How immunocontraception can contribute to elephant management in small, enclosed reserves: Munyawana population as a case study

Immunocontraception has been widely used as a management tool to reduce population growth in captive as well as wild populations of various fauna. We model the use of an individual-based rotational immunocontraception plan on a wild elephant, Loxodonta africana, population and quantify the social and reproductive advantages of this method of implementation using adaptive management. The use of immunocontraception on an individual, rotational basis stretches the inter-calving interval for each individual female elephant to a management-determined interval, preventing exposing females to unlimited long-term immunocontraception use (which may have as yet undocumented negative effects). Such rotational immunocontraception can effectively lower population growth rates, age the population, and alter the age structure. Furthermore, such structured intervention can simulate natural process such as predation or episodic catastrophic events (e.g., drought), which regulates calf recruitment within an abnormally structured population. A rotational immunocontraception plan is a feasible and useful elephant population management tool, especially in a small, enclosed conservation area. Such approaches should be considered for other long-lived, social species in enclosed areas where the long-term consequences of consistent contraception may be unknown.     

Metabolite variation in the lettuce gene pool: towards healthier crop varieties and food

Introduction

Lettuce (Lactuca sativa L.) is generally not specifically acknowledged for its taste and nutritional value, while its cultivation suffers from limited resistance against several pests and diseases. Such key traits are known to be largely dependent on the ability of varieties to produce specific phytochemicals.

Objectives

We aimed to identify promising genetic resources for the improvement of phytochemical composition of lettuce varieties.

Methods

Phytochemical variation was investigated using 150 Lactuca genebank accessions, comprising a core set of the lettuce gene pool, and resulting data were related to available phenotypic information.

Results

A hierarchical cluster analysis of the variation in relative abundance of 2026 phytochemicals, revealed by untargeted metabolic profiling, strongly resembled the known lettuce gene pool structure, indicating that the observed variation was to a large extent genetically determined. Many phytochemicals appeared species-specific, of which several are generally related to traits that are associated with plant health or nutritional value. For a large number of phytochemicals the relative abundance was either positively or negatively correlated with available phenotypic data on resistances against pests and diseases, indicating their potential role in plant resistance. Particularly the more primitive lettuces and the closely related wild relatives showed high levels of (poly)phenols and vitamin C, thus representing potential genetic resources for improving nutritional traits in modern crop types.

Conclusion

Our large-scale analysis of phytochemical variation is unprecedented in lettuce and demonstrated the ample availability of suitable genetic resources for the development of improved lettuce varieties with higher nutritional quality and more sustainable production.

     

Toward functional genomics of flow-induced outward remodeling of resistance arteries

In resistance-sized arteries, a chronic increase in blood flow leads to increases in arterial structural luminal diameter and arterial wall mass. In this review, we summarize recent evidence that outward remodeling of resistance arteries 1) can help maintain and restore tissue perfusion, 2) is not intimately related to flow-induced vasodilatation, 3) involves transient dedifferentiation and turnover of arterial smooth muscle cells, and 4) is preceded by increased expression of matricellular proteins, which have been shown to promote disassembly of focal adhesion sites. Studies of experimental and physiological resistance artery remodeling involving differential gene expression analyses and the use of knockout and transgenic mouse models can help unravel the mechanisms of outward remodeling.     

Male sex drive and the masculinization of the genome

Charles Darwin remarked that "males, with their superior strength, pugnacity, armaments, unwieldly passion and love songs, are almost always the more active and most often, the initiators of sexual interactions". Here, we propose that such male sex drive directly impacts the genome by leading to its progressive masculinization--genes that possess sex-specific effects on male fitness accumulate to a much greater extent and are generally more diverged. The larger proportion of male versus female fitness modifiers in combination with stronger sexual selection may generate evolutionary signatures such as a greater sensitivity to male sterility and a paucity of X-linked male-specific genes. Male sex-drive theory complements the female-choice theory of sexual selection and allows for the genetic variation of costly sexual traits to be continuously replenished.     

Dose-dependent effects of UVB-induced skin carcinogenesis in hairless p53 knockout mice

Exposure to (solar) UVB radiation gives rise to mutations in the p53 tumor suppressor gene that appear to contribute to the earliest steps in the molecular cascade towards human and murine skin cancer. To examine in more detail the role of p53, we studied UVB-induced carcinogenesis in hairless p53 knock-out mice. The early onset of lymphomas as well as early wasting of mice interfered with the development of skin tumors in p53 null-mice. The induction of skin tumors in the hairless p53+/- mice was accomplished by daily exposure to two different UV-doses of approximately 450 J/m2 and 900 J/m2 from F40 lamps corresponding to a fraction of about 0.4 and 0.8 of the minimal edemal dose. Marked differences in skin carcinogenesis were observed between the p53+/- mice and their wild type littermates. Firstly, at 900 J/m2, tumors developed significantly faster in the heterozygotes than in wild types, whereas at 450 J/m2 there was hardly any difference, suggesting that only at higher damage levels loss of one functional p53 allele is important. Secondly, a large portion (25%) of skin tumors in the heterozygotes were of a more malignant, poorly differentiated variety of squamous cell carcinomas, i.e. spindle cell carcinomas, a tumor type that was rarely observed in daily UV exposed wild type hairless mice. Thirdly, the p53 mutation spectrum in skin tumors in heterozygotes is quite different from that in wild types. Together these results support the notion that a point mutation in the p53 gene impacts skin carcinogenesis quite differently than allelic loss: the former is generally selected for in early stages of skin tumors in wild type mice, whereas the latter enhances tumor development only at high exposure levels (where apoptosis becomes more prevalent) and appears to increase progression (to a higher grade of malignancy) of skin tumors.     

Synthesis and structure-activity relationship of 3-phenyl-3H-quinazolin-4-one derivatives as CXCR3 chemokine receptor antagonists

A series of 3-phenyl-3H-quinazolin-4-ones have been synthesized and tested for affinity and activity at the chemokine CXCR3 receptor. The most potent compound (1d) has been evaluated using radioligand binding and calcium mobilization assays and is considered a useful tool for further characterization of the CXCR3 receptor.