A rare case of de novo distal 19q trisomy prenatally diagnosed

We present a case of de novo trisomy of distal 19q diagnosed prenatally by cytogenetics and FISH analysis. The autopsy performed after termination of the pregnancy showed major internal and external malformations that are associated with this chromosome abnormality. Copyright © 2004 John Wiley & Sons, Ltd.     

Ivemark syndrome with agenesis of the corpus callosum: a case report with a review of the literature

Asplenia associated with situs ambiguus, symmetric liver, bilateral trilobulated lungs, and a complex heart defect was diagnosed on autopsy in a 14-day-old infant. Furthermore, examination of the brain displayed agenesis of the corpus callosum (ACC) with pachygyria and hydrocephalus. The characteristic association of asplenia with visceroatrial heterotaxia is traditionally named after the Swedish pediatrician, Ivemark. Although exceptional, association of Ivemark syndrome with callosal agenesis has been reported recently. The concept of ‘developmental fields’ describes morphogenetically reactive units of the embryo determining and controlling the development of complex structures in a hierarchical manner. Lateralization defects such as situs inversus, asplenia or polysplenia due to defective left–right axis development, as well as decussation defects such as ACC, are considered as defects of the primary developmental field. Therefore, additional callosal agenesis in Ivemark syndrome may be a coherent and synchronic defect in the primary developmental field rather than a causally independent malformation. Copyright © 2002 John Wiley & Sons, Ltd.     

Forest dynamics after successive spruce budworm outbreaks in mixedwood forests

In order to assess the long-term spatiotemporal influence of the spruce budworm in sub-boreal mixedwood forests, we studied the effect of three successive outbreaks in a region of western Quebec, Canada. We used dendrochronology to detect past outbreaks in three areas (111-185 ha), based on the recruitment age of balsam fir (Abies balsamea) and on growth patterns of white spruce (Picea glauca), the two main host species of this defoliating insect. We also used a series of aerial photographs taken between 1935 and 2003 to evaluate overstory mortality and post-outbreak succession patterns in these same areas. Individual outbreaks had a spatially homogenous impact on host species throughout the region, but successive outbreaks differed in intensity: the two outbreaks around 1910 and 1980 caused widespread mortality in the overstory, but an outbreak around 1945 had little impact, probably because the forest mosaic had not yet recuperated from the 1910 outbreak. No clear outbreak was detected in the later part of the 19th century. In portions of the study areas where the 1910 outbreak had a major impact, between 36% and 50% of the stands were reoccupied by balsam fir stands in the period up to the 1980 outbreak (cyclic succession), the rest being at least partly replaced by nonhost species such as Betula spp. Changes in forest composition after the 1910 outbreak were mostly associated with upper-slope positions in all study areas. The 1980 outbreak also had a higher impact than earlier outbreaks in lower-slope positions dominated by black spruce (Picea mariana)-balsam fir mixtures. These results suggest that, at the regional scale, the abundance of mature or over-mature balsam fir stands does not determine the outbreak cycle. When an outbreak occurs, however, its impact will be strongly constrained by forest characteristics such as stand composition and structure, which are themselves influenced by previous disturbances and slope position.     

Assessment of ecotoxicological risks related to depositing dredged materials from canals in northern France on soil

The implementation of an ecological risk assessment framework is presented for dredged material deposits on soil close to a canal and groundwater, and tested with sediment samples from canals in northern France. This framework includes two steps: a simplified risk assessment based on contaminant concentrations and a detailed risk assessment based on toxicity bioassays and column leaching tests. The tested framework includes three related assumptions: (a) effects on plants (Lolium perenne L.), (b) effects on aquatic organisms (Escherichia coli, Pseudokirchneriella subcapitata, Ceriodaphnia dubia, and Xenopus laevis) and (c) effects on groundwater contamination. Several exposure conditions were tested using standardised bioassays. According to the specific dredged material tested, the three assumptions were more or less discriminatory, soil and groundwater pollution being the most sensitive. Several aspects of the assessment procedure must now be improved, in particular assessment endpoint design for risks to ecosystems (e.g., integration of pollutant bioaccumulation), bioassay protocols and column leaching test design.     

Operational leeway in work situations: do ergonomic risk assessment tools consider operational leeway for job analysis?

Our study shows that information on operational leeway is limited in the originator articles of the ergonomic risk assessment tools for prevention of musculoskeletal disorders (MSDs). The tools’ underlying theoretical models do not consider the indicators of operational leeway, and they cannot determine the sufficiency of the situational operational leeway in a work situation. Consequently, regulation of the activity, which ensures the performance goals and the individual's health, has been overlooked. The lack of literature on indicators of situational operational leeway is one of the reasons for this deficit. Defining the indicators for this concept would be an innovation in the approach of MSD risk prevention. Developing empirically the concept of situational operational leeway in risk assessment tools would help to progress the current approach of MSD prevention. This study therefore proposes indicators of situational operational leeway to increase the representativeness and reliability of the risk assessment tools for MSDs.     

Replacement of reproductives in Nasutitermes princeps (Desneux) (Isoptera: Termitidae)

Summary The production of replacement reproductives in experimentally orphaned societies was investigated in Nasutitermes princeps (Desneux). From 1 to 180 replacement queens and multiple kings, all adultoids, were found in the 13 nests that were re-collected. Normal imagos, microimagos, or a mixture of the two forms were present, depending on colony composition at the time of orphaning. In colonies with alates, the corresponding forms were found as replacement reproductives. Where only young nymphs were present, microimagos differentiated. Neither the number of queens nor their level of physogastry was correlated with the time elapsed since orphaning, but the total egg-laying rates were. We suggest that competition among queens rather than time determines individual physogastric development. Observations show that the most likely cause of accidental queen death in nature is probably nest fall from the supporting tree. Even in this case, the queen may be able to migrate to a newly rebuilt nest. An experimental simulation of this situation showed that colony migration can occur. The data indicate that the replacement of the primary queen after her accidental death cannot by itself account for the high rate of polygyny (60%) encountered in N. princeps. Two other possible causes are the replacement of the ageing foundress as a normal event of colony life, and colony reproduction by budding off new nests with adultoid reproductives.King Léopold III Biological Station, Laing Island, Papua New Guinea, contribution no. 84Research Assistant of the National Fund for Scientific Research (Belgium)     

加拿大北方森林过去、当前和未来的火灾频率:对于森林可持续经营的意义

在过去的几十年里,对基于对历史上自然干预动力的理解的森林经营方法的开发兴趣日益增加.这一方法的理由是,有利于景观组成和林分结构及自然生态系统的经营活动也应当保持生物多样性和基本的生态功能.在火灾居支配地位的景观,用森林经营替代火灾这一方法只在当前火频率和未来火频率比工业化以前的火频率低得多的情况下才有可能.通过将当前火频率、未来火频率与在加拿大北方森林中再现的森林火灾历史的比较,我们讨论了这一问题.对于多块研究地而言,当前火频率和2倍CO.及3倍CO2情形下模拟的未来火频率都低于过去火频率,这暗示着森林经营可以被用于重建受控于火灾的、工业化以前景观的林木年龄结构.但对目前的同龄林经营来说,还有一些重要的限制因子.