Unscheduled apoptosis in meristematic plant cells is triggered via terminal deletions in artificially elongated chromosome arms

 Chromosomes elongated beyond a critical size by balanced rearrangements reduce the viability and fertility of field bean individuals. The severity of symptoms, ranging from growth retardation to early death of seedlings, increases with the length of the longest chromosome arm. This is paralleled by the incomplete separation of sister chromatids during nuclear division, resulting in chromatin connections between daughter nuclei which become disrupted by cell-wall formation and yield chromatid deletions detectable as micronuclei. By means of the TUNEL assay we show that, compared to the wild-type, a >6-fold higher number of meristematic cells of karyotypes with chromosome arms surpassing the limit of tolerance reveal apoptotic nuclei and are prone to die. Thus, terminal chromatid deletions apparently trigger unscheduled apoptosis. Extensive cell death in meristems is eventually responsible for reduced growth, disturbed development and reduced seed set. Differentiated root tissues and microspores did not reveal apoptotic nuclei. Received: 20 November 1997 / Accepted: 9 December 1997     

Habitat fragmentation and plant populations: is what we know demographically irrelevant?

Abstract: Habitat fragmentation is considered a leading cause of plant extinction, and matrix models provide a powerful set of tools with which to identifying mechanisms that influence population declines. We surveyed the ecological literature to determine what components of plant demography have been studied in fragmented habitats, and determined the elasticity values of the vital rates influenced by these components. We found that there is a major disparity between the ecological processes and stages of life history with large demographic impacts and the focus of empirical research on plants in fragmented habitats. While the growth and survivorship of large, established individuals have the highest elasticity values, the focus of empirical research has been on components of reproduction and seedling dynamics. We argue that elucidating the demographic mechanisms underlying population declines in fragmented habitats, and developing strategies for mitigating these declines, will be challenging without a greater focus on understanding how fragmentation alters adult plant growth and survivorship.     

女性受教育程度与其生育水平关系的数学模型分析

本文对我国女性受教育程度与其活产子女数、总和孩次递比等重要的生育水平指标间的关系进行了全面而深入的统计分析，并得到反映其定量关系的回归方程数学模型，从而揭示出女性受教育程度对其生育水平所具有的重大作用。     

Evolutionary sex allocation theory explains sex ratios in natural Plasmodium falciparum infections

Malaria transmission is achieved by sexual stages, called gametocytes, and the proportion of gametocytes that are male versus female (sex ratio) influences transmission success. In malaria model systems, variation in gametocyte sex ratios can be explained by the predictions of evolutionary sex allocation theory. We test these predictions using natural Plasmodium falciparum infections. The predicted negative correlation between sex ratio and gametocyte density holds: the sex ratio increases when gametocyte densities decrease, and this is most apparent in single genotype infections and in the dry season. We do not observe higher gametocyte sex ratios in mixed compared with single genotype infections.     

The relationship between a nuclear restorer gene and the nuclear gene for male sterility in Petunia

Summary This paper describes the relationship between the restorer gene and the gene for male sterility in the background of normal cytoplasm. We combined these two traits by crosses in one plant, thus making genetic analysis possible. Two main conclusions can be drawn: 1. The restorer gene and the gene for male sterility are located at different loci which segregate independently one from the other. 2. The Rf allele does not affect the expression of the e allele.Contribution from the Department of Plant Genetics and Breeding, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. 1983 series, No. 779 E     

Lycopene is superior to moringa in improving fertility markers in diet-induced obesity male rats

Obesity is a condition of chronic tissue inflammation and oxidative stress that poses as a risk factor for male infertility. Moringa oleifera oil extract is known to have cholesterol-lowering properties and a potential to treat obesity, while lycopene is a potent antioxidant. We hypothesize that Moringa or lycopene may improve male fertility markers in an animal model of diet-induced obesity. Male Albino rats (n = 60) were randomized to receive regular chow (RC) or high-fat diet (HFD) for 12 weeks (n = 30 each). Animals in each arm were further randomized to receive gavage treatment with corn oil (vehicle), lycopene (10 mg/kg), or Moringa (400 mg/kg) for four weeks starting on week 9 (n = 10 each). Animals were sacrificed at 12 weeks, and blood was collected to assess lipid profile, serum testosterone, and gonadotropin levels. The testes and epididymides were removed for sperm analysis, oxidative stress and inflammatory markers, and histopathological assessment. In comparison to their RC littermates, animals on HFD showed an increase in body weights, serum lipids, testosterone and gonadotrophin levels, testicular oxidative stress and inflammatory markers, as well as sperm abnormalities and disrupted testicular histology. Moringa or lycopene reduced body weight, improved oxidative stress, and male fertility markers in HFD-fed animals with lycopene exhibiting better anti-antioxidant and anti-lipidemic effects. Lycopene is superior to Moringa in improving male fertility parameters, possibly by attenuating oxidative stress.     

The impact of lockdowns during the COVID-19 pandemic on fertility intentions

Lockdown edicts during the COVID-19 pandemic have led to concerns about consequences for childbirth plans and decisions. Robust empirical research to either refute or confirm these concerns, however, is lacking. To evaluate the causal impact of lockdowns on fertility, we exploited a large sample of Australians (aged 18–45) from a nationally representative household panel survey and leveraged variation from a unique natural experiment that occurred in Australia in 2020: a lockdown imposed in the state of Victoria, but not elsewhere in Australia. Difference-in-differences models were estimated comparing changes in fertility intentions of persons who resided in Victoria during lockdown, or within four weeks of the lockdown being lifted, and those living elsewhere in Australia. Results revealed a significantly larger decline in reported intentions of having another child among women who lived through the protracted lockdown. The average effect was small, with fertility intentions estimated to fall by between 2.8% and 4.3% of the pre-pandemic mean. This negative effect was, however, more pronounced among those aged over 35 years, the less educated, and those employed on fixed-term contracts. Impacts on men’s fertility intentions were generally negligible, but with a notable exception being Indigenous Australians.     

Taxonomical status and phylogenetic relations between the “thomasi” and “atticus” chromosomal races of the underground vole Microtus thomasi (Rodentia, Arvicolinae)

Laboratory crosses among wild caught individuals of the chromosomal races “atticus” and “thomasi”, were performed to analyze the degree of interracial reproductive isolation. The fertility of the studied specimens was evaluated by taking into consideration the reproductive success, the litter size and performing comparative histological examination of the testicular material. All studied populations were submitted to classical cytogenetic and mitochondrial analysis (cytochrome b gene), providing new evidences to the potential phylogenetic relations and taxonomical status of the two chromosomal races. The previously described “atticus” populations are divided in two genetically distinct, geographically and reproductively isolated lineages (2.9% total and 2.4% net divergence), which probably derived from different glacial refugia of Southern Greece. Here, we suggest that the lineage, consisting of the populations from Attiki and Evia Island, should be distinguished as a valid species, named Microtus atticus, including the two chromosomal races “atticus” and “evia”. On the contrary, the ex-“atticus” populations from North Peloponnesus belong to the same mitochondrial lineage with the other Microtus thomasi populations and should be considered as a chromosomal polymorphism inside the chromosomal race “thomasi”.     

The relationship between sperm quality in cool-shipped semen and embryo recovery rate in horses

The relationship between the quality of cool-shipped stallion semen and fertility has not been adequately described. This study evaluated sperm quality of cool-shipped semen from 459 ejaculates (N = 130 stallions) that were used for insemination of 196 embryo donor mares (n = 496 estrous cycles). Embryo recovery rate (ERR; %) increased, as all sperm measures (e.g., motility, viability, DNA quality, morphology, concentration, and total number) increased. Threshold values are reported for each sperm quality measure (e.g., total sperm motility ≥ 65%) that separate two ERR groups (e.g., average: ∼50% ERR; high: ∼65% ERR).