Scent Marking in Voles: A Reassessment of Over Marking, Counter Marking, and Self-Advertisement

We conducted a series of experiments to discern among the counter-marking, over-marking, and self-advertisement hypotheses for secondary marking in male prairie voles, Microtus ochrogaster , and meadow voles, M. pennsylvanicus . Secondary scent marks (those placed in an area that has already been marked by a conspecific) were not significantly greater than initial marks placed on clean substrate (a substrate without any previous scent marks) for either species and thus did not support a counter-marking hypothesis. Similarly, overlapping of initial scent marks with secondary marks occurred less often than expected by chance and did not support an over-marking hypothesis. Secondary marks tended to avoid overlap with scent marks previously deposited by a potential competitor. Our results suggest that secondary scent marking functions to self-advertise by maximizing individual identity and avoiding masking or blending with previous donors. Future studies on secondary marking should be designed to quantify the observed and expected frequency and placement of original and secondary marks to discern among alternative hypotheses for the adaptive significance of secondary marking.     

Radioactive Marking of Small Mammals

The literature on the use of radioactive materials in various kinds of ecological work on small mammals is reviewed under three main headings–inert implants used as markers for tracing movements, external radioactive tags used for similar purposes, and metabolizable radionuclides introduced into the animals' bodies not only for direct tracing of movements of the marked individuals, but for indirect tracing by detecting radioactive excreta, and by automatic marking of offspring and ectoparasites, which can in turn be identified and traced. A comprehensive table summarizes the literature reviewed, and summarizes also the characteristics of the various radioactive isotopes used or suggested for use.
Tests were carried out on various possible methods of using iodine-131 as a marker for small mammals. Intraperitoneal injection of 131-iodide as silver iodide or bound to an ion-exchange resin gave an unsatisfactorily short biological half-life for direct tracing but might be useful for detecting excreta. Silver 131-iodide incorporated in epoxy resin and encapsulated in metal or plastic could prove to be a useful implant.
Silver 131 -iodide paint was quickly removed from the animals' fur by grooming, but might be useful for insects.
Silver-131-iodide–Araldite mixture on a leg ring proved useful, despite the inherent disadvantages of leg rings.     

Marking cell lineages in living tissues

We have generated a novel genetic system to visualize cell lineages in living tissues at high resolution. Heat shock was used to trigger the excision of a specific transposon and activation of a fluorescent marker gene. A histone-YFP marker was used to allow identification of cell lineages and easy counting of cells. Constitutive expression of a green fluorescent membrane protein was used to provide a precise outline of all surrounding cells. Marked lineages can be induced from specific cells within the organism by targeted laser irradiation, and the fate of the marked cells can be followed non-invasively. We have used the system to map cell lineages originating from the initials of primary and lateral roots in Arabidopsis. The lineage marking technique enabled us to measure the differential contribution of primary root pericycle cell files to developing lateral root primordia. The majority of cells in an emerging lateral root primordium derive from the central file of pericycle founder cells while off-centre founder cells contribute only a minor proliferation of tissue near the base of the root. The system shows great promise for the detailed study of cell division during morphogenesis.     

The Setting and Marking of Microbiology Examinations

A rapid, simple method for testing and improving a student's ability to detect and correct misuse of scientific English is described. Performance in such Precision Tests was positively correlated with performance in conventional examinations, and use of these tests in the manner described was followed by an improvement in examination performance. The data discussed in this paper concern the use of Precision Tests in the teaching of biochemistry, but the tests may also prove useful in other biological disciplines.     

标记减数分裂遗传重组的免疫荧光染色方法

联会复合体免疫荧光技术在全基因减数分裂遗传重组研究中具有精确和直观的优势.本研究通过免疫荧光染色方法制备小鼠精母细胞联会复合体,研究其形态组成与遗传重组特征,展示雄性小鼠遗传重组图谱并分析其重组位点(MLH1位点)的分布特征.4只小鼠共145个精母细胞在平均每个细胞的MLH1位点数为23.3±2.4;在常染色体联会复合体中,未发现有3个MLH1位点的联会复合体,具有1个MLH1位点的联会复合体较多,平均为14.2;无XY联会复合体的细胞占所有细胞的4.1%,XY联会复合体上有MLH1位点的细胞占30.2%;联会复合体上有裂缝的细胞占0.7%.通过联会复合体免疫荧光染色可以清晰地分辨出联会复合体(红色)、着丝粒(蓝色)和MLH1位点(绿色),是遗传重组分析的一种强有力工具.     

Affectedness and Differential Object Marking in Spanish

In this study we investigate the impact of affectedness on the diachronic development of Differential Object Marking (DOM) in Spanish. DOM in Spanish synchronically depends on (i) the referential features of the direct object, such as animacy and referentiality, and (ii) the semantics of the verb. Several studies have also shown that the diachronic development of DOM proceeds along the Animacy Scale and the Referentiality Scale, and some recent corpus studies have indicated an influence of the verb??s semantics on this diachronic process. This study presents new findings from a detailed analysis of extensive corpus research on the distribution of DOM with respect to affectedness, understood as ??the persistent change of an event participant??. We use Tsunoda??s Affectedness Scale to order the verb classes under investigation. Our findings provide evidence that this scale can be partly correlated with the diachronic spread of DOM in Spanish which would tend to confirm the influence of verbal semantics on DOM in Spanish.     

探索标记镇海棘螈的方法

研究小组在教师指导下,积极探索标记镇海棘螈的方法,形成了若干方案,并对每个方案的操作方法和优缺点进行论述。     

Marking live conifer pollen for long-distance dispersal experiments

Long-distance dispersal (LDD) theory requires a method for marking live LDD pollen. Such a method must complement more intensive sampling methods inclusive of molecular cytogenetics, proteomics and genomics. We developed a new method for marking live Pinus taeda pollen using two dyes, rhodamine 123 and aniline blue, dissolved in a sucrose solution. Marked and unmarked pollen were compared with respect to in vitro germination, storage, terminal velocity, and in vivo pollen tube penetration of ovules. We found that: (1) both types of marked pollen retained their capacity for germination, (2) both types of marked pollen had similar aerodynamic properties when compared to unmarked pollen controls, (3) marked pollen retained its germination capacity for 48 h, and (4) of the marked pollen, only the aniline-marked pollen penetrated ovules during pollination. Germination declined rapidly for both types of marked pollen after 48 h and before 37 days at -20°C storage, while unmarked pollen lots retained 93% germination at all stages. This method for marking live P. taeda pollen is feasible for tracing LDD pollen only if released and deposited within 48 h of dye treatment.     

Lucifer Yellow, Neuronal Marking and Paraffin Sectioning

An unusual procedure with the dye lucifer yellow has provided stable neuronal marking that survives paraffin embedding and sectioning. Lucifer yellow CH was dissolved in an electrolyte containing formaldehyde and injected into the large intemeurons of a cricket. Intense fluorescence in the axoplasm was retained even after conventional histological procedures.