We documented the pattern of cell development in Euplotes charon. The ontogenesis of this species was similar to many of its congeners, except for the formation of the caudal cirri. In E. Charon, a caudal cirrus is fo...We documented the pattern of cell development in Euplotes charon. The ontogenesis of this species was similar to many of its congeners, except for the formation of the caudal cirri. In E. Charon, a caudal cirrus is formed posterior to each of the rightmost two or three dorsal kinety anlage in the proter, and the second rightmost dorsal kinety in the opisthe. In addition, two caudal cirri are formed posterior to the rightmost dorsal kinety in the opisthe. This pattern of development represents a completely new type. Based on our evaluation, and in comparison with previous studies, we also conclude that the pattern of cell development is variable among species in the Euplotes genera. The variation is particularly evident during the formation of frontoventral and caudal cirri. Based on the segmentation pattern of frontal-midventral transverse cirral anlagen, cirri reduction, and migration of frontoventral cirri, we identified five types: the affinis-type, the eurystomus-type, the charon-type, the raikovi-type and orientalis-type. Euplotes (s. l.) can also be divided into three types based on the formation of caudal cirri: focardii-type, vannus-type and charon-type. Indeed, we conclude that the number (one or two) of marginal cirri should be given as much consideration as the genetic separation. Given this, we reassessed the validity of using genetic separation to classify the group. Generally, the morphogenetic data disagreed with the molecular data (SSrRNA gene sequences). Given these discrepancies, it is too early to draw conclusions on the systematic arrangement of this species-rich taxon.展开更多
Measurements of concentrations of easily extractable soil nitrogen(N) were carried out on samples collected at the Heron Wood Reserve,Scotland,concurrently with investigations of N associated with total microbial biom...Measurements of concentrations of easily extractable soil nitrogen(N) were carried out on samples collected at the Heron Wood Reserve,Scotland,concurrently with investigations of N associated with total microbial biomass and the abundances of bacteria,fungi,and invertebrates.Soil biota at the studied site appeared to be limited by N.There was a remarkable difference between the ambient(i.e.,easily extractable N) and biomass nitrogen.The abundance data of bacteria,protozoa and nematodes significantly negatively correlated with ambient N but showed positive correlations with the total microbial N content.There were,however,remarkable differences between the correlation patterns exhibited by the fungal and the bacterial pathways,as fungi did not show any correlations with chemical variables.These differences should be taken into account whilst interpreting biological interactions both at this important site and elsewhere.展开更多
基金Supported by the Natural Science Foundation of China (No. 40906065)the China Postdoctoral Science Foundation (No. 20090451351)a grant from the Center of Excellence in Biodiversity, King Saud University
文摘We documented the pattern of cell development in Euplotes charon. The ontogenesis of this species was similar to many of its congeners, except for the formation of the caudal cirri. In E. Charon, a caudal cirrus is formed posterior to each of the rightmost two or three dorsal kinety anlage in the proter, and the second rightmost dorsal kinety in the opisthe. In addition, two caudal cirri are formed posterior to the rightmost dorsal kinety in the opisthe. This pattern of development represents a completely new type. Based on our evaluation, and in comparison with previous studies, we also conclude that the pattern of cell development is variable among species in the Euplotes genera. The variation is particularly evident during the formation of frontoventral and caudal cirri. Based on the segmentation pattern of frontal-midventral transverse cirral anlagen, cirri reduction, and migration of frontoventral cirri, we identified five types: the affinis-type, the eurystomus-type, the charon-type, the raikovi-type and orientalis-type. Euplotes (s. l.) can also be divided into three types based on the formation of caudal cirri: focardii-type, vannus-type and charon-type. Indeed, we conclude that the number (one or two) of marginal cirri should be given as much consideration as the genetic separation. Given this, we reassessed the validity of using genetic separation to classify the group. Generally, the morphogenetic data disagreed with the molecular data (SSrRNA gene sequences). Given these discrepancies, it is too early to draw conclusions on the systematic arrangement of this species-rich taxon.
基金Supported by the Scottish Higher Education Funding Council (SHEFC),UKthe European Social Fund (ESF),UK.
文摘Measurements of concentrations of easily extractable soil nitrogen(N) were carried out on samples collected at the Heron Wood Reserve,Scotland,concurrently with investigations of N associated with total microbial biomass and the abundances of bacteria,fungi,and invertebrates.Soil biota at the studied site appeared to be limited by N.There was a remarkable difference between the ambient(i.e.,easily extractable N) and biomass nitrogen.The abundance data of bacteria,protozoa and nematodes significantly negatively correlated with ambient N but showed positive correlations with the total microbial N content.There were,however,remarkable differences between the correlation patterns exhibited by the fungal and the bacterial pathways,as fungi did not show any correlations with chemical variables.These differences should be taken into account whilst interpreting biological interactions both at this important site and elsewhere.
