Sal

In trying to isolate Trebouxia from an Evernia lichen. I found that some of the cultures are contaminated by a what I think are rotifers. I am not sure of what kind of rotifer (or other organism) is the one pictured, so if anyone has some idea please let me know.

I also recorded a video of what I think are belloid rotifers feeding on the same lichen culture:

https://peertube.uno/w/uoSCNagVVmbuMcgXdVfPGR

I don't have much hope that the algae will survive this attack, but I might turn those jars into rotifer cultures.

I left a slide with some algae and rotifers sitting on the microscope. After it dried up I was able to see several of these flower-like shapes. Not a pattern that I had seen before, and I a don't know what about the drying process lead to this particular shapes forming.

I encountered this golden young pigeon today

About two years ago I wanted to learn more about lichen. Since I cultivate mushrooms as hobby, I figured that attempting to isolate the wild lichen symbionts and then re-synthesizing the lichen would be a good way to learn about them. The experiment was not successful, in part because it is a long process and at one stage I did not give it the attention it needed. But at least I can share a bit of the process and observation.

Near where I live I can easily find Oakmoss (Evernia prunastri) and the Yellow Wall Lichen (Xanthoria parietina).

I collected small samples of each and placed very small pieces of them into many agar dishes. The idea here is that, coming from a wild source, contaminants will be present for sure. The process of isolation is an iterative process in which you observe the growth on the plate, pick out a small region where your target organism is growing strongly, and then move it into another plate.

This is an agar plate into which pieces of Evernia were added:

In this image you can see that there is a wedge with fluffy white mycelium, which was consistent with the morphology for the mycelium of this species as described in the literature. So, I would pick a tiny piece from this region and transfer into a new plate, to obtain a clean mycelium after 1 or 2 transfers:

This process was also performed for Xanthoria parietina.

After this step, I had plates with "clean" mycelium but not yet confirmation that the mycelium was truly the lichen's mycobiont. That is when microscopic identification comes into play. I was especially happy with the microscopic images I was able to get of the Xanthoria because they clearly show structures that are very characteristic structure of "septate, pluricellular, branched hyphae" described in the literature.

At this point I now had the fungal component isolated in agar plates. This was for me the easy part because I am familiar with growing mushrooms. But to build a lichen we need two parts: a fungus and an algae.

From a search I could find that both lichen species may use algae of the genus Trebouxia as a symbiont. I placed small pieces of each lichen into water and made the following observations:

• When placed in water, some of the algal cells become dislodged and float away

Photo: Algal cells floating away from a piece of Evernia prunastri

• The algal cells can be seen held loosely in between the hyphae, rather than incorporated into the hyphal structure

Photo: Algal cells loosely bound to the hyphae of Evernia prunastri

Photo: Cluster of algal cells bound to the surface of a hypha of Xanthoria parietina

• Both species contained algar with similar if not identical round morphologies

Photo: Individual algal cell released from Xanthoria parietina

• The round morphology is consistent with Trebouxia

.... So, at this point I had successfully isolated the fungal partner and had some evidence to suggest that the binding between the fungus and the algae is loose. Since I saw that the algae could be released from a lichen, an easy thing try was to attempt to transfer the algae from a living lichen to the mycelium culture.

This is a photo of that attempt. Small pieces of wild Evernia were placed on top of a mycelium culture that was already several weeks old.

This... Did not work at all. The culture eventually became contaminated and was thrown away.

The next attempt was to try to grow the algae separately. One method was to place the wild lichen into agar dishes with no added nutrients end expose the dishes to the sun. The logic here is that the algae will survive from photosynthesis while the rest of the species do not have the nutrients to thrive on. I tried this on about 15 plates, different light conditions, but nothing grew other than a few weakly growing contaminants in some of the dishes...

Another method was to place the lichen into a glass jars filled with water and place those by the window at different levels of shade.

In the meantime, I decided to grow "grain spawn" jars out of the mycobiont thinking that this would give me a lot of material to work with once the algae grew. Both fungi did colonize the grain well. However, those jars were abandoned and eventually, after several months of storage, became contaminated and I had to toss them away.

It has been almost two years and I just had a look now at how the algae in jars are doing.

In the Xanthoria jar I can see significant algal growth. As for the Evernia, the algae did not make it but it looks like the mycelium did, as it has created a floating white blob.

A few months after having the algae jar sitting by the window I analyzed the mixture under the microscope and did observe a large amount of Trebouxia.

Right now I have checked another sample, and, while I do see what looks like a bit of Trebouxia (marked with a red arrow), unfortunately most of the mixture now consists of other unidentified algal species. Since Trebouxia is not the dominant species, it would probably be easier to re-isolate the algae from the wild instead of trying to isolate it from this mixture.

I will give it a second try, and this time I will place more emphasis on culturing the algae first and keeping the cultures healthy and pure.

The SCD4x sensor from Sensirion measures CO₂, temperature, and humidity, and communicates these values via I²C.

The measurement principle for the CO2 is that of photoacoustic sensing. The fundamental principle is shown in the diagram below: shine light that the CO2 molecules absorb and use a microphone to listen to the pressure variations.

I ordered a batch of SCD41 sensors from China for various projects, including fermentation, mushroom and plant cultivation, and field monitoring.

Since I had extras, I sacrificed one for macro photography. I removed the cover with a dremel and pliers, then cleaned the internals using isopropanol.

Here is my take:

The temperature and humidity are measured by Sensirion’s SHT40, seen as the black square at the bottom right. It’s likely accessed by the internal microcontroller over an internal I²C bus.

The pink square at the top left is a MEMS IR emitter. The SCD4x datasheet doesn’t specify the emission wavelength, but 4.3 µm is standard for NDIR-based CO₂ detection. A similar emitter example is this one from Microhybrid. These emitters usually produce broadband IR, with a 4.3 µm band-pass interference filter on top. The pink hue likely comes from this filter. Filters like these are critical to target CO₂ absorption while avoiding spectral overlap with other gases. For further reading, see Infratec's application note and Delta Optical Thin Film’s technical explanation.

The gold component labeled “o119 ANC” is the MEMS microphone, used to detect pressure waves caused by gas molecules absorbing pulsed IR light—this is photoacoustic sensing. The vibration excited by 4.3 µm light occurs at ~70 THz, far beyond acoustic detection. However, the IR source is pulsed at a modulation frequency (typically 20–60 Hz, e.g. 40 Hz), and the microphone detects the resulting pressure variations at this frequency. The principle is outlined in patent US 2024/0133801 A1.

An example of a compatible MEMS microphone is Infineon’s IM72D128V01, which supports frequencies down to 20 Hz.

The final main component is the metal-shielded package. It likely contains a microcontroller responsible for:

• Driving the MEMS IR emitter with a modulated current (e.g., at 40 Hz)
• Capturing and analyzing the MEMS microphone signal to extract the amplitude of acoustic pressure oscillations (proportional to CO₂ concentration)
• Acting as an I²C master to retrieve temperature and humidity data from the SHT40
• Acting as an I²C slave to provide CO₂, temperature, and humidity data to an external controller

Here are top and bottom views of the sensor cap:

The cap has a circular gas inlet. The white material covering it is likely a hydrophobic ePTFE membrane, which allows gas exchange while blocking liquid water.

I hope someone else finds this interesting too!

EDIT: After posted this, I searched online and I found a photo from someone who went a deeper than me and did expose the microcontroller: https://www.hackteria.org/wiki/CO2_Soil_Respiration_Chamber

This is the photo borrowed from that site:

There are a few people out there self-dosing with snake venom. The posted article is based on a study on the blood of one of these guys, Tim Friede, who has developed very effective antivenom in his blood after 20 years of self-dosing with a diverse array of snake venoms.

Vice did a few documentaries on Steve Ludwin, who is also self-immunizing. In one of these he answers questions about how he began and his motivation for doing what he does. In addition to producing anti-bodies he also believes that snake venoms have medicinal and anti-ageing properties - but these beliefs do not appear to be supported by any animal-based data as far as I can tell: https://www.youtube.com/watch?v=AcbqB0pFRPA

Self-dosing with snake venom is not something I would recommend. Generally a bad idea. But it is interesting to see the results and to learn about what motivates someone to do something like this.

Abstract

For nearly 450 million years, mycorrhizal fungi have constructed networks to collect and trade nutrient resources with plant roots1,2. Owing to their dependence on host-derived carbon, these fungi face conflicting trade-offs in building networks that balance construction costs against geographical coverage and long-distance resource transport to and from roots3. How they navigate these design challenges is unclear4. Here, to monitor the construction of living trade networks, we built a custom-designed robot for high-throughput time-lapse imaging that could track over 500,000 fungal nodes simultaneously. We then measured around 100,000 cytoplasmic flow trajectories inside the networks. We found that mycorrhizal fungi build networks as self-regulating travelling waves—pulses of growing tips pull an expanding wave of nutrient-absorbing mycelium, the density of which is self-regulated by fusion. This design offers a solution to conflicting trade demands because relatively small carbon investments fuel fungal range expansions beyond nutrient-depletion zones, fostering exploration for plant partners and nutrients. Over time, networks maintained highly constant transport efficiencies back to roots, while simultaneously adding loops that shorten paths to potential new trade partners. Fungi further enhance transport flux by both widening hyphal tubes and driving faster flows along ‘trunk routes’ of the network5. Our findings provide evidence that symbiotic fungi control network-level structure and flows to meet trade demands, and illuminate the design principles of a symbiotic supply-chain network shaped by millions of years of natural selection.

Abstract

Bolitoglossa digitigrada Wake, Brame and Thomas, 1982 was described from a few kilometers upstream from the Rio Santa Rosa, Ayacucho Region, Peru, at 1000 m a.s.l. in the Eastern Amazonian Montane Forest. Besides the type specimens, no additional collections or sightings of B. digitigrada had been reported for 43 years, and there is no information about its phylogenetic position inside its group. During a field expedition conducted in October 2022, we found four individuals of B. digitigrada in a corn and banana field near the community of San Jose, approximately 2.7 km from the type locality. Here, we provide information about living specimens, update description of coloration in life, elevation, and evaluate the phylogenetic relationships of B. digitigrada with a molecular phylogeny based on a 16S rRNA sequence.

Abstract

While observational studies and small pilot trials suggest that vitamin D, omega-3 and exercise may slow biological aging, larger clinical trials testing these treatments individually or in combination are lacking. Here, we report the results of a post hoc analysis among 777 participants of the DO-HEALTH trial on the effect of vitamin D (2,000 IU per day) and/or omega-3 (1 g per day) and/or a home exercise program on four next-generation DNA methylation (DNAm) measures of biological aging (PhenoAge, GrimAge, GrimAge2 and DunedinPACE) over 3 years. Omega-3 alone slowed the DNAm clocks PhenoAge, GrimAge2 and DunedinPACE, and all three treatments had additive benefits on PhenoAge. Overall, from baseline to year 3, standardized effects ranged from 0.16 to 0.32 units (2.9–3.8 months). In summary, our trial indicates a small protective effect of omega-3 treatment on slowing biological aging over 3 years across several clocks, with an additive protective effect of omega-3, vitamin D and exercise based on PhenoAge.