The Winding Road to Discovering the Link between Genetic Material and DNA

This is an account of the three-centuries long journey to the discovery of the link between DNA and the transformation principle of heredity beginning with the discovery of the cell in 1665 and leading up to the 1953 discovery of the genetic code and the structure of DNA.  This account also illustrates the way science works and how scientists do science as well as the fact that scientists are also subject to the same human foibles and short-comings as people in any field of endeavor.  Their use of the scientific method helps them find the path back from false starts and erroneous conclusions but does not assure a smooth progression toward the truth.  What emerges from this example is the scientists’ search for explanations based on empirical evidence, with the goal of trying to disapprove, rather than prove, a given theory and explanation.  As scientific knowledge increases, answers to scientific questions may become outdated, or they may generate a new set of questions that require new ways of thinking and conducting experiments.  Science educators have already recognized the value of historical materials and events in fostering an accurate understanding of science and in achieving desirable, positive and realistic attitudes toward science and in developing scientifically aware citizens. This is simple because the history of science can provide a vital background for students, detailing how science and scientists work and how scientific knowledge is created, validated, and influenced. However, desirable attitudes and behaviors toward science are not likely to be achieved unless history of science is learned and appreciated by all young citizens. Thus, there is a need for educators to involve, investigate, and explore the application of historical science and to show how this can contribute to accurately and explicitly show what science is, how it works, how scientists operate as a social group and how human societies direct and react to scientific endeavors both locally and globally (McComas, 2015, Cherif, 1988, Klopfer, 1969). And it is here where the history of science, the nature of science and how scientists do science is of enduring interest to us as well as to many educators in the scientific community. For those who might use this essay as classroom reading material, we provide a set of questions as an appendix that teachers and faculty may use to reinforce understanding of the essay.   Key Words: DNA, Genetic Code, Scientific inquiry, scientific discovery, Scientific method, Empirical evidence, Theory and explanation, How science works, Humanity and civic engagemen

The radial curvature of an end that makes eigenvalues vanish in the essential spectrum II

Under the quadratic-decay-conditions of the radial curvatures of an end, we shall derive growth estimates of solutions to the eigenvalue equation and show the absence of eigenvalues.Comment: "$\ge$" in the conditions $(*_4)$ and $(*_5)$ should be replaced by "$>$". $\gamma \ge \frac{n-1}{2}(b-a)$ in the conclusion of Theorem 1.3 should be replaced by $\gamma > \frac{n-1}{2}(b-a)$; trivial miss-calculatio

Altruism can proliferate through group/kin selection despite high random gene flow

The ways in which natural selection can allow the proliferation of cooperative behavior have long been seen as a central problem in evolutionary biology. Most of the literature has focused on interactions between pairs of individuals and on linear public goods games. This emphasis led to the conclusion that even modest levels of migration would pose a serious problem to the spread of altruism in group structured populations. Here we challenge this conclusion, by analyzing evolution in a framework which allows for complex group interactions and random migration among groups. We conclude that contingent forms of strong altruism can spread when rare under realistic group sizes and levels of migration. Our analysis combines group-centric and gene-centric perspectives, allows for arbitrary strength of selection, and leads to extensions of Hamilton's rule for the spread of altruistic alleles, applicable under broad conditions.Comment: 5 pages, 2 figures. Supplementary material with 50 pages and 26 figure

Tandem quadruplication of HMA4 in the zinc (Zn) and cadmium (Cd) hyperaccumulator noccaea caerulescens

Zinc (Zn) and cadmium (Cd) hyperaccumulation may have evolved twice in the Brassicaceae, in Arabidopsis halleri and in the Noccaea genus. Tandem gene duplication and deregulated expression of the Zn transporter, HMA4, has previously been linked to Zn/Cd hyperaccumulation in A. halleri. Here, we tested the hypothesis that tandem duplication and deregulation of HMA4 expression also occurs in Noccaea. A Noccaea caerulescens genomic library was generated, containing 36,864 fosmid pCC1FOSTM clones with insert sizes ~20–40 kbp, and screened with a PCR-generated HMA4 genomic probe. Gene copy number within the genome was estimated through DNA fingerprinting and pooled fosmid pyrosequencing. Gene copy numbers within individual clones was determined by PCR analyses with novel locus specific primers. Entire fosmids were then sequenced individually and reads equivalent to 20-fold coverage were assembled to generate complete whole contigs. Four tandem HMA4 repeats were identified in a contiguous sequence of 101,480 bp based on sequence overlap identities. These were flanked by regions syntenous with up and downstream regions of AtHMA4 in Arabidopsis thaliana. Promoter-reporter b-glucuronidase (GUS) fusion analysis of a NcHMA4 in A. thaliana revealed deregulated expression in roots and shoots, analogous to AhHMA4 promoters, but distinct from AtHMA4 expression which localised to the root vascular tissue. This remarkable consistency in tandem duplication and deregulated expression of metal transport genes between N. caerulescens and A. halleri, which last shared a common ancestor >40 mya, provides intriguing evidence that parallel evolutionary pathways may underlie Zn/Cd hyperaccumulation in Brassicaceae

Prognostic value of radiological recurrence patterns in ovarian cancer

Objective: To study the prognostic value of CT assessed recurrence patterns on survival outcomes in women with epithelial ovarian cancer. Methods: CT scans were systematically re-evaluated on predefined anatomical sites for the presence of tumor in all 89 patients diagnosed with epithelial ovarian cancer between January 2008 and December 2013 who underwent cytoreductive surgery at our institution and developed a recurrence. A Cox proportional hazard analysis was used to test the effect of recurrence patterns on survival. Results: The median survival time for patients grouped as predominantly intraperitoneal (n = 62), hematogenous (n = 13) or lymphatic (n = 14) recurrence was 25.8 (95% CI 18.4–33.2), 27.6 (95% CI 18.5–36.6) and 52.9 months (95% CI 42.1–63.7), respectively. Univariate Cox regression analysis identified the following prognostic factors: lymphatic recurrence pattern (HR 0.42, 95% CI 0.21–0.85), ascites at diagnosis (HR 2.35, 95% CI 1.46–3.79), residual tumor at initial surgery (HR 2.16, 95% CI 1.36–3.44) and FIGO stage (I–IIIB: HR 0.59, 95% CI 0.33–1.06). The median time to recurrence was 19.5 month for patients after complete debulking surgery, 13.1 months for patients with residual disease ≤1 cm and 8.2 months for patients with residual disease >1 cm after surgery (P < 0.001). No differences in recurrence patterns between patients with complete and incomplete surgery were found. Conclusions: Prolonged survival rates were found in ovarian cancer patients with a predominantly lymphatic recurrence compared to patients with a predominantly peritoneal or hematogenous recurrence. Completeness of surgery was associated with time to recurrence. Classification of recurrence patterns can help counsel patients on their prognosis at the time of recurrence

Sense and nonsense in sensors

Continuous subcutaneous glucose monitoring (CGM) is a developing technology in the treatment of diabetes mellitus. The first randomised controlled trials on its efficacy have been performed. In several studies, CGM lowered HbA1c in adult patients with suboptimally controlled type 1 diabetes mellitus, when selecting compliant patients who tolerate the device. However, as a preventive tool for hypoglycaemia, CGM has not fulfilled the great expectations. Increasing reimbursement of CGM is expected in the near future, awaiting studies on cost-effectiveness

A Screening Tool to Quickly Identify Movement Disorders in Patients with Inborn Errors of Metabolism

Background: Movement disorders are frequent in patients with inborn errors of metabolism (IEMs) but poorly recognized, particularly by nonmovement disorder specialists. We propose an easy‐to‐use clinical screening tool to help recognize movement disorders. Objective: The aim is to develop a user‐friendly rapid screening tool for nonmovement disorder specialists to detect moderate and severe movement disorders in patients aged ≥4 years with IEMs. Methods: Videos of 55 patients with different IEMs were scored by experienced movement disorder specialists (n = 12). Inter‐rater agreements were determined on the presence and subtype of the movement disorder. Based on ranking and consensus, items were chosen to be incorporated into the screening tool. Results: A movement disorder was rated as present in 80% of the patients, with a moderate inter‐rater agreement (κ =0.420, P < 0.001) on the presence of a movement disorder. When considering only moderate and severe movement disorders, the inter‐rater agreement increased to almost perfect (κ = 0.900, P < 0.001). Dystonia was most frequently scored (27.3%) as the dominant phenotype. Treatment was mainly suggested for patients with moderate or severe movement disorders. Walking, observations of the arms, and drawing a spiral were found to be the most informative tasks and were included in the screening tool. Conclusions: We designed a screening tool to recognize movement disorders in patients with IEMs. We propose that this screening tool can contribute to select patients who should be referred to a movement disorder specialist for further evaluation and, if necessary, treatment of the movement disorder. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society

A Quantitative Test of Hamilton's Rule for the Evolution of Altruism

A study of experimental evolution in simulated groups of foraging robots demonstrates that their propensity to behave altruistically depends on their genetic relatedness (similarity), and the costs and benefits associated with altruistic behavior

Identification of metabolic pathways influenced by the G-protein coupled receptors GprB and GprD in Aspergillus nidulans

Heterotrimeric G-protein-mediated signaling pathways play a pivotal role in transmembrane signaling in eukaryotes. Our main aim was to identify signaling pathways regulated by A. nidulans GprB and GprD G-protein coupled receptors (GPCRs). When these two null mutant strains were compared to the wild-type strain, the DeltagprB mutant showed an increased protein kinase A (PKA) activity while growing in glucose 1% and during starvation. In contrast, the DeltagprD has a much lower PKA activity upon starvation. Transcriptomics and (1)H NMR-based metabolomics were performed on two single null mutants grown on glucose. We noted modulation in the expression of 11 secondary metabolism gene clusters when the DeltagprB and DeltagprD mutant strains were grown in 1% glucose. Several members of the sterigmatocystin-aflatoxin gene cluster presented down-regulation in both mutant strains. The genes of the NR-PKS monodictyphenone biosynthesis cluster had overall increased mRNA accumulation in DeltagprB, while in the DeltagprD mutant strain the genes had decreased mRNA accumulation. Principal component analysis of the metabolomic data demonstrated that there was a significant metabolite shift in the DeltagprD strain. The (1)H NMR analysis revealed significant expression of essential amino acids with elevated levels in the DeltagprD strain, compared to the wild-type and DeltagprB strains. With the results, we demonstrated the differential expression of a variety of genes related mainly to secondary metabolism, sexual development, stress signaling, and amino acid metabolism. We propose that the absence of GPCRs triggered stress responses at the genetic level. The data suggested an intimate relationship among different G-protein coupled receptors, fine-tune regulation of secondary and amino acid metabolisms, and fungal development