Sharing of photobionts in sympatric populations of Thamnolia and Cetraria lichens: evidence from high-throughput sequencing.

In this study, we explored the diversity of green algal symbionts (photobionts) in sympatric populations of the cosmopolitan lichen-forming fungi Thamnolia and Cetraria. We sequenced with both Sanger and Ion Torrent High-Throughput Sequencing technologies the photobiont ITS-region of 30 lichen thalli from two islands: Iceland and Öland. While Sanger recovered just one photobiont genotype from each thallus, the Ion Torrent data recovered 10-18 OTUs for each pool of 5 lichen thalli, suggesting that individual lichens can contain heterogeneous photobiont populations. Both methods showed evidence for photobiont sharing between Thamnolia and Cetraria on Iceland. In contrast, our data suggest that on Öland the two mycobionts associate with distinct photobiont communities, with few shared OTUs revealed by Ion Torrent sequencing. Furthermore, by comparing our sequences with public data, we identified closely related photobionts from geographically distant localities. Taken together, we suggest that the photobiont composition in Thamnolia and Cetraria results from both photobiont-mycobiont codispersal and local acquisition during mycobiont establishment and/or lichen growth. We hypothesize that this is a successful strategy for lichens to be flexible in the use of the most adapted photobiont for the environment.

The spatial structure of bacterial communities is influenced by historical environmental conditions.

The spatial structure of ecological communities, including that of bacteria, is often influenced by species sorting by contemporary environmental conditions. Moreover, historical processes, i.e., ecological and evolutionary events that have occurred at some point in the past, such as dispersal limitation, drift, priority effects, or selection by past environmental conditions, can be important, but are generally investigated much less. Here, we conducted a field study using 16 rock pools, where we specifically compared the importance of past vs. contemporary environmental conditions for bacterial community structure by correlating present differences in bacterial community composition among pools to environmental conditions measured on the same day, as well as to those measured 2, 4, 6, and 8 d earlier. The results prove that selection by past environmental conditions exists, since we were able to show that bacterial communities are, to a greater extent, an imprint of past compared to contemporary environmental conditions. We suggest that this is the result of a combination of different mechanisms, including priority effects that cause rapid adaptation to new environmental conditions of taxa that have been initially selected by past environmental conditions, and slower rates of turnover in community composition compared to environmental conditions.

Acute fetal asphyxia and permanent brain injury: a retrospective analysis of current indicators.

OBJECTIVE: To determine whether a term neonate who has had sufficient intrapartum asphyxia to produce persistent brain injury will manifest the following four criteria: profound acidemia (arterial pH <7.00), an APGAR score < or =3 for 5 min or longer, seizures within 24 h of birth, and multiorgan system dysfunction. METHODS: Singleton, liveborn, neurologically impaired neonates > or =37 weeks gestation who lived at least 6 days and had sufficient documentation of current intrapartum asphyxia criteria were retrospectively analyzed. Of these infants, solely neonates with acute fetal asphyxia due to a sudden prolonged FHR deceleration that lasted until delivery from a catastrophic event, e.g., uterine rupture, cord prolapse, were included. Organ system dysfunction was defined by separate criteria for each organ system. Dysfunction in one or more was defined as multiorgan system dysfunction. RESULTS: Of the 292 eligible infants in the registry, 47 satisfied the entry criteria. In these 47 neonates, 10 (21%) satisfied all 4 criteria for intrapartum asphyxia. CONCLUSIONS: Our retrospective study suggests that currently used indicators to define permanent fetal brain injury are not valid.

DNA content and differentiation of root apical cells of Brassica rapa plants grown in microgravity.

Root cap is proposed to be a graviperceptive tissue in the plant root, and it is composed of several cell types. One such cell type, the columella cells, are thought to initiate the gravity-induced signal transduction cascade, and these cells arise from the activity of the meristematic zone of the root cap. There is, in fact, a continuum of cells in the central column of the root cap representing the meristematic cells, developing columella cells, mature cells, and those that will soon be sloughed off into the soil. In order to study the functional roles of the root cap cells in gravity-sensing, we compared the ultrastructural organization, differentiation, and DNA content in the meristematic, elongating, and differentiating cells of root tips in Brassica rapa plants grown in space microgravity and at 1g. The experiments were also designed to determine the reactions of root cap cells in both main roots (in which the original root cap was present in an embryonic form within the seed) and lateral roots (in which the root cap formed completely in space after seed germination on orbit) to the space microgravity. This study (ROOTS) was performed in collaboration with the B-PAC experiment on the Space shuttle "Columbia" mission STS-87 (Collaborative US/Ukrainian Experiment (CUE) during November 19-December 5, 1997.

Does the onset of neonatal seizures correlate with the timing of fetal neurologic injury?

The onset of seizures after birth has been considered evidence of an intrapartum asphyxial event. The present study was undertaken to determine whether the timing of neonatal seizures after birth correlated with the timing of a fetal asphyxial event. Thus, singleton term infants diagnosed with hypoxic ischemic encephalopathy and permanent brain injury had a mean birth to seizure onset interval of 9.8 +/- 17.7 (range 1-90) hours. When these infants were categorized according to their fetal heart rate (FHR) patterns, the acute group (normal FHR followed by a sudden prolonged FHR deceleration that continued until delivery) tended to have earlier seizures than infants did within the tachycardia group (normal FHR followed by tachycardia, repetitive decelerations, and diminished variability) and the preadmission group (persistent nonreactive FHR pattern intrapartum). These seizure intervals were as follows: acute, 6.6 +/- 18.0 (range 1-90) hours; tachycardia, 11.1 +/- 17.1 (range 1-61) hours; and preadmission, 11.8 +/- 17.9 (range 1-79) hours (p < 0.05). But the range varied widely and no group was categorically distinct. In conclusion, the onset of neonatal seizures after birth does not, in and of itself, appear to be a reliable indicator of the timing of fetal neurologic injury.

Future financial neonatal shock.

In a changing economic climate, the neonatologist must be aware of all of the forces that can affect the practice of neonatology. In addition to clinical issues, billing and reimbursement must take into account physician work and common procedural terminology (CPT) codes, which accurately describe the medical services and procedures delivered. An understanding of this coding and resource-based work unit system is necessary to prevent financial loss. The influence of managed care, capitation, fixed per-case reimbursement, practice guidelines and care maps have already seriously affected clinical practice patterns. The neonatologist must be proactive in negotiating contracts using historic information and outcome data to define and defend the quality of care provided.

Neonatal nucleated red blood cell and lymphocyte counts in fetal brain injury.

OBJECTIVE: To determine whether neonatal lymphocyte or nucleated red blood cell (RBC) counts can be used to date fetal neurologic injury. METHODS: Singleton, term infants with hypoxic-ischemic encephalopathy, permanent neurologic impairment, and sufficient laboratory data were divided into two groups: infants with preadmission injury, manifested by a nonreactive fetal heart rate (FHR) pattern from admission until delivery; and infants with acute injury, manifested by a normal FHR pattern followed by a sudden prolonged FHR deceleration. Lymphocyte and nucleated RBC values were compared with published high normal counts for normal neonates: 8000 lymphocytes/mm3 and 2000 nucleated RBCs/mm3. RESULTS: The study population consisted of 101 neonates. In the first hours of life, lymphocyte counts were elevated among injured newborns, and then the counts rapidly normalized. Brain-injured neonates were 25 times more likely to have a lymphocyte count greater than 8000 than were normal neonates (54 [62%] of 87 versus 6 [7%] of 84; odds ratio 25.5; 95% confidence interval 8.8, 80.1; P < .001). The mean lymphocyte count tended to be higher in the preadmission-injury group than in the acute-injury group. In comparison, nucleated RBC values were not correlated as strongly with neonatal hours of life; nucleated RBC counts tended to be higher and persist longer among neonates with preadmission injury than among those with acute injury. CONCLUSION: Compared with normal levels, both lymphocyte and nucleated RBC counts were elevated among neonates with fetal asphyxial injury. Both counts appear to be more elevated and to remain elevated longer in newborns with preadmission injury than in infants with acute injury. However, the rapid normalization of lymphocyte counts in these injured neonates limits the clinical usefulness of these counts after the first several hours of life.

Intrapartum fetal asphyxial brain injury with absent multiorgan system dysfunction.

Current understanding of the physiologic mechanisms of intrapartum fetal asphyxial brain injury has suggested a strong association with multiorgan system injury. Thus the purpose here is to describe 14 cases of severe fetal brain injury with absent multiorgan system dysfunction (MSD). The study population was drawn from a national registry for brain injured infants. MSD was defined by clinical criteria demonstrated to reflect asphyxial injury to the pulmonary, renal, cardiac, hematologic, hepatic, and gastrointestinal systems. Involvement of one other organ in addition to the brain was defined as multiorgan system dysfunction. All infants were diagnosed with hypoxic-ischemic encephalopathy (HIE) in the neonatal period and went on to have permanent central nervous system (CNS) injury and MSD criteria were not met. Of the 292 term, singleton infants with HIE and permanent neurologic injury, 57 (20%) satisfied the entry criteria; of these, 14 (36%) had no MSD. The underlying basis for the fetal brain injury were: uterine rupture, 6 (43%), prolonged FHR deceleration, 5 (36%), fetal exsanguination, 1 (7%), cord prolapse, 1 (7%), and maternal cardiopulmonary arrest, 1 (7%). The mean duration of the prolonged FHR deceleration was 32.1 +/- 9.1 (range 19-51) minutes. All infants were later diagnosed with cerebral palsy. Intrapartum fetal asphyxial brain injury may not necessarily proceed through a physiologic mechanism in which the fetal circulation is centralized and endorgans damaged. These acute injuries, associated with a prolonged FHR deceleration, may be linked to severely decreased cardiac output and hypotension that cause vulnerable portions of the brain to be injured before other organs.