Mother Knows Best: Occurrence and Associations of Resighted Humpback Whales Suggest Maternally Derived Fidelity to a Southern Hemisphere Coastal Feeding Ground

Site fidelity is common among migratory cetaceans, including humpback whales (Megaptera novaeangliae). In the Northern Hemisphere it has been found that fidelity to humpback whale feeding grounds is transferred maternally but this has never been shown for the species in the Southern Hemisphere. We examined this in a unique feeding area off west South Africa using resighting data of 68 individually identified humpback whales by means of photographic (tail flukes and dorsal fins) and/or molecular methods (microsatellite genotyping) over an 18 year span. We found short-term association patterns and recurrent visits typical of other feeding grounds. Males and females had different seasonality of attendance. Significant female-dominated presence corresponded to timing of an expected influx of females on their southward migration from the breeding ground: firstly non-nursing (possibly pregnant) females in mid-spring, and mothers and calves in mid-to late summer. The potential benefit of this mid-latitude feeding area for females is illustrated by a record of a cow with known age of at least 23 years that produced calves in three consecutive years, each of which survived to at least six months of age: the first record of successful post-partum ovulation for this species in the Southern Hemisphere. We recorded association of a weaned calf with its mother, and a recurring association between a non-lactating female and male over more than two years. Moreover, three animals first identified as calves returned to the same area in subsequent years, sometimes on the same day as their mothers. This, together with numerous Parent-Offspring relations detected genetically among and between resighted and non-resighted whales is strongly suggestive of maternally derived site fidelity at a small spatial scale by a small sub-population of humpback whales.     

Stimulus–response characteristics of motor evoked potentials and silent periods in proximal and distal upper-extremity muscles

ObjectiveTo compare stimulus–response characteristics of both motor evoked potentials (MEP) and silent periods (SP) induced by transcranial magnetic stimulation (TMS) in proximal and distal upper-extremity muscles.MethodsStimulus–response curves of MEPs and SPs were obtained from the biceps brachii (BB) and abductor digiti minimi (ADM) muscles in 15 healthy participants. A nonlinear mixed model was used to fit the stimulus–response curves to a sigmoid Boltzmann function.ResultsSmall residuals of the function were found for MEPs and SPs in both muscles. Higher maximal MEP amplitudes were found for the BB compared to the ADM (p < 0.01). The active motor threshold to obtain a SP was less for the ADM compared to the BB (p < 0.01). The slope parameter of the function of the SP duration was steeper and more variable in the ADM than in the BB (p < 0.01). For the MEP amplitude no difference in active motor threshold and slope of the function was found between both muscles.ConclusionsExcitatory (MEP) and inhibitory (SP) effects of TMS differ between proximal arm and distal hand muscles in healthy participants. The adequate fit of our model suggests that this model can be used to study between and within subject changes in future studies.     

Shore‐based observations of seasonality,movements, and group behavior of southern right whales in a nonnursery area on the South African west coast

The southern right whale's (Eubalaena australis) demography, occurrence, habitat use, and behavior off South Africa are known predominantly from an ongoing aerial survey data set that started in 1971. The fixed timeframes of these surveys and their geographical bias towards south coast nursery areas have constrained our knowledge about the right whale's seasonal distribution elsewhere. We present shore‐based observations and tracking of right whales at Saldanha Bay on the west coast (2001–2003) that reveal a near year‐round presence and strongly nearshore distribution. With seasonal progression from winter to summer we observed a gradual increase in sighting rate, reduction in swimming speed, less directionality of movement, an increase in group size, and more surface active groups. The area appears to be important for feeding and socializing but not as a calving or nursery area. Individual transits between the south and west coasts, bidirectional alongshore movements, and extended seasonal presence may all be indicative of reoccupation of their former range along the west coast. This is important given the increasing ship traffic at Saldanha Bay, the rapid expansion of the region's oil and gas industry, and the known vulnerability of the closely related North Atlantic right whale (E. glacialis) to ship strikes.     

Measurement and 3D-Visualization of Cell-Cycle Length Using Double Labelling with Two Thymidine Analogues Applied in Early Heart Development

Organ development is a complex spatial process in which local differences in cell proliferation rate play a key role. Understanding this role requires the measurement of the length of the cell cycle at every position of the three-dimensional (3D) structure. This measurement can be accomplished by exposing the developing embryo to two different thymidine analogues for two different durations immediately followed by tissue fixation. This paper presents a method and a dedicated computer program to measure the resulting labelling indices and subsequently calculate and visualize local cell cycle lengths within the 3D morphological context of a developing organ. By applying this method to the developing heart, we show a large difference in cell cycle lengths between the early heart tube and the adjacent mesenchyme of the pericardial wall. Later in development, a local increase in cell size was found to be associated with a decrease in cell cycle length in the region where the chamber myocardium starts to develop. The combined application of halogenated-thymidine double exposure and image processing enables the automated study of local cell cycle parameters in single specimens in a full 3D context. It can be applied in a wide range of research fields ranging from embryonic development to tissue regeneration and cancer research.     

Horizontal Gene Transfer to Endogenous Endophytic Bacteria from Poplar Improves Phytoremediation of Toluene

Poplar, a plant species frequently used for phytoremediation of groundwater contaminated with organic solvents, was inoculated with the endophyte Burkholderia cepacia VM1468. This strain, whose natural host is yellow lupine, contains the pTOM-Bu61 plasmid coding for constitutively expressed toluene degradation. Noninoculated plants or plants inoculated with the soil bacterium B. cepacia Bu61(pTOM-Bu61) were used as controls. Inoculation of poplar had a positive effect on plant growth in the presence of toluene and reduced the amount of toluene released via evapotranspiration. These effects were more dramatic for VM1468, the endophytic strain, than for Bu61. Remarkably, none of the strains became established at detectable levels in the endophytic community, but there was horizontal gene transfer of pTOM-Bu61 to different members of the endogenous endophytic community, both in the presence and in the absence of toluene. This work is the first report of in planta horizontal gene transfer among plant-associated endophytic bacteria and demonstrates that such transfer could be used to change natural endophytic microbial communities in order to improve the remediation of environmental insults.     

Trafficking of cholinesterases and neuroligins mutant proteins. An association with autism

Autism encompasses a wide spectrum of disorders arising during brain development. Recent studies reported that sequence polymorphisms in neuroligin-3 (NLGN3) and neuroligin-4 (NLGN4) genes have been linked to autism spectrum disorders indicating neuroligin genes as candidate targets in brain disorders. We have characterized a single mutation found in two affected brothers that substituted Arg451 to Cys in NL3. Our data show that the exposed Cys causes retention of the protein in the endoplasmic reticulum (ER) when expressed in HEK-293 cells. To examine whether the introduction of a Cys in the C-terminal region of other alpha/beta-hydrolase fold proteins could promote the same cellular phenotype, we made homologous mutations in acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) and found a similar processing deficiency and intracellular retention (De Jaco et al., J Biol Chem. 2006, 281:9667-76). NL3, AChE and BChE mutant proteins are recognized as misfolded in the ER, and degraded via the proteasome pathway. A 2D electrophoresis coupled with mass spectrometry based approach was used to analyze proteins co-immunoprecipitating with NL3 and show differential expression of factors interacting with wild type and mutant NL3. We identified several proteins belonging to distinct ER resident chaperones families, including calnexin, responsible for playing a role in the folding steps of the AChE and NLs.     

Progress in remediation and revegetation of the barren Jales gold mine spoil after in situ treatments

A series of single extractions and short-term plant tests were performed in order to test a variety of inexpensive mineral amendments for the in situ inactivation of trace elements on the fine-grained spoil of the former gold mine of Jales, Portugal. Based on the results of these tests, mesocosms (lysimeters) were constructed and a small-scale semi-field trial was carried out since 1998. The long-term effect of steelshots (SS, iron grit), beringite (B), and municipal compost (C) as spoil amendments was investigated. Vegetation establishment on the treated spoils was successful with Holcus lanatus L. in year 1 and Pinus pinaster Ait. in year 2. Therefore, a detailed monitoring program was implemented for determining the sustainability of trace elements in situ inactivation by C (5%), CB (5% compost combined with 5% beringite), CSS (5% compost combined with 1% steelshots), and CBSS (5% compost combined with 5% beringite and 1% steelshots) treatments (all amendments are expressed by soil dry weight) and of the revegetation. After 3 years, revegetation was excellent in the CSS treatment, and successful for the CBSS. Volunteer plant species became established in treated spoils during year 2. In contrast, the trees planted on the C treated spoil declined from year 2 and some died. In year 3, the trees on the CB treatment started to decline. Arsenic and zinc exposure are suggested to explain the negative effects on pine growth. In agreement with results of single extractions, compost addition in the spoil increased long-term arsenic percolation. Lead leaching was also enhanced. The CBSS and CSS treatments were the most effective for limiting water-soluble As and decreasing long-term metal leaching.     

Evaluating the impact of DREAMS on HIV incidence among adolescent girls and young women: A population-based cohort study in Kenya and South Africa

BackgroundThrough a multisectoral approach, the DREAMS Partnership aimed to reduce HIV incidence among adolescent girls and young women (AGYW) by 40% over 2 years in high-burden districts across sub-Saharan Africa. DREAMS promotes a combination package of evidence-based interventions to reduce individual, family, partner, and community-based drivers of young women’s heightened HIV risk. We evaluated the impact of DREAMS on HIV incidence among AGYW and young men in 2 settings.Methods and findingsWe directly estimated HIV incidence rates among open population-based cohorts participating in demographic and HIV serological surveys from 2006 to 2018 annually in uMkhanyakude (KwaZulu-Natal, South Africa) and over 6 rounds from 2010 to 2019 in Gem (Siaya, Kenya). We compared HIV incidence among AGYW aged 15 to 24 years before DREAMS and up to 3 years after DREAMS implementation began in 2016. We investigated the timing of any change in HIV incidence and whether the rate of any change accelerated during DREAMS implementation. Comparable analyses were also conducted for young men (20 to 29/34 years).In uMkhanyakude, between 5,000 and 6,000 AGYW were eligible for the serological survey each year, an average of 85% were contacted, and consent rates varied from 37% to 67%. During 26,395 person-years (py), HIV incidence was lower during DREAMS implementation (2016 to 2018) than in the previous 5-year period among 15- to 19-year-old females (4.5 new infections per 100 py as compared with 2.8; age-adjusted rate ratio (aRR) = 0.62, 95% confidence interval [CI] 0.48 to 0.82), and lower among 20- to 24-year-olds (7.1/100 py as compared with 5.8; aRR = 0.82, 95% CI 0.65 to 1.04). Declines preceded DREAMS introduction, beginning from 2012 to 2013 among the younger and 2014 for the older women, with no evidence of more rapid decline during DREAMS implementation. In Gem, between 8,515 and 11,428 AGYW were eligible each survey round, an average of 34% were contacted and offered an HIV test, and consent rates ranged from 84% to 99%. During 10,382 py, declines in HIV incidence among 15- to 19-year-olds began before DREAMS and did not change after DREAMS introduction. Among 20- to 24-year-olds in Gem, HIV incidence estimates were lower during DREAMS implementation (0.64/100 py) compared with the pre-DREAMS period (0.94/100 py), with no statistical evidence of a decline (aRR = 0.69, 95% CI 0.53 to 2.18). Among young men, declines in HIV incidence were greater than those observed among AGYW and also began prior to DREAMS investments. Study limitations include low study power in Kenya and the introduction of other interventions such as universal treatment for HIV during the study period.ConclusionsSubstantial declines in HIV incidence among AGYW were observed, but most began before DREAMS introduction and did not accelerate in the first 3 years of DREAMS implementation. Like the declines observed among young men, they are likely driven by earlier and ongoing investments in HIV testing and treatment. Longer-term implementation and evaluation are needed to assess the impact of such a complex HIV prevention intervention and to help accelerate reductions in HIV incidence among young women.

Isolde Birdthistle and co-workers evaluate a program to address risks of HIV infection in adolescent girls and young women in sub-Saharan Africa.