating during winter months by those zoos that achieve this may increase the general skill of rhinoceros management

Group composition impacts reproductive output and population viability in captive white rhinoceros

Captive breeding programmes can play an important role in the conservation of species threatened with extinction in the wild. White rhinoceros, Ceratotherium simum, have suffered drastic declines due to illegal poaching across their range, and captive populations have the potential to safeguard this species from extinction. However, white rhinoceros birth rates in captivity have been extremely low, and there is substantial variation in breeding success between different institutions. A better understanding of the factors limiting their reproduction in captivity could improve their breeding management and conservation potential. This study used studbook data (n = 467) and comparisons with wild populations in Kenya (n = 236) to assess the breeding performance and viability of the European captive southern white rhinoceros, Ceratotherium simum simum, population. Our results show that the European population is declining 2% annually under current demographic parameters. On average, just 10% of females calved annually, in comparison to almost 40% across wild populations. To become self-sustaining, this must increase to a minimum of 17%, though reaching this target may lead to additional management challenges. Further analyses using studbook (n = 134 individuals) and multi-institutional questionnaire data (n = 20 institutions) suggest that modifying the social structure of captive groups could improve female breeding success. Institutions housing larger groups had proportionally greater breeding success, and females were more likely to copulate if housed with another breeding female, and more receptive to bulls if housed in a group with a lower mean age. These findings highlight the importance of considering social conditions in captive breeding programmes, particularly for species with complex social systems and low reproductive rates

Complicated Odontogenic Infections at 2 District Hospitals in Tonkolili District, Sierra Leone:Protocol for a Prospective Observational Cohort Study (DELAY)

BACKGROUND: Deficits in global oral health care are paramount, and complications of odontogenic infections constitute a considerable global health problem, particularly in low-income countries. A high mortality rate has been observed for patients who have been admitted with complicated odontogenic infections to our facilities in Tonkolili District, Sierra Leone, although exact data have not been published yet. Data regarding who in this region is at risk and why are lacking. OBJECTIVE: The Dental Abscess Study (DELAY) aims to prospectively investigate morbidity and mortality from complicated dental abscesses and to analyze patients’ characteristics and microbial findings to examine predisposing factors for poor outcomes. In particular, the incidence and the clinical and microbial characteristics of complicated odontogenic infections, as well as the sociodemographic data and comorbidities of affected patients, will be studied to develop improved management algorithms based on circumstance-specific factors. METHODS: Patients who present with complicated dental infections requiring hospital admission in Masanga Hospital or Lion Heart Medical Centre will be consecutively selected for possible inclusion in the study (starting on September 4, 2021) over a study period of 1 year, and individual routine follow-ups will be conducted at least 3 months after discharge. The results of standardized questionnaires will be obtained, and clinical measurements as well as medical photos will be taken. Standard laboratory tests (eg, full blood count and HIV status tests) will be performed, and pus specimens will be examined. Local treatment guidelines will be adhered to, and data on medical and surgical treatment as well as data on outcomes will be collected. The study results will be reported according to the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) criteria. Routine follow-ups will take place at 1 and 3 months postdischarge. RESULTS: The DELAY protocol was endorsed by the Masanga Medical Research Unit’s Scientific Review Committee on June 16, 2021, and ethical approval was granted on July 5, 2021, by the Sierra Leone National Ethics Committee. The funding of the budgeted study costs was approved by Dental Health International Netherlands in August 2021. The projected start date of data collection was September 4, 2021, and the study period will most likely last for 1 year. As such, data collection is expected to be complete in November 2022. CONCLUSIONS: The aim of our prospective observational cohort study is to gain more knowledge about complicated odontogenic infections in Tonkolili District, Sierra Leone, to further improve treatment strategies. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/3367

Rapid detection of SMARCB1 sequence variation using high resolution melting

Background : Rhabdoid tumors are rare cancers of early childhood arising in the kidney, central nervous system and other organs. The majority are caused by somatic inactivating mutations or deletions affecting the tumor suppressor locus SMARCB1 [OMIM 601607]. Germ-line SMARCB1 inactivation has been reported in association with rhabdoid tumor, epitheloid sarcoma and familial schwannomatosis, underscoring the importance of accurate mutation screening to ascertain recurrence and transmission risks. We describe a rapid and sensitive diagnostic screening method, using high resolution melting (HRM), for detecting sequence variations in SMARCB1. Methods : Amplicons, encompassing the nine coding exons of SMARCB1, flanking splice site sequences and the 5\u27 and 3\u27 UTR, were screened by both HRM and direct DNA sequencing to establish the reliability of HRM as a primary mutation screening tool. Reaction conditions were optimized with commercially available HRM mixes. Results : The false negative rate for detecting sequence variants by HRM in our sample series was zero. Nine amplicons out of a total of 140 (6.4%) showed variant melt profiles that were subsequently shown to be false positive. Overall nine distinct pathogenic SMARCB1 mutations were identified in a total of 19 possible rhabdoid tumors. Two tumors had two distinct mutations and two harbored SMARCB1 deletion. Other mutations were nonsense or frame-shifts. The detection sensitivity of the HRM screening method was influenced by both sequence context and specific nucleotide change and varied from 1: 4 to 1:1000 (variant to wild-type DNA). A novel method involving digital HRM, followed by re-sequencing, was used to confirm mutations in tumor specimens containing associated normal tissue. Conclusions : This is the first report describing SMARCB1 mutation screening using HRM. HRM is a rapid, sensitive and inexpensive screening technology that is likely to be widely adopted in diagnostic laboratories to facilitate whole gene mutation screening

Strand invasion by HLTF as a mechanism for template switch in fork rescue.

Stalling of replication forks at unrepaired DNA lesions can result in discontinuities opposite the damage in the newly synthesized DNA strand. Translesion synthesis or facilitating the copy from the newly synthesized strand of the sister duplex by template switching can overcome such discontinuities. During template switch, a new primer-template junction has to be formed and two mechanisms, including replication fork reversal and D-loop formation have been suggested. Genetic evidence indicates a major role for yeast Rad5 in template switch and that both Rad5 and its human orthologue, Helicase-like transcription factor (HLTF), a potential tumour suppressor can facilitate replication fork reversal. This study demonstrates the ability of HLTF and Rad5 to form a D-loop without requiring ATP binding and/or hydrolysis. We also show that this strand-pairing activity is independent of RAD51 in vitro and is not mechanistically related to that of another member of the SWI/SNF family, RAD54. In addition, the 3'-end of the invading strand in the D-loop can serve as a primer and is extended by DNA polymerase. Our data indicate that HLTF is involved in a RAD51-independent D-loop branch of template switch pathway that can promote repair of gaps formed during replication of damaged DNA

Escherichia coli RNA polymerase-associated SWI/SNF protein RapA: evidence for RNA-directed binding and remodeling activity

Helicase-like SWI/SNF proteins are present in organisms belonging to distant kingdoms from bacteria to humans, indicating that they perform a very basic and ubiquitous form of nucleic acid management; current studies associate the activity of SWI/SNF proteins with remodeling of DNA and DNA–protein complexes. The bacterial SWI/SNF homolog RapA—an integral part of the Escherichia coli RNA polymerase complex—has been implicated in remodeling post-termination DNA–RNA polymerase–RNA ternary complexes (PTC), however its explicit nucleic acid substrates and mechanism remain elusive. Our work presents evidence indicating that RNA is a key substrate of RapA. Specifically, the formation of stable RapA–RNA intermediates in transcription and other, independent lines of evidence presented herein indicate that RapA binds and remodels RNA during transcription. Our results are consistent with RapA promoting RNA release from DNA–RNA polymerase–RNA ternary complexes; this process may be accompanied by the destabilization of non-canonical DNA–RNA complexes (putative DNA–RNA triplexes). Taken together, our data indicate a novel RNA remodeling activity for RapA, a representative of the SWI/SNF protein superfamily